subtopic 2.1: Individuals, populations, communities, and ecosystems
Subtopic 2.1 introduces the fundamental concepts of ecology, focusing on the interconnectedness of individuals, populations, communities, and ecosystems. This comprehensive overview includes discussions on ecological niches, which describe the specific roles or functions that organisms play within their ecosystems, including how they utilize resources and interact with other species. It also covers key aspects of population biology, such as population dynamics, structure, and interactions within ecosystems, which are crucial for understanding how species populations evolve and sustain over time.
Additionally, the topic delves into the concept of carrying capacity—the maximum number of individuals of a particular species that an environment can support indefinitely, given the availability of essential resources like food, water, and habitat. Keystone species, which are critical to the stability and health of their ecosystems, are also explored; their presence or absence can have significant cascading effects on other species and the ecosystem's overall functionality. Furthermore, this section addresses the broader ecological frameworks of biosphere integrity and planetary boundaries, which help in understanding the limits within which human activities and natural processes can coexist sustainably. These frameworks are vital for recognizing the ecological thresholds that should not be crossed to maintain a stable planet. This foundational knowledge in ecology is pivotal for students as it lays the groundwork for more advanced studies in environmental systems and their complex interactions.
Additionally, the topic delves into the concept of carrying capacity—the maximum number of individuals of a particular species that an environment can support indefinitely, given the availability of essential resources like food, water, and habitat. Keystone species, which are critical to the stability and health of their ecosystems, are also explored; their presence or absence can have significant cascading effects on other species and the ecosystem's overall functionality. Furthermore, this section addresses the broader ecological frameworks of biosphere integrity and planetary boundaries, which help in understanding the limits within which human activities and natural processes can coexist sustainably. These frameworks are vital for recognizing the ecological thresholds that should not be crossed to maintain a stable planet. This foundational knowledge in ecology is pivotal for students as it lays the groundwork for more advanced studies in environmental systems and their complex interactions.
SL/HL
This unit will take a minimum of 6 hours.
Guided Questions
- How can natural systems be modelled, and can these models be used to predict the effects of human disturbance?
- How do population dynamics such as birth rates and death rates influence the stability of an ecosystem?
Understandings
ecosystems foundation
2.1.1 The biosphere is an ecological system composed of individuals, populations, communities, ecosystems.
- Define 'biosphere'
- Draw a simple diagram of the biosphere illustrating its components: individuals, populations, communities, and ecosystems.
https://civilaspirant.in/levels-of-organisation-in-ecology/
The biosphere is the global ecological system integrating all living beings and their relationships, including their interactions with the elements of the lithosphere (earth), hydrosphere (water), and atmosphere (air). This concept underscores the interconnected nature of life on Earth, highlighting the biosphere as the sum of all ecosystems.
Key Elements of the Biosphere:
Key Elements of the Biosphere:
- Ecosystems: Ecosystems comprise communities and their non-living environments functioning as a single unit. The health of ecosystems is often gauged by their biodiversity, productivity, and the cyclic movements of energy and nutrients.
- Communities: A community is a group of populations of different species that live in the same area and interact with each other. These interactions can include various forms of symbiosis, competition, and predation.
- Populations: A population is a group of individuals of the same species living in a specific area, capable of interbreeding. Population dynamics, such as growth rates and migration, play a crucial role in the health and evolution of ecosystems.
- Individuals: The smallest unit in the ecological hierarchy, an individual is a single organism capable of independent survival.
The Significance of the Biosphere:
- The biosphere includes all of Earth's life-supporting zones, providing essential resources like air, water, and soil. Understanding its structure—from individuals to ecosystems—is vital for conservation, resource management, and climate action.
2.1.2 An individual organism is a member of a species.
- Define species with reference to a named example
- Outline the problems associated with the species model
That definition of a species might seem cut and dried, but it is not — in nature, there are lots of places where it is difficult to apply this definition. For example, many bacteria reproduce mainly asexually. The bacterium shown at right is reproducing asexually, by binary fission.
A species is a group of organisms that can interbreed and produce fertile offspring. A species is often defined as a group of individuals that actually or potentially interbreed in nature. In this sense, a species is the biggest gene pool possible under natural conditions.
A species is a group of organisms that can interbreed and produce fertile offspring. A species is often defined as a group of individuals that actually or potentially interbreed in nature. In this sense, a species is the biggest gene pool possible under natural conditions.
https://www.treehugger.com/bengal-tiger-facts-5074560
Example: Bengal Tiger
Raja is an individual Bengal Tiger living in the Sundarbans mangrove forest in India. As a member of the species Panthera tigris tigris, Raja shares several characteristics with other Bengal Tigers, including physical traits, behaviors, and genetic makeup.
- Name: Raja
- Species: Bengal Tiger (Panthera tigris tigris)
Raja is an individual Bengal Tiger living in the Sundarbans mangrove forest in India. As a member of the species Panthera tigris tigris, Raja shares several characteristics with other Bengal Tigers, including physical traits, behaviors, and genetic makeup.
The Species Model
The species model is a conservation approach that focuses on protecting individual species, particularly those that are endangered, charismatic, or economically important. The model prioritizes the survival and management of specific species, often through targeted efforts like habitat protection, breeding programs, or legal protections.
While this model can successfully save certain species, it has limitations
The species model is a conservation approach that focuses on protecting individual species, particularly those that are endangered, charismatic, or economically important. The model prioritizes the survival and management of specific species, often through targeted efforts like habitat protection, breeding programs, or legal protections.
While this model can successfully save certain species, it has limitations
2.1.3 Classification of organisms allows for efficient identification and prediction of characteristics.
- Define taxonomy
- Explain why it is important to italicize or underline the genus and species names in scientific nomenclature
https://uspeakgreek.com/science/biology/taxonomy-tracing-its-greek-roots-to-modern-biological-classification/
- Taxonomy: The classification system for organizing Earth's diverse life forms.
- Linnaean System: Developed by Charles Linnaeus, this system helps identify organisms and predict characteristics, aiding in the study of biological relationships and evolution.
- Binomial Name: Each species has a two-part scientific name—genus (group with similar traits) and species name, written in Latin, italicized or underlined.
- Ecological Importance: Knowing local species helps understand their role in ecosystems and the need to protect them.
Key Elements of Classification:
- Hierarchical Structure: Organisms are classified into a hierarchy that includes several levels such as kingdom, phylum, class, order, family, genus, and species. This structure helps in understanding the evolutionary relationships among different organisms.
- Binomial Nomenclature: Each species is given a unique two-part name. This system, developed by Carl Linnaeus, uses the genus name and the species name to form the full scientific name of an organism. For example, the house cat is officially named Felis catus.
Organizing organisms into a taxonomic system presents challenges. Nature doesn't always conform to the categories we define; many species exhibit characteristics that span multiple groups. Moreover, ongoing discoveries in microscopic details and genetic traits frequently compel revisions to established taxonomic classifications, underscoring the complexity and fluidity of categorizing biological diversity
https://www.snexplores.org/article/biology-species-name-linnaeus-taxonomy
2.1.4 Taxonomists use a variety of tools to identify an organism.
- Explain how to identify organisms using keys, technology and scientific expertise
Tools for Species Identification:
- Taxonomists use tools like dichotomous keys and DNA analysis to distinguish species. Specimen samples in museums and labs also aid in identification.
- A practical tool used to identify organisms by their physical traits through a series of questions or statements.
- Series of Choices: Each step presents two choices about specific features (e.g., leaf shape, body size).
- Sequential Process: Users follow a path based on observed traits until the organism is identified.
- Final Identification: Each decision narrows the options, leading to the organism's name.
- Used in education, research, and fieldwork, dichotomous keys help users make precise identifications, promoting observation and critical thinking.
Here are some good databases to explore taxonomy
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| Salamander Dichotomous Key Activity.docx |
Population and Community Dynamics
2.1.5 A population is a group of organisms of the same species living in the same area at the same time, and which are capable of interbreeding.
- Define population with reference to a named example
- State the factors that affect a population
image from www.ieu.uzh.ch
- A population includes all individuals of a single species in a specific area at a given time, capable of interbreeding.
- Key Characteristics:
- Interbreeding: Populations are defined by the genetic exchange among members, essential for adaptation and survival.
- Boundaries: Populations have flexible spatial and temporal boundaries that can shift with environmental changes or migration.
- Multiple Populations per Species: A species may have multiple distinct populations due to geographic or behavioral barriers, leading to varied evolutionary paths.
- Ecological Role of Populations:
- Fundamental Unit: Populations are essential for studying ecological interactions, like competition and symbiosis.
- Dynamics: Birth, death, immigration, and emigration rates inform predictions on population size and ecosystem health.
- Importance of Population Studies:
- Conservation: Focuses on preserving endangered populations and genetic diversity.
- Resource Management: Ensures sustainable use of resources to prevent population imbalances in ecosystems.
APPLICATION OF SKILLS: Investigate a local ecosystem.
- Investigate the populations of a common urban bird species, such as pigeons or sparrows, within a city park.
- Examine a population of a specific tree species within a local forest or woodland area.
- Analyze the population dynamics of a fish species in a local stream or river ecosystem.
- Study the population of a particular insect species within an agricultural setting, such as bees in an orchard.
- Investigate populations of a marine species like mussels or barnacles along a coastal rocky shore.
2.1.6 Factors that determine the distribution of a population can be abiotic or biotic.
- Define biotic and abiotic
In ecology, the distribution of populations within an ecosystem is influenced by a complex interplay of both biotic and abiotic factors. Understanding these factors is essential for comprehending how populations adapt, survive, and interact within their environments
- Biotic: All the plants, animals, algae, fungi and microbes in an ecosystem.
- Abiotic: The chemical and physical factors in an ecosystem (non living) for example: temperature, moisture, salinity, soil type, light, air
Biotic Factors:
Biotic factors can be grouped by their general role in an ecosystem:
Abiotic Factors
Abiotic factors vary in the environment and determining the types and numbers of organisms that exist in that environment. These factors are critical as they often set hard limits on where organisms can survive. Key abiotic factors include:
- Competition: Organisms compete for limited resources like food, water, and space. For example, two tree species may compete for sunlight, influencing their growth and spatial distribution within a forest.
- Predation: Predator-prey relationships significantly influence the distribution of species. Areas with high predator concentrations may see lower populations of certain prey species.
- Symbiosis: Interactions like mutualism, where two species benefit from their relationship, can enhance the ability of populations to expand into new areas or thrive in existing ones. An example is the relationship between bees and flowering plants, where bees pollinate flowers while feeding on their nectar.
- Disease: Pathogens can control the population size and distribution by reducing the number of susceptible individuals in a population.
Biotic factors can be grouped by their general role in an ecosystem:
- producers: plants that produce their own food
- consumers: animals that eat plants and other animals
- decomposers: organisms that break down the waste of other organisms
Abiotic Factors
Abiotic factors vary in the environment and determining the types and numbers of organisms that exist in that environment. These factors are critical as they often set hard limits on where organisms can survive. Key abiotic factors include:
- Temperature: The range of temperature in a region can determine which organisms are capable of surviving there based on their physiological thermal limits.
- Water: Moisture availability affects where organisms can live, particularly plants and aquatic organisms. Different species require different amounts of water, influencing their geographical distribution.
- Soil Type: The composition and characteristics of soil, including its texture, pH, and nutrient content, influence the types of plants that can grow, which in turn affects the distribution of various animal populations dependent on those plants.
- Light: The amount and intensity of light can influence where plant species grow, as photosynthesis is light-dependent. This, in turn, affects the distribution of animal species that rely on those plants for food or habitat.
- Altitude and Geography: Higher altitudes may have cooler temperatures and less oxygen, which can limit which species are able to thrive. Geographic barriers like mountains or rivers can also restrict the movement of species, influencing their distribution patterns.
2.1.7 Temperature, sunlight, pH, salinity, dissolved oxygen and soil texture are examples of many abiotic factors that affect species distributions in ecosystems.
- Define limiting factor
- Explain how salinity and temperature variations can affect the distribution of marine species.
- Describe the role of soil texture in determining the types of vegetation that can thrive in a terrestrial ecosystem
Factors which determine the types and numbers of organisms of a species in an ecosystem are called limiting factors. Many limiting factors restrict the growth of populations in nature. An example of this would include low annual average temperature average common to the Arctic restricts the growth of trees, as the subsoil is permanently frozen.
Understanding these abiotic factors, helps us appreciate the complex interactions within ecosystems and the adaptive strategies employed by organisms to cope with environmental stresses
Understanding these abiotic factors, helps us appreciate the complex interactions within ecosystems and the adaptive strategies employed by organisms to cope with environmental stresses
- Temperature
- Impact: Temperature significantly affects the metabolic rates of organisms. It influences growth rates, reproduction, and survival rates, shaping the geographic distribution of species.
- Example: Tropical ecosystems are characterized by high biodiversity partly due to warm temperatures, which accelerate metabolic processes and lead to higher productivity and faster decomposition.
- Light
- Impact: Light is crucial for photosynthesis in plants and influences the behavior and reproductive cycles of various organisms. Light availability can affect plant growth and, by extension, the animals that depend on those plants for food and habitat.
- Example: In forest ecosystems, canopy layers significantly affect light penetration, creating distinct microenvironments. Understory plants have adapted to low light conditions, often growing larger leaves to capture more sunlight.
- Water
- Impact: Water availability is a critical determinant of species distribution and ecosystem productivity. It affects plant water stress and the water balance of all organisms in an ecosystem.
- Example: Desert plants such as cacti have adaptations like thick cuticles and reduced leaf surfaces to minimize water loss, allowing them to thrive in arid environments with limited water availability.
- Wind
- Impact: Wind can influence the temperature and moisture level of environments. It affects the rate of transpiration in plants, seed and pollen dispersal, and can physically shape the structure of plants and the landscape.
- Example: In coastal ecosystems, strong winds can lead to the development of salt-tolerant plant species with structural adaptations like thick stems and waxy leaves to reduce water loss.
- Soil
- Impact: Soil properties, including texture, composition, pH, and nutrient content, are vital for plant growth. These properties determine not only which plants can thrive in an area but also the types of animals that can be supported.
- Example: In tropical rainforests, rapid decomposition and nutrient uptake result in nutrient-poor soils. The lush vegetation primarily relies on the rapid recycling of nutrients from decomposing organic material.
- pH
- Impact: The pH level of soil and water can influence nutrient availability and toxicity, thereby affecting plant health and the types of microbial communities that can exist in an environment.
- Example: In freshwater ecosystems, a lower pH (more acidic water) can result from industrial pollution (acid rain), affecting aquatic life by altering ion balance and increasing metal solubility, which can be toxic.
- Soil Texture
- Impact: Soil texture, determined by the size of soil particles, affects water retention and air circulation within the soil. This influences root growth and nutrient uptake by plants.
- Example: Sandy soils, with large particle sizes, drain quickly and do not hold nutrients well, affecting the types of vegetation that can thrive. Plants in these soils often have deep root systems to access lower moisture reserves.
- Dissolved Oxygen
- Impact: Dissolved oxygen in water is crucial for aquatic life. It affects respiration in aquatic organisms and plays a role in determining water quality.
- Example: Low levels of dissolved oxygen in water bodies can lead to hypoxic conditions, making it difficult for fish and other aquatic species to survive. This often occurs due to excessive nutrient pollution from agricultural runoff, leading to algal blooms that deplete oxygen.
APPLICATION OF SKILLS: Use methods for measuring at least three abiotic factors in an aquatic or terrestrial ecosystem, including the use of data logging.
- Analyze temperature, pH, and dissolved oxygen levels in a freshwater pond.
- Measure salinity and temperature gradients in a coastal salt marsh ecosystem.
- Investigate sunlight exposure and soil texture in a forest ecosystem.
- Examine temperature, sunlight, and soil pH in a mountainous terrain.
- Measure temperature, light, and soil texture in various sections of an urban park.
- Investigate temperature, sunlight, and soil texture in a desert ecosystem.
- Monitor UV radiation, temperature, and oxygen levels in a high-altitude ecosystem.
- Analyze temperature and light pollution in different urban and suburban areas.
2.1.8 A niche describes the particular set of abiotic and biotic conditions and resources upon which an organism or a population depends.
- Define niche with reference to a named example
- Distinguish between biotic and abiotic (physical) components of an ecosystem
image from www.paulnoll.com
An ecological niche includes all biotic and abiotic conditions a species requires to survive, grow, and reproduce, along with its functional role in the ecosystem.
Key Aspects of a Niche:
Niche Differentiation and Competition:
Importance of Niche Concepts:
Key Aspects of a Niche:
- Resource Use: The specific resources needed, like food and shelter, shape each species’ niche. Example: Different rainforest plants have unique light, nutrient, and water requirements.
- Functional Role: A species' role (e.g., predator, decomposer, pollinator) affects interactions within the ecosystem and contributes to energy flow and nutrient cycling.
- Environmental Tolerances: Species-specific tolerances (temperature, pH, etc.) define where a species can thrive.
Niche Differentiation and Competition:
- Niche Differentiation: Species can share habitats by using different resources (e.g., squirrels and rabbits coexist by eating different foods).
- Niche Overlap: When two species rely on the same resources, competition occurs, potentially leading to exclusion or niche adaptation for coexistence.
Importance of Niche Concepts:
- Conservation: Understanding niches aids in habitat management and species survival.
- Response to Change: Helps predict how species may react to environmental shifts, such as climate change or habitat loss.
The North American Beaver (Castor canadensis) and Its Ecological Niche
The North American beaver is a keystone species in aquatic and riparian ecosystems, illustrating a complex ecological niche.
Habitat Modification:
Water Regulation:
Temperature and Water Quality Control:
Habitat for Other Species:
Nutrient Cycling:
Biodiversity Enhancement:
Moisture Retention
The North American beaver is a keystone species in aquatic and riparian ecosystems, illustrating a complex ecological niche.
Habitat Modification:
- Beavers are well-known for their ability to drastically alter landscapes through the construction of dams and lodges using tree trunks, branches, and mud. These activities create wetlands, which are crucial for biodiversity, providing habitat for many species including fish, birds, and amphibians.
Water Regulation:
- By building dams, beavers help to maintain water levels within watercourses, which can reduce the severity of droughts and mitigate flood damage downstream. The ponds created by beaver dams increase sediment retention, which enhances the aquifer recharge in dry periods.
Temperature and Water Quality Control:
- The wetlands and ponds created and maintained by beavers can help to regulate water temperature by providing shaded areas and reducing water velocity. These factors are critical for sustaining fish populations, particularly salmon and trout, which require specific temperature ranges. Additionally, these water bodies help in filtering out pollutants, improving overall water quality.
Habitat for Other Species:
- Beaver ponds increase the structural diversity of habitats in their vicinity. These areas often support a higher diversity of bird species and provide critical breeding habitat for amphibians such as frogs and newts. Migratory bird species frequently utilize beaver wetlands as resting and feeding sites.
Nutrient Cycling:
- Beavers contribute to nutrient cycling within their ecosystems. The material they use to build dams and the organic matter that accumulates in beaver ponds decomposes, releasing nutrients back into the ecosystem and enhancing soil fertility around the water bodies.
Biodiversity Enhancement:
- The diverse habitats created by beavers support a wide array of species. The changes in landscape and hydrology driven by beaver activity can lead to increased biodiversity within the ecosystem, showcasing the broad ecological impact beavers have beyond just their immediate surroundings.
Moisture Retention
- Beaver ponds increase the moisture content of the surrounding area through water seepage and increased humidity from the standing water. This added moisture can make the surrounding vegetation less susceptible to ignition during dry conditions. Wetlands created by beavers act as natural firebreaks, slowing the spread of fires.
2.1.9 Populations interact in ecosystems by herbivory, predation, parasitism, mutualism, disease and competition, with ecological, behavioural and evolutionary consequences.
- Define population dynamics
- Distinguish between intraspecific competition and interspecific competition
- Describe competitive exclusion
- Define predation, herbivory, parasitism, mutualism, disease and competition with reference to named examples
- Distinguish a predator from a parasite
- Explain why competition for a resource has negative effects
The word symbiosis literally means 'living together,' but when we use the word symbiosis in biology, what we're really talking about is a close, long-term interaction between two different species. There are many different types of symbiotic relationships that occur in nature.
https://www.ck12.org/c/biology/competition/lesson/Competition-BIO/
Competition is where organisms compete for a resource that is in limited supply (water, food, territory, mates, habitat, etc.).
There are two different classifications of competition
There are two different classifications of competition
- Intraspecific competition: competition between members of the same species. For example two oak trees growing too close together fighting for sunlight and nutrients or two male deer competing for mates.
- Interspecific competition: . Individuals of the different species, competing for the same resources. Competition is where organisms compete for a resource that is in limited supply (water, food, territory, mates, habitat, etc.).
- The other outcome is that one species may totally out compete the other, this is the principle of Competitive exclusion.
https://www.bigbluebug.com/blog/post/professional-mosquito-and-tick-control-say-goodbye-to-outdoor-parasites-in-your-massachusetts-yard
parasitism - The host provides a habitat and food for the bacteria, but in return, the bacteria cause disease in the host. This is an example of parasitism or an association between two different species where the symbiont benefits and the host is harmed. Not all parasites have to cause disease.
Parasites of animals are highly specialized, and reproduce at a faster rate than their hosts. Classic examples include interactions between vertebrate hosts and tapeworms, flukes, the malaria-causing Plasmodium species, and fleas.
Parasites of animals are highly specialized, and reproduce at a faster rate than their hosts. Classic examples include interactions between vertebrate hosts and tapeworms, flukes, the malaria-causing Plasmodium species, and fleas.
https://www.researchgate.net/figure/Partner-sanctions-by-mutualistic-ants-Adapted-mutualist-ants-Pseudomyrmex-ferrugineus_fig1_256459064
mutualism - benefit both interacting species. Examples include pollinators that feed on nectar while helping plants reproduce, and mycorrhizal fungi that enhance nutrient absorption for plants in exchange for carbohydrates. These interactions often lead to highly specialized adaptations and interdependencies.
Certain species of Acacia trees have evolved a mutualistic relationship with ant colonies, particularly in Africa and Central America. These trees are often referred to as "ant-acacias."
The presence of ants reduces damage to the Acacia from herbivores and competing plants, allowing the tree to grow more vigorously and reproduce more successfully.
This mutualism not only benefits the ants and the Acacia but also influences the broader ecological community. For example, the area cleared by ants around the tree can become a microhabitat for other species, and the well-maintained Acacia can provide food and habitat for various insects and birds.
This mutualistic relationship illustrates coevolution, where two species evolve in response to each other's influence. The Acacia's adaptations to produce nectaries and housing structures are likely responses to the protective services of the ants, while the ants have adapted to rely on these specific trees for food and shelter.
Certain species of Acacia trees have evolved a mutualistic relationship with ant colonies, particularly in Africa and Central America. These trees are often referred to as "ant-acacias."
- Ant Benefits: The Acacia provides the ants with food and shelter. The trees produce specialized structures called nectaries that secrete a sugary solution, which the ants consume. Additionally, the Acacia trees have swollen thorns that the ants use as protective nesting sites.
- Acacia Benefits: In return, the ants protect the tree from herbivores and invasive plant species. The ants aggressively defend the tree against browsing animals by swarming and biting them. They also prune away other plants that might compete with the Acacia for sunlight and nutrients, effectively clearing the area around the tree.
The presence of ants reduces damage to the Acacia from herbivores and competing plants, allowing the tree to grow more vigorously and reproduce more successfully.
This mutualism not only benefits the ants and the Acacia but also influences the broader ecological community. For example, the area cleared by ants around the tree can become a microhabitat for other species, and the well-maintained Acacia can provide food and habitat for various insects and birds.
This mutualistic relationship illustrates coevolution, where two species evolve in response to each other's influence. The Acacia's adaptations to produce nectaries and housing structures are likely responses to the protective services of the ants, while the ants have adapted to rely on these specific trees for food and shelter.
https://mdc.mo.gov/wildlife/wildlife-diseases
disease - pathogens can drastically alter the structure of populations and communities. Diseases can quickly reduce population size, affect genetic diversity, and trigger behavioral changes in affected species. The presence of disease can also influence the competitive dynamics among species in an ecosystem.
Canine and feline distemper are caused by two different viruses that affect wild and domestic carnivores.
Canine and feline distemper are caused by two different viruses that affect wild and domestic carnivores.
herbivory - this interaction occurs when herbivores consume plant material. It affects plant population dynamics and can lead to evolutionary adaptations in plants such as the development of thorns, toxic chemicals, or other defensive mechanisms. Herbivory also influences the spatial distribution and reproductive strategies of plant populations.
When deer populations are high, their intense browsing pressure can prevent the regeneration of certain tree species by eating the saplings before they mature. This selective feeding can lead to changes in forest composition, favoring species that are less palatable to deer.
Persistent herbivory pressure can lead to evolutionary changes in plants. Some species may develop traits that reduce their palatability to deer, such as tougher leaves, increased production of defensive chemicals, or changes in growth patterns that make them less accessible.
Plants may exhibit a range of responses to reduce the impact of deer herbivory, including altering their reproductive timing or growing in locations that are less accessible to deer.
When deer populations are high, their intense browsing pressure can prevent the regeneration of certain tree species by eating the saplings before they mature. This selective feeding can lead to changes in forest composition, favoring species that are less palatable to deer.
Persistent herbivory pressure can lead to evolutionary changes in plants. Some species may develop traits that reduce their palatability to deer, such as tougher leaves, increased production of defensive chemicals, or changes in growth patterns that make them less accessible.
Plants may exhibit a range of responses to reduce the impact of deer herbivory, including altering their reproductive timing or growing in locations that are less accessible to deer.
https://speciesconnect.com/predation/carnivory/predation-carnivore-examples/
predation - one organism (the predator) feeds on another organism (the prey). This interaction is a critical driving force for natural selection, promoting adaptations like camouflage in prey and enhanced sensory abilities in predators. Predation regulates population sizes, maintains species diversity, and can shape community structure.
The praying mantis is a carnivorous insect known for its predatory skills, which make it a formidable hunter within its ecosystem. Mantises are widely recognized by their distinctive posture of folded forearms, which gives the appearance of prayer. Praying mantises have developed excellent camouflage that mimics leaves, sticks, or flowers, enhancing their ability to ambush prey. Their slow, deliberate movements help them go unnoticed until they strike.
They can also turn their heads 180 degrees to scan their surroundings for prey and predators, a unique ability among insects
Praying mantises help control the populations of the insects they consume, which can include a wide range of species from flies to moths, and even other mantises. This predatory activity helps balance insect populations, preventing any single species from becoming overly dominant, which could lead to detrimental effects on the ecosystem.
The praying mantis is a carnivorous insect known for its predatory skills, which make it a formidable hunter within its ecosystem. Mantises are widely recognized by their distinctive posture of folded forearms, which gives the appearance of prayer. Praying mantises have developed excellent camouflage that mimics leaves, sticks, or flowers, enhancing their ability to ambush prey. Their slow, deliberate movements help them go unnoticed until they strike.
They can also turn their heads 180 degrees to scan their surroundings for prey and predators, a unique ability among insects
Praying mantises help control the populations of the insects they consume, which can include a wide range of species from flies to moths, and even other mantises. This predatory activity helps balance insect populations, preventing any single species from becoming overly dominant, which could lead to detrimental effects on the ecosystem.
Ecological, Behavioral, and Evolutionary Consequences:
- Ecological: These interactions determine the distribution and abundance of species, structure food webs, and drive the dynamics of energy and nutrient cycles within ecosystems.
- Behavioral: Interactions like predation and parasitism can lead to the evolution of complex behaviors such as group living, which may provide safety in numbers, or nocturnality in prey species to avoid diurnal predators.
- Evolutionary: Over time, interactions among populations can lead to coevolution, where two or more species reciprocally influence each other’s evolution. An example is the evolution of flowering plants and their specific pollinators, which have developed matching morphologies to ensure successful pollination.
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Application of Skills: Use models that demonstrate feeding relationships, such as predator–prey.
For the application of ecological concepts involving models that demonstrate feeding relationships, particularly predator-prey dynamics, here are several hands-on and engaging activities that can be used in educational settings to enhance understanding and apply ecological skills:
- Interactive Predator-Prey Simulation: use software or web-based simulations where they manipulate variables such as initial population sizes, birth rates, death rates, and food availability.
- Role-Playing Game: Predator vs. Prey: Set up an outdoor game where some students are predators and others are prey. The prey have objectives (like collecting food tokens) while avoiding predators
| Predator/Prey Game.pdf |
https://www.researchgate.net/figure/Lotka-Volterra-Formal-Equations-Figure-3-Causal-Loop-Diagram-of-Predator-Prey_fig3_271837922
2.1.10 Carrying capacity is the maximum size of a population determined by competition for limited resources.
- Define carrying capacity
- Outline the role of predation in regulating the carrying capacity of a deer population in a forest ecosystem.
- List three abiotic factors that can influence the carrying capacity of a marine ecosystem.
- Describe how climate change could potentially alter the carrying capacity of the Arctic tundra for polar bears.
image from www.geo.arizona.edu
Carrying capacity is a fundamental concept in ecology that describes the maximum population size of a species that an environment can sustain indefinitely, given the food, habitat, water, and other necessities available in the environment. This capacity is not static; it varies over time as environmental conditions change, and as the availability of resources shifts due to various factors.
Key Aspects of Carrying Capacity:
Key Aspects of Carrying Capacity:
- Resource Limitation: Population growth is tied to resource availability. As resources dwindle, competition increases, stabilizing or reducing population size.
- Dynamic Nature: Carrying capacity fluctuates due to factors like environmental changes and resource availability.
- Food: Availability impacts how many individuals an ecosystem can support (e.g., droughts reduce food sources for birds).
- Water: Crucial for life, especially in arid environments and aquatic ecosystems, where water availability limits population sizes.
- Habitat Space: Physical space for living and reproducing limits populations (e.g., nesting sites for birds).
- Predation & Disease: Increased predators or disease outbreaks lower carrying capacity for prey species.
- Climate: Influences resource availability; extreme weather can reduce carrying capacity (e.g., caribou in Arctic tundra depend on winter food sources).
- Human Impact: Activities like deforestation and overfishing drastically lower ecosystem carrying capacities.
- Abiotic factors (e.g., pollution, deforestation) and climate changes from human actions reduce carrying capacity by altering ecosystems.
- Understanding carrying capacity aids in wildlife management, setting sustainable limits, and restoring habitats to support species populations.
2.1.11 Population size is regulated by density-dependent factors and negative feedback mechanisms.
- Define 'density-dependent factors' and 'density-independent factors'
- Describe how a density-independent event like a wildfire could affect the population size of a forest ecosystem.
- Compare and contrast the effects of a severe storm (a density-independent factor) and an outbreak of disease (a density-dependent factor) on a bird population
Population size in ecosystems is not limitless; it is regulated through a series of ecological checks and balances influenced by the density of the population. This regulation is crucial for maintaining ecosystem stability and preventing the overexploitation of resources.
Density-Dependent Factors:
Density-Dependent Factors:
- Competition for Resources: As populations grow, competition for food, water, and space increases, reducing growth rates through malnutrition, lower reproduction, and higher mortality.
- Increased Predation: Higher densities make species more visible to predators, helping balance prey populations with the ecosystem’s carrying capacity.
- Disease Transmission: High density accelerates the spread of disease, reducing population sizes, especially when individuals are weakened by resource competition.
- Natural Disasters: Events like wildfires and floods reduce population sizes regardless of density.
- Climatic Changes: Extreme weather (e.g., droughts, cold snaps) affects survival across all individuals.
- Combined Effects: Density-dependent factors regulate long-term population stability, while independent factors cause sudden changes.
- Predator-Prey Dynamics: Predator and prey populations influence each other in a feedback loop, maintaining ecological balance.
2.1.12 Population growth can either be exponential or limited by carrying capacity.
- Define 'exponential growth' and 'logistic growth' in the context of population dynamics.
- Describe and explain S and J population curves.
- Explain the factors that cause a population to shift from exponential to logistic growth.
- Describe how carrying capacity can influence the shape of a logistic growth curve in a population.
Population growth patterns are fundamental concepts in ecology, reflecting how populations expand under various environmental conditions and constraints. These growth patterns can be described primarily through two models: exponential growth and logistic growth, which consider the presence or absence of limiting factors.
Exponential Growth (J-Curve):
- Description: Occurs when a population grows rapidly without limitations, resulting in a J-shaped curve over time.
- Characteristics: Assumes unlimited resources, no competition, and ideal conditions, allowing all individuals to survive and reproduce, leading to rapid increases.
- Example: Algae and locusts often exhibit exponential growth during specific seasons, followed by sudden population crashes.
- decrease in population at the end of the season
https://ibguides.com/biology/notes/populations/
Logistic Growth (S-Curve):
- Description: Growth slows as the population nears carrying capacity, forming an S-shaped curve. It reflects a more realistic scenario where resources become limited.
- Characteristics: Density-dependent factors like competition, predation, and disease increase as the population grows, stabilizing the size near the carrying capacity.
- Example: Deer populations in regulated forests grow rapidly at first but stabilize as resources like space and food become limited.
https://www.differencebetween.com/difference-between-biotic-potential-and-carrying-capacity/
Boom and Bust Cycles:
Graphical Representation
- Description: Populations rapidly grow ("boom") and then sharply decline ("bust") after overshooting carrying capacity, often falling below initial levels.
- Characteristics: Cycles may repeat if resources recover, leading to rapid growth followed by another bust. Fluctuations are more extreme than in logistic growth.
- Example: The reindeer on St. Matthew Island boomed after introduction in 1944 but crashed in the 1960s due to overgrazing and starvation.
Graphical Representation
- Population Graphs: Understanding population growth through graphical representations helps in visualizing how populations respond to environmental conditions and resource limitations.
- Exponential Growth: Shown as a continuously rising curve.
- Logistic Growth: Starts similar to exponential but levels off as it approaches carrying capacity.
- Boom and Bust: Features sharp peaks and drastic falls, reflecting rapid growth followed by a collapse.
Reindeer of St. Matthew Island Case Study
https://medium.com/@awells/the-loneliest-place-in-alaska-1f7c71098027
https://medium.com/@awells/the-loneliest-place-in-alaska-1f7c71098027
Background
- In 1944, during World War II, the U.S. Coast Guard introduced 29 reindeer to St. Matthew Island as a part of a project to provide an emergency food source for stationed troops. Initially, the island seemed an ideal environment for the reindeer. It was isolated, had no natural predators, and was covered with abundant lichen—a favorite food of reindeer.
https://www.geo.arizona.edu/Antevs/nats104/00lect21reindeer.html
Population Growth
Population Crash
Lessons Learned
- Initial Boom: With plentiful food and no predators, the reindeer population experienced exponential growth. By 1963, the population had soared to an estimated 6,000 individuals.
- Resource Depletion: The rapid increase in population led to severe overgrazing. The reindeer consumed the lichen faster than it could regenerate, leading to a critical depletion of their primary food source.
Population Crash
- The Bust: The consequences of overpopulation became apparent in the harsh winter of 1963-1964. With their food sources drastically reduced, the reindeer were unable to sustain their large numbers. The population crashed to around 42 reindeer by 1966, and further declined to just a few by the early 1980s.
- Ecological Impact: The crash not only decimated the reindeer population but also left long-term ecological impacts on the island’s vegetation. The overgrazed lichen beds did not fully recover for decades, altering the island’s vegetation structure and impacting other species dependent on the same habitat.
Lessons Learned
- Carrying Capacity: This case vividly illustrates the concept of carrying capacity—the maximum population size that an environment can sustain indefinitely. Once the carrying capacity is exceeded, population decline is often rapid and severe.
- Sustainability: It serves as a cautionary tale about sustainable resource use and the dangers of introducing non-native species to isolated ecosystems without adequate consideration of ecological constraints and future consequences.
- Conservation and Management: For ecologists and conservationists, the story of St. Matthew Island is a critical case study in population dynamics and resource management. It emphasizes the need for careful planning and management when altering environments and introducing species to new habitats.
| Reindeer of St Matthew Data Activity.docx |
2.1.13 Limiting factors on the growth of human populations have increasingly been eliminated, resulting in consequences for sustainability of ecosystems.
- Define ecological footprint
- Explain how technological advancements in agriculture have influenced human population growth and ecosystem sustainability.
- Describe the environmental consequences of reducing natural predation on human population dynamics.
- Discuss the potential risks and consequences of human populations exceeding the Earth’s carrying capacity.
Key Ideas on Human Population Growth and Its Environmental Impact
Factors Contributing to Population Growth:
Environmental Consequences of Population Growth:
Global Sustainability Implications:
Future Considerations:
- Accelerated Growth: Human population growth has surged due to advancements in technology, medicine, and agriculture, removing many natural limiting factors.
Factors Contributing to Population Growth:
- Technological Advances:
- Health Improvements: Vaccines, antibiotics, and better sanitation have reduced mortality and increased life expectancy.
- Agricultural Innovations: High-yield crops, synthetic fertilizers, and pesticides from the Green Revolution boosted food production, supporting larger populations but straining ecosystems.
- Reduction of Natural Predation:
- Safety Enhancements: Advancements in weapons and secured settlements have eliminated natural predation threats, allowing for freer population expansion.
Environmental Consequences of Population Growth:
- Resource Depletion: Increased demand depletes resources like minerals, water, and energy faster than they can regenerate.
- Habitat Destruction: Urban expansion and agriculture lead to significant habitat loss, reducing biodiversity and altering ecosystems.
- Pollution: Industrial and agricultural pollutants overwhelm ecosystems, impacting wildlife and human health.
Global Sustainability Implications:
- Ecosystem Imbalance: Overpopulation stresses ecosystems, threatening essential services like climate regulation and water filtration.
- Carrying Capacity Concerns: Current population and consumption levels may exceed Earth’s sustainable limits, risking severe ecological and societal effects.
Future Considerations:
- Sustainability Challenges: Managing resources sustainably requires shifts in consumption, efficient use, and eco-friendly innovations.
- Policy and Planning: Strategic policies should promote renewable energy, recycling, waste management, and biodiversity preservation.
2.1.14 Carrying capacity cannot be easily assessed for human populations.
- Explain why 'carrying capacity' why caring capacity is a challenge to calculate
- Explain how technological advancements can alter the perceived carrying capacity of a region
Key Ideas on Human Carrying Capacity
Key Factors Influencing Human Carrying Capacity:
Implications for Sustainability:
Calculating Carrying Capacity with Ecological Footprints:
- Unique Challenges in Calculating Carrying Capacity:
- Human populations present complex challenges due to constantly changing ecological interactions and resource usage.
Key Factors Influencing Human Carrying Capacity:
- Human Ecological Niche:
- Expansive and Evolving: Unlike other species, humans continuously expand and adapt their niche through technological innovations (e.g., agriculture, digital technology).
- Resource Mobility: Humans can transport resources globally, bypassing local resource limits and complicating carrying capacity calculations.
- Technological Impact:
- Expanding Capacity: New technologies (e.g., desalination) allow access to resources once unavailable, temporarily increasing carrying capacity.
- Consumption Patterns: Increased resource consumption, especially in developed countries, intensifies resource demands and environmental impacts.
- Fluctuating Human Habitats:
- Changing Environments: Urbanization, deforestation, and climate change alter the environmental conditions that influence carrying capacity.
- Contested Estimates: Estimates are often temporary, as technological and environmental changes rapidly shift the parameters for carrying capacity.
- Human Exceptionalism in Ecosystem Equilibrium:
- Natural Equilibrium: Most species stabilize near their environment’s carrying capacity due to natural checks (predation, disease).
- Human Alterations: Humans avoid these checks through medical, agricultural, and environmental modifications, avoiding natural population decline.
Implications for Sustainability:
- Sustainability Concerns: The difficulty in defining clear carrying capacity limits complicates sustainable planning, risking resource overexploitation and ecological harm.
- Future Solutions: Multidisciplinary approaches and international cooperation are essential for managing resources sustainably and addressing the complexity of human carrying capacity.
Calculating Carrying Capacity with Ecological Footprints:
- Ecological Footprint: Quantifies the land and water area needed to sustain a population’s resource consumption and waste absorption.
- Carrying Capacity Estimate: Calculated as the reciprocal of the ecological footprint, offering a measure of how many people an area can sustain based on current consumption.
This video discusses the idea of r and K strategy organisms. This is an HL topic. However the rest of this video does great job in discussing key point human carrying capacity.
measuring populations
2.1.15 Population abundance can be estimated using random sampling, systematic sampling or
transect sampling.
transect sampling.
- Define random sampling, systematic sampling' , and transect sampling
- Explain how transect sampling can be used to assess biodiversity along an environmental gradient.
- Describe the process of random sampling
- Analyze the benefits and drawbacks of using belt transects over line transects in a forest ecosystem study.
Estimating the abundance of a population within an ecosystem is essential for ecological research, conservation efforts, and resource management. Various sampling methods are employed to estimate population size and density, each with its own advantages and specific applications. Here, we explore three primary sampling techniques: random sampling, systematic sampling, and transect sampling.
Random Sampling
- Description: Random sampling involves selecting random points or areas in a habitat to collect data on the species of interest. This method is used to avoid bias in the selection process and to ensure that every individual in the population has an equal chance of being included in the sample.
- Application: It is particularly useful in homogeneous environments where the distribution of the population is uniform. Researchers might use random number tables or computer-generated random coordinates to determine sampling locations.
Systematic Sampling
- Description: Systematic sampling involves selecting samples from a fixed interval along a grid or predetermined path within the study area. This method is more structured compared to random sampling and ensures that the sampled area is evenly covered.
- Application: Commonly used in environments where species are evenly distributed across a landscape or in agricultural studies where crops are planted in uniform rows.
https://wormwatch.d.umn.edu/research/research-methods/sampling-transects
Transect Sampling:
- Description: A line (transect) is placed across a habitat, and organisms along the line are sampled to study how physical factors like temperature and light affect distribution. Environmental gradients, such as moving away from a stream or up a mountain, influence these changes.
- Types:
- Line Transect: Observations made along a line.
- Belt Transect: Observations made in a strip of a certain width for larger samples.
- Application: Useful for studying species distribution across environmental gradients (e.g., from shore to deeper lake areas).
- Advantages: Analyzes spatial patterns along gradients.
- Limitations: May not represent the entire habitat in heterogeneous environments.
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Integrating Sampling Techniques: In practice, ecologists often combine these sampling methods to compensate for their individual limitations and to enhance the reliability of their population estimates. For instance, systematic transects might be randomly placed within a larger study area to gather comprehensive data across diverse environmental conditions.
2.1.16 Random quadrat sampling can be used to estimate population size for non-mobile
organisms.
organisms.
- Explain the use of quadrats for estimating the abundance of non-motile organisms through making actual counts, measuring population density, percentage cover and percentage frequency
- Representative Sampling: Field ecologists often use smaller, manageable areas that reflect larger ecological patterns. This approach is essential since it’s impractical to observe every individual or square meter in a habitat.
- Quadrat Sampling:
- Purpose: Commonly used to study biodiversity and species distribution.
- Method: Quadrats—square frames, often made of wire—are placed randomly or systematically within a habitat. Species within each quadrat are identified and counted.
- Structure: Quadrats may be divided into smaller grids (e.g., 5 × 5 or 10 × 10 squares) to aid in more precise counts.
- Usage: Primarily used for stationary organisms like plants, though also applicable to slow-moving animals such as slugs and snails.
Quadrat Sampling
- Counts
- Number of species in an individual area
- Population Density
- The number of individuals per unit area
- Once you know the number of individuals it is a simple calculation to establish the population density
- D=ni/A (D = density; n = number of individuals in species, A = sampling area)
- Percent Coverage
- The proportion of ground that is occupied or area covered by the plant/species
- Easily assessed if the quadrat is subdivided into 100 smaller squaresCi=ai/A
- Percent Frequency
- The number of times a given event occurs
- How often a particular species appears in an area.
- Best done with a gridded quadrat
Application of skills: Use quadrat sampling estimates for abundance, population density, percentage cover and percentage frequency for non-mobile organisms and measures change along a transect.
Severals examples of applying quadrat sampling techniques in urban and peri-urban environments around Atlanta, Georgia. These activities can provide valuable insights into urban ecology, land use impacts, and conservation efforts within the city and its surrounding areas:
- Example 1: Urban Tree Canopy Assessment: Select several neighborhoods with varying levels of urbanization and green space. Use quadrats in designated parks and street green belts to measure tree abundance and canopy cover. Analyze data to identify areas with lower tree density and propose urban planning solutions to enhance green coverage.
- Example 2: Invasive Plant Species Monitoring in Piedmont Park: Lay out a transect line that covers various parts of the park, including wooded areas and open fields. Use quadrats to estimate the percentage cover and frequency of invasive species. Document the spread and develop management strategies to control or eradicate invasive species, promoting native biodiversity.
- Example 3: Pollinator Habitat Evaluation in Community Gardens: Identify community gardens that use different types of vegetation. Place quadrats randomly within these gardens to assess the percentage cover of flowering plants and the presence of pollinators. Evaluate which types of gardens and plant species are most beneficial for pollinators, providing guidelines for garden planning and maintenance.
- Example 4: Surface Water Quality Assessment Along Chattahoochee River: Use systematic sampling along different points of the river within the city limits. Assess abiotic factors such as water pH, dissolved oxygen, and salinity using portable testing kits. Correlate the presence of urban pollutants with changes in water quality indicators to assess the health of the river and the effectiveness of current pollution control measures.
- Example 5: Green Roof Biodiversity Study in Downtown Atlanta: Select several buildings with green roofs and establish transects across each roof. Use quadrats to record the types and abundance of both plants and visiting insects. Determine the ecological value of green roofs and suggest improvements for increasing urban biodiversity and ecological connectivity.
2.1.17 Capture–mark–release–recapture and the Lincoln index can be used to estimate population
size for mobile organisms.
size for mobile organisms.
- Identify the types of direct and indirect methods
- Apply the use of the Lincoln index
It is impossible for you to study every organism in an ecosystem. The number of organisms can be overwhelming. Limitations must be put on how many plants and animals you study. In order to study the animals there are trapping methods which help obtain more samples, like:
small mammal trap
collecting nets
 https://www.amentsoc.org
Tullgren funnel
 https://www.mdpi.com/2072-4292/11/11/1308
Aerial photography or satellite
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 https://www.bnhs.co.uk/youngnats/to-do/build-a-pitfall-trap/
pooter
 https://www.indiamart.com/
Light trap
Kck sampling
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It must be remembered that any method used to capture the animal must be as harmless as possible. Completely harmless capture is unlikely but there are some techniques that are less harmful. There are numerous humane techniques to catch animals for study then release them.
Lincoln Index
The Lincoln Index is an indirect method by which the size of an animal population can be estimated. It is also called the capture/mark/release/recapture method
Lincoln Index
The Lincoln Index is an indirect method by which the size of an animal population can be estimated. It is also called the capture/mark/release/recapture method
- Capture: In your area of study, capture as many of the study animals as possible in a fixed time period. Record the number that you have caught.
- Mark: Mark the captured organisms in a way that does not harm them or make them more or less prone to predation.
- Release: Release the animals back into their environment and give them sufficient time to reintegrate into the population. Fast moving animals like mice will reintegrate more quickly than slow-moving animals like snails.
- Recapture: Capture a second sample of the population using the same fixed time period used for the first capture. Record the total number of animals that you have caught in the second sample. Include the number of marked animals. You can now estimate the size of the population.
– n1 is the number caught in the first sample
– n2 is the number caught in the second sample
– nm is the number caught in the second sample that were marked
– n2 is the number caught in the second sample
– nm is the number caught in the second sample that were marked
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Assumptions of Lincoln Index:
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Issues Associated with Lincoln Index
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Application of skills: Students should use the Lincoln index to estimate population size.
Students should understand the assumptions made when using this method.
Students should understand the assumptions made when using this method.
Example 1: Estimating Fish Populations in a Local Pond
This simulation involves using beans as a stand-in for a population of animals.
- Students can capture fish using nets, mark them with non-toxic, visible tags, and release them. After a set period, another round of capture is conducted to count how many marked fish are recaptured.
- Capture a number of squirrels, mark them with harmless dye or collars, and release them. After some days, perform another capture session to see how many marked squirrels are found.
- Students can use ecological software or an online simulation tool to model an insect population, applying the Lincoln Index method to estimate population size. Parameters can be adjusted to see how changes affect the reliability of the estimate.
- Trap a number of mice, mark them using non-toxic paint on their fur, and then release them. After a period, re-trap to determine how many marked mice are captured.
- Using hypothetical data or a digital simulation, students can mark, release, and recapture virtual birds, analyzing how different capture rates and marking visibility affect population estimates.
This simulation involves using beans as a stand-in for a population of animals.
communities and ecosystems
2.1.18 A community is a collection of interacting populations within the ecosystem.
- Define community with reference to a named example
A community consists of various populations of different species living and interacting in a defined area at a specific time. Interactions include competition, predator-prey dynamics, and mutualistic relationships essential for nutrient cycling and population balance.
Community Stability and Biodiversity:
Community Stability and Biodiversity:
- High-Diversity Communities:
- Feature a variety of species with complex, interconnected food webs.
- Resilience: These communities are more resilient to disturbances. If one species is lost, others with similar ecological roles can help maintain stability.
- Low-Diversity Communities:
- Comprise fewer species, resulting in simpler food webs.
- Vulnerability: With fewer species to fulfill roles, the removal of a single species has a more significant impact, making these communities more susceptible to environmental changes.
Local Community: Okefenokee Swamp, Georgia, USA
https://members.wetlandsofdistinction.org/woddirectory/Details/okefenokee-swamp-2383655
The Okefenokee Swamp is one of the largest intact freshwater wetlands in North America, located in southeastern Georgia, USA. This vast peat-filled wetland hosts a rich mosaic of boggy islands, lakes, and forests.
Community Interactions: The swamp supports a diverse community of plants and animals, including over 400 species of vertebrates like alligators, sandhill cranes, and a variety of fish and amphibian species. This biodiversity is crucial for the swamp’s ecological stability.
Ecological Roles and Interactions:
Resilience to Disturbance:
The Okefenokee’s complex food web and multiple habitat types make it resilient to disturbances. For instance, water level fluctuations, which might devastate a less diverse wetland, are buffered by the swamp’s varied community structure, allowing species to find refuge and resources even during extreme conditions.
Resilience to Disturbance:
Understanding the dynamics of ecological communities like those in the Okefenokee Swamp is crucial for effective conservation efforts. Protecting areas of high ecological diversity is vital not only for the preservation of species but also for maintaining the ecological services that these communities provide. Conservation strategies should focus on preserving and restoring habitat diversity to ensure the stability and resilience of local ecosystems.
Community Interactions: The swamp supports a diverse community of plants and animals, including over 400 species of vertebrates like alligators, sandhill cranes, and a variety of fish and amphibian species. This biodiversity is crucial for the swamp’s ecological stability.
Ecological Roles and Interactions:
- Alligators act as a keystone species, modifying the aquatic habitat to create alligator holes that provide critical water pools during dry spells, benefiting a variety of aquatic organisms.
- Carnivorous plants like pitcher plants and sundews thrive in the nutrient-poor soils, capturing insects to supplement their nutritional intake, which demonstrates a unique adaptation within the community.
- Tree diversity, including cypress and pine, supports varied bird populations by offering nesting sites and food sources.
Resilience to Disturbance:
The Okefenokee’s complex food web and multiple habitat types make it resilient to disturbances. For instance, water level fluctuations, which might devastate a less diverse wetland, are buffered by the swamp’s varied community structure, allowing species to find refuge and resources even during extreme conditions.
Resilience to Disturbance:
Understanding the dynamics of ecological communities like those in the Okefenokee Swamp is crucial for effective conservation efforts. Protecting areas of high ecological diversity is vital not only for the preservation of species but also for maintaining the ecological services that these communities provide. Conservation strategies should focus on preserving and restoring habitat diversity to ensure the stability and resilience of local ecosystems.
2.1.19 Habitat is the location in which a community, species, population or organism lives.
- Define habitat
image from www.britannica.com
A habitat is the specific environment where a community, species, population, or individual resides, providing essential resources like food, water, shelter, and mates. Habitat requirements reflect a species’ ecological niche and influence its distribution.
Components of a Habitat:
Be aware that for some organisms, habitats can change over time as a result of migration.
Components of a Habitat:
- Geographical Location: Refers to the physical area where the species lives, such as a forest, river, or coastal area.
- Physical Conditions: Includes key environmental factors like temperature, humidity, soil type, water depth, and light, crucial for species survival.
- Ecosystem Type: The kind of ecosystem—desert, wetland, forest, etc.—provides the habitat’s structural and ecological framework, supporting species adapted to those specific conditions.
Be aware that for some organisms, habitats can change over time as a result of migration.
Habitat in a Local Ecosystem: Blue Ridge Mountains, Georgia
https://earthathome.org/hoe/se/topography-brp/
The Blue Ridge Mountains in Georgia are part of the Appalachian Mountain range, characterized by their vast deciduous forests, high biodiversity, and the range of altitudes offering varied climatic conditions.
Habitat description and Its Importance in understanding and describing a habitat in detail is essential for conservation efforts. It helps in:
- Flora and Fauna: This region provides habitats for a diverse array of species. For instance, the American black bear (Ursus americanus) inhabits these mountains, utilizing the dense forests for shelter and the abundant berry bushes and other food sources for nutrition.
- Habitat Specifics:
- Forests: Provide cover and nesting sites for numerous bird species, small mammals, and insects.
- Streams and Rivers: Serve as habitats for aquatic species like the native brook trout, which require cold, clear, oxygen-rich water and specific breeding conditions.
- Meadows and Clearings: Support wildflowers that attract pollinators, including bees and butterflies, and serve as feeding grounds for herbivores like deer.
- Conservation Considerations: The conservation of habitats in the Blue Ridge Mountains focuses on maintaining forest health, controlling invasive species, protecting water quality, and ensuring connectivity between habitats to support wildlife corridors for species migration and genetic exchange.
Habitat description and Its Importance in understanding and describing a habitat in detail is essential for conservation efforts. It helps in:
- Species Conservation: Specific habitat needs must be met to conserve endangered species. For example, protecting nesting sites for birds or denning areas for bears.
- Ecosystem Management: Effective management practices ensure that various habitat requirements for different species are maintained, enhancing biodiversity and ecosystem stability.
2.1.20 Ecosystems are open systems in which both energy and matter can enter and exit.
- Explain how energy flows and matter cycles contribute to the sustainability of an ecosystem
- Describe the role of biodiversity in maintaining the sustainability of ecosystems.
An ecosystem includes all living organisms (biotic community) and the physical environment (abiotic factors) such as air, water, and soil. Ecosystems operate as open systems, where energy and matter flow in and out continuously.
Dynamics of Energy and Matter:
Dynamics of Energy and Matter:
- Energy Flow:
- Source: Energy enters primarily as sunlight, captured by producers (autotrophs) via photosynthesis.
- Transfer: Energy moves through trophic levels—from producers to consumers and decomposers—and exits as heat during metabolic processes.
- Matter Cycling:
- Nutrient Cycles: Nutrients like carbon, nitrogen, and phosphorus cycle within the ecosystem.
- Role of Decomposers: Decomposers recycle nutrients from dead organisms back into the environment, enabling reuse by producers and maintaining ecosystem health.
Local Ecosystem: Chattahoochee River National Recreation Area
The Chattahoochee River National Recreation Area, flowing through the Atlanta metropolitan area, serves as a vital ecosystem comprising riverine and terrestrial habitats.
Energy Inputs and Outputs:
Matter Dynamics:
Biological Interactions:
Conservation and Management:
Understanding the open system nature of ecosystems like the Chattahoochee River is crucial for effective conservation and management:
Energy Inputs and Outputs:
- Solar Energy: Sunlight penetrates the water and is used by aquatic plants and algae to produce energy-rich organic compounds.
- Heat Energy: Energy is lost from the ecosystem as heat during respiration by plants, animals, and microbes.
Matter Dynamics:
- Water Flow: The river transports nutrients and organic matter along its course, influencing the distribution and productivity of aquatic and riparian communities.
- Sediment Transport: Sediments carried by the river contain organic and inorganic matter, shaping the physical landscape and providing nutrients downstream.
Biological Interactions:
- Aquatic Plants: Utilize dissolved nutrients and light for growth, serving as the primary producers.
- Fish Populations: Serve as consumers, feeding on insects, smaller fish, and plant matter. They are integral to transferring energy to higher trophic levels, including birds and mammals.
- Decomposers: Bacteria and fungi break down organic waste and dead materials, releasing nutrients back into the water and soil, completing the nutrient cycle.
Conservation and Management:
Understanding the open system nature of ecosystems like the Chattahoochee River is crucial for effective conservation and management:
- Pollution Control: Efforts must ensure that contaminants do not enter the ecosystem through water or air, disrupting the delicate balance of energy and matter cycling.
- Habitat Conservation: Protecting the riparian zones and aquatic habitats helps maintain natural matter and energy flows, supporting diverse wildlife and plant communities.
- Sustainable Practices: Activities such as regulated fishing, controlled water use, and habitat restoration are essential to preserve the ecological integrity and ensure the continued provision of ecosystem services.
2.1.21 Sustainability is a natural property of ecosystems.
- Define sustainability
- Explain how energy flows and matter cycles contribute to the sustainability of an ecosystem.
- Describe the role of biodiversity in maintaining the sustainability of ecosystems.
Ecosystems maintain a balance of inputs and outputs, allowing them to endure over long periods. This balance enables ecosystems like tropical rainforests to remain stable and resilient despite disturbances.
Key Components of Ecosystem Balance:
Key Components of Ecosystem Balance:
- Inputs:
- Energy: Sunlight is the primary energy source for ecosystems.
- Nutrients: Absorbed from soil or water, nutrients sustain various organisms.
- Other Inputs: Water through precipitation and organic matter from internal or external sources.
- Processes:
- Photosynthesis: Plants convert solar energy into chemical energy, which supports food chains.
- Nutrient Cycling: Organic matter decomposes, returning nutrients to the ecosystem for reuse.
- Outputs:
- Respiratory Heat: Heat loss from organisms through respiration.
- Decomposition: Breaks down organic material, releasing nutrients.
- Transpiration: Water loss through plant leaves, helping regulate ecosystem moisture.
Example: Tropical Rainforests
Tropical rainforests are among the oldest and most stable ecosystems on Earth. They are incredibly resilient due to their high biodiversity and complex trophic interactions.
Tropical rainforests are among the oldest and most stable ecosystems on Earth. They are incredibly resilient due to their high biodiversity and complex trophic interactions.
- Flow Diagram Components:
- Inputs: High levels of rainfall, abundant sunlight, and a rich supply of decomposed organic material.
- Processes: Intense photosynthetic activity, rapid nutrient cycling due to warm temperatures and moist conditions, and diverse food web interactions.
- Outputs: High levels of oxygen production, heat energy from dense vegetation, and continuous leaf litter contributing to soil nutrient content.
Resilience and Disturbances:
- Ecosystems, like tropical rainforests, are vulnerable to disturbances such as deforestation, climate change, and pollution. Their resilience—ability to recover—depends on biodiversity and strong nutrient cycles and energy flows.
- Biodiversity: Provides multiple species with similar roles, allowing the ecosystem to maintain function even if some species are impacted.
- Storage Capacity: Large biomass and nutrient storage help sustain ecological processes during disruptions.
- Sustainable management practices, like conservation, resource management, and pollution control, are essential to protect ecosystems and maintain their balance.
2.1.22 Human activity can lead to tipping points in ecosystem stability.
- Define 'tipping point'
- Explain how human activities can push ecosystems towards tipping points
- Describe the consequences of reaching a tipping point in a major ecosystem like the Amazon rainforest.
Human activities often drive ecosystems toward tipping points, where small changes can cause irreversible shifts, disrupting stability and altering ecosystem functionality.
Key Concepts:
Direct Human Impacts on Biodiversity:
Indirect Human Impacts on Biodiversity:
Implications for Conservation:
Key Concepts:
- Tipping Points:
- Definition: Critical thresholds where minor changes trigger significant, often irreversible shifts in ecosystem states.
- Mechanism: Feedback loops amplify disturbances, potentially leading to ecosystem collapse and new, less stable equilibriums.
- Biosphere Integrity:
- Encompasses species and genetic diversity, and ecosystem functions, all crucial for Earth's resilience to environmental change.
- Planetary Boundaries: Human pressures, including deforestation, pollution, and climate change, push the biosphere toward boundaries that, if crossed, could destabilize ecosystems on a regional or global scale.
Direct Human Impacts on Biodiversity:
- Overharvesting: Excessive resource extraction (e.g., overfishing) disrupts food chains and lowers biodiversity.
- Poaching and Illegal Trade: Decimate populations of species, like elephants for ivory, undermining ecosystem stability.
Indirect Human Impacts on Biodiversity:
- Habitat Loss: Land conversion for agriculture and urbanization destroys habitats, reducing biodiversity.
- Climate Change: Alters habitats, shifts species ranges, and drives local extinctions.
- Pollution: Industrial and agricultural pollution harms ecosystems, degrading habitats and endangering species.
- Invasive Species: Introduced species often outcompete native species, disrupting local ecosystems due to the absence of natural predators.
Implications for Conservation:
- Monitoring and Management: Tracking tipping points allows for proactive measures to prevent irreversible ecosystem shifts.
- Sustainable Practices: Measures like sustainable agriculture, reforestation, and stricter deforestation laws help maintain ecological balance and reduce risks of reaching tipping points.
https://www.snexplores.org/article/why-amazon-rainforest-in-trouble-climate-deforestation
Deforestation in the Amazon Rainforest:
- Process of Change: The Amazon regulates the global climate by producing water vapor through transpiration, influencing precipitation patterns.
- Impact of Human Activity: Large-scale deforestation disrupts transpiration, reducing rainfall and affecting climate, potentially creating a feedback loop that accelerates forest loss.
- New Equilibrium: Continued deforestation may push the rainforest to a tipping point, transforming it into a savannah-like ecosystem with drastically reduced biodiversity.
2.1.23 Keystone species have a role in the sustainability of ecosystems.
- Define 'keystone species'
- Explain keystone species role in an ecosystem
- Explain how the removal of a keystone species can lead to ecosystem collapse, using the example of purple sea stars
- Describe the effects of elephants on savannah ecosystems and how they qualify as a keystone species.
Keystone Species:
- Keystone species play a vital role in maintaining ecosystem structure and diversity. Despite their smaller numbers, they regulate populations, support ecological processes, and enhance habitat diversity, critical for ecosystem resilience.
- Population Control: Species like gray wolves control herbivore populations, preventing overgrazing and supporting vegetation and food webs.
- Habitat Modification: Beavers create wetlands by building dams, providing habitats for various species and boosting biodiversity.
- Trophic Cascades: Loss of predators, like wolves, leads to overpopulation of prey (e.g., deer), causing ecological degradation.
- Habitat Changes: Loss of herbivores (e.g., elephants) can alter ecosystems, reducing biodiversity and affecting fire regimes.
- Biodiversity Loss: Keystone species extinction decreases ecosystem diversity, disrupting food webs and habitat formation.
- Protecting keystone species sustains biodiversity and ecosystem services, essential for both wildlife and humans. Conservation efforts should prioritize their protection to prevent ecological collapse.
https://www.niabizoo.com/animals-habitats-details/purple-sea-star/
Examples of Keystone Species
Exploring Purple Sea Stars at HHMI
- Purple Sea Stars (Pisaster ochraceus):
- Role: These sea stars are crucial in maintaining the balance of intertidal ecosystems along the North Pacific coast by preying on mussels.
- Impact: Without purple sea stars, mussel populations could expand uncontrollably, monopolizing space and resources and thereby reducing the diversity of intertidal zones.
Exploring Purple Sea Stars at HHMI
African Elephants (Loxodonta africana):
- Role: Elephants help maintain savannah ecosystems by feeding on trees and shrubs, thus preventing these plants from encroaching on grasslands.
- Impact: This feeding behavior helps preserve open grassland habitats essential for many other savannah species, including grazing animals like wildebeests and zebras, and their predators.
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Human Interactions with Ecosystems
2.1.24 The planetary boundaries model indicates that changes to biosphere integrity have passed a
critical threshold.
critical threshold.
- Describe the consequences of exceeding the planetary boundary for biosphere integrity on global biodiversity
- Explain how human activities have led to the crossing of the planetary boundary for biosphere integrity
https://www.stockholmresilience.org/research/planetary-boundaries.html
The Planetary Boundaries model defines safe limits for human activity to prevent irreversible environmental damage, with biosphere integrity as a key component. Recent evidence suggests that human actions have pushed this boundary past safe limits.
Overview of Biosphere Integrity:
Impacts on Ecosystems and Species Diversity:
Conservation and Restoration Efforts:
Example: Impact on Food Webs
Overview of Biosphere Integrity:
- Definition: Refers to the health and stability of species populations, genetic diversity, and ecosystem functionality, essential for supporting life on Earth.
- Threshold Breach: The boundary for biosphere integrity has been crossed due to human-induced pressures like habitat destruction, pollution, overexploitation, and invasive species.
Impacts on Ecosystems and Species Diversity:
- Loss of Species: Extinction rates are far above natural levels; around 70% of vertebrate populations have declined from 1973 to 2023.
- Insect Decline: Insect populations are decreasing by approximately 2% annually, jeopardizing pollination, nutrient cycling, and food webs.
- Ecosystem Vulnerability: Reduced biodiversity weakens ecosystem resilience, making them more susceptible to other stressors like climate change, thus threatening global ecosystem stability.
Conservation and Restoration Efforts:
- Monitoring and Mitigation: Effective strategies include habitat protection, enforcing wildlife laws, and sustainable land and resource management.
- Restoration Projects: Initiatives such as reforestation, wetlands restoration, and reintroducing native species can rebuild ecological networks and enhance biodiversity, improving ecosystem resilience.
Example: Impact on Food Webs
- Role of Insects: As primary pollinators and a significant food source for higher trophic levels, the decline in insect populations jeopardizes the entire structure of food webs, potentially leading to further losses in biodiversity and ecosystem collapse.
2.1.25 To avoid critical tipping points, loss of biosphere integrity needs to be reversed.
- Explain how maintaining ecosystem integrity can help avoid ecological tipping points.
- Describe the relationship between ecosystem protection and the preservation of species' niche requirements
The loss of biosphere integrity threatens ecosystems with irreversible damage, making protection and restoration essential for long-term sustainability.
Importance of Ecosystem Protection:
Strategies for Reversing Ecosystem Damage:
Long-Term Benefits:
Examples of Ecosystem Protection:
Importance of Ecosystem Protection:
- Preventing Tipping Points: Ecosystems can endure some stress, but crossing critical thresholds may lead to irreversible collapse.
- Maintaining Niches: Species rely on specific conditions within their ecological niches for survival. Protecting ecosystems helps preserve these environments, ensuring species have access to essential resources.
Strategies for Reversing Ecosystem Damage:
- Habitat Conservation: Establishing protected areas, restoring degraded habitats, and adopting sustainable land-use practices are key to minimizing environmental impact.
- Biodiversity Preservation: Supporting species diversity and genetic variation enhances ecosystem resilience and adaptability.
- Pollution Control: Reducing pollutants through waste management, cleaner production, and restricted use of hazardous materials lessens human ecological impact.
- Regeneration Strategies: Active restoration (e.g., rewilding, afforestation, wetland revival, soil improvement) promotes biodiversity and improves ecosystem functions in degraded areas.
Long-Term Benefits:
- Sustainable Resource Use: Protecting ecosystem integrity enables resource use that meets current needs without jeopardizing future availability.
- Climate Regulation: Ecosystems like forests, wetlands, and oceans play critical roles in carbon sequestration and climate stability.
- Enhanced Human Well-being: Healthy ecosystems provide vital services like clean air and water, foundational to human health and economic stability.
Examples of Ecosystem Protection:
- Marine Reserves: Restricting extractive activities in designated ocean areas aids in fish stock recovery and coral reef protection.
- Forest Conservation Programs: Sustainable forestry and anti-deforestation efforts help maintain forest cover, benefiting climate regulation, biodiversity, and local livelihoods.
Case Study: Everglades Restoration Project Overview
https://gisgeography.com/everglades-national-park-map/
https://fl.audubon.org/
The Florida Everglades, often called the "River of Grass," covers millions of acres and is a mosaic of freshwater ponds, prairies, and forested uplands. Historical efforts to drain the marshes for agriculture and urban development drastically altered the landscape, leading to significant loss of wildlife habitat, declining water quality, and endangered species.
Comprehensive Everglades Restoration Plan (CERP)
The Comprehensive Everglades Restoration Plan (CERP), authorized by Congress in 2000, is the world’s largest ecological restoration project. It seeks to restore, protect, and preserve central and southern Florida’s water resources, focusing on the Everglades.
Goals and Strategies:
Impacts and Outcomes:
Challenges:
The Comprehensive Everglades Restoration Plan (CERP), authorized by Congress in 2000, is the world’s largest ecological restoration project. It seeks to restore, protect, and preserve central and southern Florida’s water resources, focusing on the Everglades.
Goals and Strategies:
- Water Capture and Redirection: CERP aims to capture fresh water that would otherwise flow to the ocean, redirecting it to areas in need.
- Key Objectives:
- Water Storage: Increase water storage to support the ecosystem and communities.
- Water Quality: Improve water quality to reduce algal blooms and ecological distress.
- Ecosystem Restoration: Restore natural areas by removing invasive species, replanting native vegetation, and constructing barriers to manage water flow.
Impacts and Outcomes:
- Biodiversity: Positive signs, such as the recovery of American crocodile and manatee populations, have been observed.
- Water Quality: Notable improvements in water quality have helped reduce harmful algal blooms.
Challenges:
- Funding and Politics: The project faces obstacles like funding shortages and political challenges.
- Climate Change: Warming temperatures and rising sea levels add complexity to long-term restoration efforts.
HL Only
The HL unit will take a minimum of 3 hours.
2.1.26 There are advantages of using a method of classification that illustrates evolutionary relationships in a clade.
- Define 'clade' and 'cladogram'
- Explain how cladistic classification helps in understanding evolutionary relationships among species
- Describe how DNA sequencing has influenced the reclassification of species within modern taxonomy.
Cladistics is a classification method that maps evolutionary relationships, showing how species are related through a common ancestor. This approach focuses on a clade, which includes an ancestor and all its descendants.
Overview of Cladistics:
Overview of Cladistics:
- Cladogram Utilization:
- A cladogram is a diagram that visually represents evolutionary relationships among species based on shared traits.
- Cladograms illustrate paths of evolutionary divergence, grounded in the principle of common ancestry.
- Evolutionary Insight:
- Cladistics provides a "tree of life" visual, where each branch represents a distinct lineage with unique evolutionary traits.
- By examining shared characteristics, cladistics highlights the evolutionary paths and adaptations that led to the diversity of species today.
Benefits of Cladistic Classification
Application in Modern Taxonomy:
DNA Sequencing in Modern Classification:
- Accuracy in Evolutionary Relationships:
- Cladistics focuses on common ancestry, offering a more accurate representation of evolutionary pathways compared to traditional classification methods based solely on shared physical traits.
- Revealing True Lineages:
- Advances in genetics have refined cladistic analysis, revealing misclassifications in traditional systems (e.g., the red panda’s reclassification).
- Insights into Evolutionary Changes:
- Cladograms reveal trait origins, adaptations, and extinctions within lineages, essential for understanding species’ evolutionary adaptations.
Application in Modern Taxonomy:
- Testing Hypotheses:
- Cladistics provides a structured approach for testing hypotheses on evolutionary trait development and adaptability in different environments.
- Guiding Conservation Efforts:
- Understanding evolutionary relationships aids conservation by prioritizing ecosystems and clades, not just individual species, for preservation.
DNA Sequencing in Modern Classification:
- Discovery of New Species:
- DNA sequencing has uncovered previously unknown species, like a new Amazon frog species discovered in 2016.
- Reclassification of Species:
- Genetic analysis has corrected classification errors, such as reclassifying some fish from tuna to mackerel, based on closer evolutionary relationships.
https://www.researchgate.net/figure/Cladogram-from-vonHoldt-et-al-2010-depicting-the-structure-of-domestic-dog-breeds-as_fig1_263165803
Example of a Cladistic Approach
- Consider the use of a cladogram to study the evolutionary history of canines, which traces back to a common ancestor and branches out to various species like wolves, foxes, and domestic dogs. This cladogram would highlight the shared traits inherited from the ancestor and the unique adaptations that emerged in different environments.
2.1.27 There are difficulties in classifying organisms into the traditional hierarchy of taxa.
- Define 'binomial nomenclature'
- Explain binomial nomenclature's significance in biological classification.
- Analyze the limitations of using physical characteristics alone for classifying organisms
https://materchristi.libguides.com/habitats_interactions/classification
- Traditional Classification:
- Developed by Carl Linnaeus, this system categorizes organisms hierarchically (kingdom, phylum, class, etc.) based on physical traits.
- Limitations: Physical similarities don’t always indicate close evolutionary relationships, leading to potential misclassifications.
- Challenges in Traditional Classification:
- Misalignment with Evolution: Organisms grouped by appearance may not be closely related. Genetic data has shown discrepancies, prompting reclassification.
- Example: Species once grouped by physical traits or reproductive features have been reclassified based on genetic evidence.
- Impact of Molecular Biology:
- DNA Sequencing: Reveals deeper genetic relationships, enhancing classification accuracy.
- Phylogenetics: Builds evolutionary trees from genetic data, clarifying species divergence and evolutionary paths.
- Modern Approaches:
- Integrated Classification: Combines traditional morphology with genetic data for a more accurate understanding of biodiversity.
- Dynamic Nature: Taxonomy evolves with new genetic findings, keeping classifications in line with current scientific knowledge.
2.1.28 The niche of a species can be defined as fundamental or realized.
- Define 'fundamental niche' and 'realized niche'
- Explain how interspecific competition affects the realized niche of a species using an example from a known ecological study.
- Describe how the concepts of fundamental and realized niches could help in understanding the distribution patterns of two competing species in a given ecosystem
- Analyze the differences between the fundamental and realized niches of the barnacle species studied by Joseph Connell.
Every organism is adapted to environmental conditions in its habitat. However, it sometimes faces competition with other species that limits the conditions under which it can exist.
The ecological niche concept is crucial for understanding the distribution and behavior of species within their ecosystems. A niche reflects the range of conditions and resources a species can potentially utilize, along with its role in the ecosystem. This concept can be divided into two specific types: the fundamental niche and the realized niche.
The ecological niche concept is crucial for understanding the distribution and behavior of species within their ecosystems. A niche reflects the range of conditions and resources a species can potentially utilize, along with its role in the ecosystem. This concept can be divided into two specific types: the fundamental niche and the realized niche.
Fundamental Niche:
- The full range of environmental conditions a species could occupy without competition or other biotic constraints, based on its physiological limits and resource needs.
- The actual conditions where a species lives, constrained by interactions like competition and predation, representing how it adjusts to ecological pressures.
Case Study Examples1. Joseph Connell’s Barnacle Study:
- Background: Joseph Connell's classic study on barnacles demonstrated the distinction between fundamental and realized niches. He observed two barnacle species, Chthamalus stellatus and Balanus balanoides, on a rocky shore.
- Findings: Chthamalus stellatus could survive higher on the rocks beyond the reach of the tides—its fundamental niche. However, it primarily resides just above Balanus balanoides because of competitive exclusion—its realized niche.
image from www.quia.com
https://cns.utexas.edu/news/research/florida-lizards-evolve-rapidly-within-15-years-and-20-generations
Example 2. Brown and Green Anoles:
- Background: The study of brown anoles (Anolis sagrei) and green anoles (Anolis carolinensis) in Florida illustrates niche partitioning as a response to interspecific competition.
- Interactions: Initially, both anole species competed for similar resources. Over time, green anoles, primarily arboreal (tree-dwelling), moved higher into the trees, whereas brown anoles, being more ground-dwelling, dominated the lower vegetation and ground areas.
- Outcome: This adjustment shows the shift from their fundamental niches to realized niches due to competitive pressures, allowing both species to coexist by reducing direct competition.
2.1.29 Life cycles vary between species in reproductive behaviour and lifespan.
- Define 'r-strategist' and 'K-strategist'
- Explain how the life cycles of r-strategists and K-strategists are adapted to their respective environments.
- Discuss how changes in environmental conditions might affect the balance between r-strategists and K-strategists in a given ecosystem.
Life cycles and reproductive behaviors vary significantly across species, influenced by their environmental contexts and evolutionary adaptations. Two contrasting strategies, known as r-strategists and K-strategists, exemplify how species have adapted their life cycles to thrive under different ecological conditions and successional stages.
https://laurenschramm.com/2018/02/18/r-and-k-selected-species/
r-strategists:
- Species that reproduce quickly and in large numbers, thriving in unstable or unpredictable environments. They have short lifespans, rapid maturation, and produce many offspring with little parental care, maximizing reproductive success in high-mortality, variable conditions.
- Example: Insects and annual plants colonize disturbed areas, such as fields or post-fire landscapes, using available resources to quickly reproduce before conditions change.
https://laurenschramm.com/2018/02/18/r-and-k-selected-species/
K-strategists:
- Species adapted to stable environments with predictable resources and higher competition. They produce fewer offspring but invest heavily in each, ensuring higher survival rates. K-strategists have longer lifespans, slower development, and provide extensive parental care.
- Example: Elephants and humans, with few offspring, invest significant care to prepare them for survival in competitive environments.
Ecological Implications of Reproductive Strategies:
- Adaptation to Environmental Stability: K-strategists excel in stable ecosystems near carrying capacity, competing for limited resources, while r-strategists thrive in disturbed environments, reproducing rapidly to exploit temporary resource abundance.
- Successional Stages: r-strategists are early colonizers in ecological succession, while K-strategists dominate in mature, stable ecosystems as resources become more limited.
- Impact on Ecosystem Dynamics: The balance of r- and K-strategists affects ecosystem recovery and stabilization, critical for effective management in conservation and restoration efforts.
2.1.30 Knowledge of species’ classifications, niche requirements and life cycles help us to understand the extent of human impacts upon them.
- Define 'phenology'
- Explain the importance of phenology in understanding ecological responses to climate change.
- Explain how climate change can affect the life cycles of both plant and animal species
- Discuss the role of human activity in driving changes in the niches and classifications of species.
Human activities profoundly influence the natural world, affecting species' classifications, niche requirements, and life cycles. A comprehensive understanding of these elements is crucial for assessing the extent and implications of human-induced changes on biodiversity.
Human Impacts on Life Cycles
- Climate Change and Temperature Shifts: One of the most significant human impacts is through climate change, primarily caused by increased greenhouse gas emissions. Rising temperatures can alter the phenology (timing of life cycle events) of many species. For example, warmer springs can lead to earlier flowering in plants. This change, while subtle, can cascade through the ecosystem, affecting the life cycles of dependent species such as pollinators like bees and butterflies.
- Example: In some regions, the shift in plant flowering times has not matched the life cycle changes in pollinator species, leading to mismatches that can reduce food availability for these pollinators and affect plant reproduction success.
Disruption of Synchronized Life Cycles: Many species have life cycles that are intricately synchronized with those of other species and the seasonal cycles of their environments. As human-induced climate change shifts temperature patterns and seasonal timings, these synchronizations are disrupted. Animals that rely on specific plant species for food during certain life stages may find that these food sources are no longer available when needed.
- Example: In aquatic environments, temperature changes affect the breeding cycles of fish. Warmer water can accelerate development stages, leading to earlier spawning seasons. This change may not align with the hatching times of aquatic insects, a crucial food source for juvenile fish, impacting survival rates and population dynamics.
https://www.mdpi.com/2410-3888/8/6/319
Impact of Climate Change on Small Mammals
Small mammals, such as rodents and shrews, are particularly sensitive to changes in climate because their survival and reproductive success are closely tied to environmental conditions. Climate change can alter their habitats, food availability, and predator-prey dynamics, significantly affecting their life cycles.
Small mammals, such as rodents and shrews, are particularly sensitive to changes in climate because their survival and reproductive success are closely tied to environmental conditions. Climate change can alter their habitats, food availability, and predator-prey dynamics, significantly affecting their life cycles.
- Habitat Changes: As temperatures rise, the habitats suitable for small mammals may shift in altitude or latitude. For species that are not highly mobile or are habitat-specific, this can lead to population declines.
- Food Availability: The timing of food availability is crucial for small mammals, which often rely on seasonal cycles for food resources like seeds and insects. Climate change can disrupt these cycles, leading to food shortages during critical breeding or overwintering periods.
- Altered Hibernation and Breeding Cycles: Warmer winters and altered seasonal cues can disrupt hibernation patterns. This misalignment can lead to energy deficits and lower survival rates. Similarly, if breeding seasons shift due to temperature changes but do not align with food availability, it can affect the survival of offspring.
Broader Ecological Impacts
- Changes in Species Classifications and Niches: As environmental conditions change, the niches that species occupy can also shift. This may lead to changes in species distributions, with some species moving to cooler, higher altitudes or latitudes in response to temperature increases. Such shifts can introduce species to new competitors and predators, potentially leading to reclassifications of their ecological status.
- Example: Salmon and Mayflies
- Background: Salmon rely on the emergence of aquatic insects like mayflies for feeding their juveniles. Mayflies are sensitive to water temperature changes, which dictate their hatching times.
- Impact: With rising global temperatures, mayflies in many regions are emerging earlier in the spring. If this shift does not align with the salmon spawning period, juvenile salmon may experience a food shortage at a critical growth stage, impacting their survival and the population's health.
- Broader Ecological Impact: This misalignment can affect not only salmon but also other species within the food web, including predators of salmon and other aquatic and terrestrial animals dependent on mayflies.
- Example: Alpine Chipmunks
- Background: Alpine Chipmunks are adapted to cold mountainous environments. As temperatures rise, these species are forced to move to higher elevations in search of cooler climates.
- Impact: This upward migration introduces them to new ecological communities. For instance, alpine chipmunks encounter competitors and potential predators that were not present in their original lower-altitude habitats. This can lead to competitive exclusion, reduced genetic diversity, and even hybridization with closely related species.
- Conservation Implications: The change in altitude range and community dynamics may necessitate a reclassification of their conservation status and prompt targeted conservation strategies to preserve these species.
- Example: Salmon and Mayflies
- Impact on Biodiversity: The disruption of life cycles and niche shifts can have profound implications for biodiversity. As species adjust or fail to adjust to rapid environmental changes, some may become endangered or extinct, while others may thrive unexpectedly, leading to changes in community composition and ecosystem functions.
- Example: Coral Reefs
- Background: Coral reefs are highly sensitive to water temperature changes. Elevated sea temperatures lead to coral bleaching, where corals expel the algae (zooxanthellae) that give them color and nutrients.
- Impact: Severe bleaching events can lead to widespread coral death, disrupting the reef ecosystem — a biodiversity hotspot. The loss of coral reefs affects a myriad of species, from tiny invertebrates to large fish species, altering community structures and ecosystem functions.
- Long-term Effects: The decline of coral reefs demonstrates how temperature-induced changes in a keystone species' life cycle can ripple across an ecosystem, leading to potential collapses and significant
- Example: Coral Reefs
Key Terms
Correct use of terminology is a key skill in ESS. It is essential to use key terms correctly when communicating your understanding, particularly in assessments. Use the quizlet flashcards or other tools such as learn, scatter, space race, speller and test to help you master the vocabulary.
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biotic
abiotic niche transect sampling HL ONLY fundamental niche realized niche r-selected k-selected |
preditor
prey parasitism competition herbivory mutualism commensalism sustainability |
species
community population communities biosphere intraspecific interspecific interactions |
S-curve
J-curve organisms limiting factors tipping points biodiversity habitat cladogram |
ecology
ecosystem carrying capacity ecological footprint planetary boundaries keystone species population dynamics |
Classroom Material
| Subtopic 2.1 Individuals, Populations, Communities and Ecosystems Presentation.pptx |
| Subtopic 2.1 Individuals, Populations, Communities and Ecosystems Workbook.docx |
Activity 1: Know how to use dichotomous keys, applications and databases for the identification of species using the Salamander Dichotomous Key Activity
Activity 2: observe and record data on specific plant and animal species
Activity 3: Visit a local nature reserve or park to measure at least three abiotic factors in an aquatic or terrestrial ecosystem.
Activity 4: Identify two named examples in an ecosystem for each specific type of interaction between organisms. Species Interactions Activity
Activity 5: Use models that demonstrate feeding relationships, such as predator–prey
Activity 6: Reindeer of St Matthew Data Activity
Activity 7: Use quadrat sampling estimates for abundance, population density, percentage cover and percentage frequency for non-mobile organisms and measures change along a transect.
Activity 8: Use the Lincoln index to estimate population size.
Activity 9: Tipping point - visit the Resilience Alliance database
Activity 10: Research a keystone species that interests you
Activity: 11: Select a regeneration strategy such as rewilding, afforestation, wetland revival, or soil improvement through composting
HL
Activity 12: Research the evolutionary background of their assigned organisms, focusing on key traits and evolutionary milestones.
Activity 13: Produce a graphical summary of an example of niche partitioning
Activity 14: Research and describe the complete life cycle of your chosen species, emphasizing each stage from birth to reproduction. Identify specific human activities that impact the life cycle stages of the species.
Other possible activities
Exploring Species Activity
Carrying Capacity and Limiting Factor activity
Deer population graphing activity
Carrying Capacity and Bears in Alaska activity
Symbiosis Class Activity
Useful Links
The Nature Conservancy
National Geographic
WWF (World Wildlife Fund)
EPA (Environmental Protection Agency)
Biodiversity Heritage Library
iNaturalist
Global Biodiversity Information Facility (GBIF)
Encyclopedia of Life (EOL)
UNEP (United Nations Environment Programme)
Conservation International
Explore natural selection by controlling the environment and causing mutations in bunnies
The Nature Conservancy
National Geographic
WWF (World Wildlife Fund)
EPA (Environmental Protection Agency)
Biodiversity Heritage Library
iNaturalist
Global Biodiversity Information Facility (GBIF)
Encyclopedia of Life (EOL)
UNEP (United Nations Environment Programme)
Conservation International
Explore natural selection by controlling the environment and causing mutations in bunnies
| Click to Run |
In the News
World wildlife populations halved in 40 years - report - BBC News, 30 Sep 2014
Fast-growing fish species face greatest collapse risk - BBC News, 6 Aug 2015
World wildlife populations halved in 40 years - report - BBC News, 30 Sep 2014
Fast-growing fish species face greatest collapse risk - BBC News, 6 Aug 2015
TOK
- "To what extent do ethical considerations influence scientific practices in the study of ecosystems?"
International-mindedness
- Understanding and preserving the diversity and functionality of ecosystems requires a collaborative global effort that transcends national boundaries and cultural differences. As global citizens, it is our shared duty to respect and protect the natural world, recognizing that the health of our planet relies on the cooperative actions of all communities and cultures. This collective approach not only enriches our understanding of ecological systems but also ensures a sustainable environment for future generations worldwide.
Video Clips
Remarkable story of how the reintroduction of wolves to the Yellowstone National Park changed the ecology and habitat of the Park. There are many man-managed (or mismanaged) wildlife areas in the world missing predators.
Paul Andersen differentiates between biotic and abiotic factors. He explains how both abiotic and biotic factors can affect organisms at the level of the cell, the population and even the ecosystem. The complexities of biofilms, predator-prey relationships, and food webs are given as illustrative examples.
Species and populations
Paul Andersen explains the niche. He gives three different pronunciations and two different definitions. He then discusses the competitive exclusion principle and the idea that a niche cannot be shared by two species.
Interactions between species are what define ecological communities, and community ecology studies these interactions anywhere they take place. Although interspecies interactions are mostly competitive, competition is pretty dangerous, so a lot of interactions are actually about side-stepping direct competition and instead finding ways to divvy up resources to let species get along. Feel the love?
Exploring Science Looks at Symbiosis, Mutualism, Commensalism, and Parasitism
Different species often depend on one another. David Gonzales describes the remarkable relationship of the Clark's nutcracker and the whitebark pine, to illustrate the interdependency known as symbiosis.
Paul Andersen explains the differences between an r and a K selected species. He starts with a brief description of population growth noting the importance of; r or growth rate, N or number of individuals in the population, and K the carrying capacity. He describes three different survivorship curves found in organisms. He lists the characteristics of r-selected species like bacteria and K-selected species like humans.
