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Questions and Answers
What does community structure include?
What does community structure include?
Populations of all species in a specific geographic area.
Define disturbance in the context of ecology.
Define disturbance in the context of ecology.
Any relatively discrete event in time that disrupts ecosystem, community, or population structure and changes resources, substrate availability, or the physical environment.
What is succession?
What is succession?
The repeatable change in community composition through time following a disturbance.
Which model of succession applies only to secondary succession?
Which model of succession applies only to secondary succession?
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What is the climax community?
What is the climax community?
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Communities are almost always in equilibrium.
Communities are almost always in equilibrium.
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Disturbance creates ___________ diversity, which leads to species diversity.
Disturbance creates ___________ diversity, which leads to species diversity.
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What is the Intermediate Disturbance Hypothesis?
What is the Intermediate Disturbance Hypothesis?
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Which of the following are indirect interactions in ecology? (Select all that apply)
Which of the following are indirect interactions in ecology? (Select all that apply)
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Study Notes
Community Structure
- A community is a group of populations of different species living in a specific area.
- Communities are dynamic, which means their structure changes over time.
- Communities are characterized by patterns of species abundance and interactions between species
Disturbance and Succession
- Disturbance is any event that disrupts a community's structure, resources, or physical environment.
- Succession is the predictable change in community composition through time following a disturbance.
Stages of Succession
- Succession is characterized by different stages where species with different life history traits dominate.
- Early successional species are typically r-selected, meaning they have high growth rates, produce many offspring, and are short-lived.
- Mid and late successional species are typically K-selected, meaning they have slower growth rates, produce fewer offspring, and are longer-lived.
Conceptual Models of Succession
- Three models aim to explain the mechanisms driving successional changes: facilitation, inhibition, and tolerance.
- All models assume autogenic succession, meaning changes are driven by the community itself.
Facilitation Model
- The facilitation model is applicable primarily to primary succession, where a barren environment is colonized.
- Early colonizers modify the environment, making it suitable for later species.
Secondary Succession
- Secondary succession occurs after a non-catastrophic disturbance.
- Facilitation may not be the primary driver in secondary succession.
Inhibition Model
- The inhibition model applies mainly to secondary succession.
- Early colonists inhibit the growth of later arriving species.
- Succession progresses as early species die off and create opportunities for others to establish.
Tolerance Model
- The tolerance model also applies primarily to secondary succession.
- Late arriving species are tolerant of early arriving species.
- Late successional species outcompete others over time.
Late Succession Community
- In the absence of disturbance, succession progresses to a stable endpoint known as the climax community
- Climax communities can be disrupted by allogenic succession, where external factors drive changes.
- Communities are seldom in equilibrium
Disturbance Regime
- Disturbance regimes are characterized by their timing, magnitude, frequency, and predictability.
- Disturbed environments often have higher diversity due to habitat heterogeneity.
Intermediate Disturbance Hypothesis
- The hypothesis proposes that species diversity is highest at intermediate levels of disturbance.
Aquatic Succession
- In aquatic environments, succession can be observed in ponds and lakes as they transition towards terrestrial ecosystems.
Marine Succession
- In marine environments, succession unfolds on rocky shores, coral reefs, and other habitats
Food Chain and Indirect Effects
- Food chains represent energy transfer between trophic levels.
Trophic Levels
- Trophic levels represent the different positions within the food chain.
- The interactions between trophic levels influence community structure and stability.
Indirect Interactions
- Indirect interactions, such as trophic cascades, behavioral cascades, and ecosystem engineers, can significantly influence the dynamics of communities.
Trophic Cascades
- Trophic cascades occur when a predator at the top of the food chain influences populations at lower trophic levels.
- This is referred to as "top-down control"
Behavioral Cascade
- Predators can alter the behavior of prey, indirectly influencing lower trophic levels.
- This can be seen through the "ecology of fear" where prey adjust their foraging behavior due to predation risk.
Ecosystem Engineers
- Ecosystem engineers modify habitat and resource availability for other species.
- Engineers can be allogenic, modifying the environment through external means, or autogenic, modifying the environment through their own actions.
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Description
This quiz covers the concepts of community structure, disturbances, and ecological succession. Explore stages of succession and the characteristics of r-selected and K-selected species. Test your understanding of the dynamic nature of ecological communities.
