week 5

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Questions and Answers

What feature characterizes a stable ecological system?

High variability in states

Consistently changing states

Low variability in states (correct)

Unpredictable environmental conditions

What is the role of negative feedback loops in an ecosystem?

To keep the system within a finite range of states (correct)

To cause catastrophic failures in populations

To eliminate all predator species

To maintain constant change within the system

What occurs when there is not enough food to sustain predators?

Predator population decreases (correct)

Predators flourish while prey does not

Both populations remain stable

Prey increases uncontrollably

What does a resilient system have the capacity to do?

Withstand stress without collapsing Signup and view all the answers

Which of the following best describes a stability domain?

The range of system states that support ecological stability Signup and view all the answers

What happens to the predator population if extra cold winters lead to fewer bunny babies surviving?

The predator population decreases Signup and view all the answers

Which statement reflects an ecological consequence of increased prey population?

More food for predators will result in population growth Signup and view all the answers

What can destabilize an ecological system?

Excessive introduction of new species Signup and view all the answers

What is the definition of a keystone species?

An organism that helps to define an entire ecosystem. Signup and view all the answers

Which relationship type describes the interaction between a hummingbird and a flower?

Mutualism Signup and view all the answers

Which of the following statements about the competitive exclusion principle is true?

It can be violated by invasive species. Signup and view all the answers

What type of interaction occurs between a clownfish and a sea anemone?

Commensalism Signup and view all the answers

What defines the ability of an ecosystem to maintain balance after stress?

Resilience Signup and view all the answers

Which of the following is considered a parasitic relationship?

Mosquito and mammal Signup and view all the answers

What is a potential effect of invasive species on native ecosystems?

Enhance competition for resources Signup and view all the answers

In a complex adaptive system, what can cause a sudden switch to an alternate stability domain?

Excessive stress Signup and view all the answers

Which definition accurately describes symbiosis?

Interaction between species that influences their evolution. Signup and view all the answers

What is an example of stability domain switching involving sea otters?

Urchins thriving without predators Signup and view all the answers

What interaction can a trophic cascade have on food chains?

Influences entire food chain dynamics Signup and view all the answers

Which of the following is an example of mutualism?

Bee and flower Signup and view all the answers

Which scenario illustrates a top-down trophic cascade?

Removal of sea otters caused an explosion in urchin populations. Signup and view all the answers

What happens to a kelp forest when its sea otter population decreases significantly?

The forest becomes an urchin barren. Signup and view all the answers

What is the primary role of soil biota in ecosystem stability?

Providing nutrient cycling Signup and view all the answers

What typically triggers a switch to a new stability domain?

Major environmental changes or stress Signup and view all the answers

What causes a complex adaptive system to switch to a new stability domain?

Too much stress Signup and view all the answers

What is primarily responsible for determining species composition in a community?

Habitat and niche interactions Signup and view all the answers

What characterizes a climax community?

Stability in species composition Signup and view all the answers

Which of the following is NOT a feature of complex adaptive systems?

Isolation Signup and view all the answers

In terms of energy flow within an ecosystem, what is a food chain?

A linear path showing nutrient transfer Signup and view all the answers

Which type of species plays the role of a primary producer in an ecosystem?

Autotroph Signup and view all the answers

What is the term for the physical location where an organism lives out its life?

Habitat Signup and view all the answers

What best describes the concept of ecological succession?

Gradual change in species composition over time Signup and view all the answers

Study Notes

Course Information

Course name: SC253: Ecology and Environmental Problems
Date: September 30, 2024
Instructor: Prof. Amy L. Frick

Housekeeping

Midterm: October 14, 2024. The midterm will cover multiple choice and short answer questions from class discussions (September 16 - October 7), readings referenced in class, and in-class activities/assignments.
Ecological Footprint Essay: Deadline extended to October 21, 2024. Find updated details in the (/Content/Case Study of One) folder.
Reading assignments: Check the updated (/Course information/schedule) folder for reading assignments for the following week.

Ecosystem Organization

Ecosystems are organized in a hierarchical structure: Organism → Population → Community → Ecosystem → Biome
Shows the relationships between living things and their environment.

Ecological Stability

A stable ecosystem has a low variability, resisting shifts in environmental conditions. Stability is maintained by negative feedback loops.
Action → Effect → Action (negative feedback loop)

Stability Domain

Stability domain: the range within which a system, or group of organisms, can withstand stress before collapsing to a new stability domain.
Environmental stress can push a system from one stability domain to another.

Resilience

Resilience: an ecosystem's ability to maintain balance after stress.
Factors influencing resilience include compensatory dynamics, plant diversity, temporal mean of ANPP, soil mutualists/high soil biodiversity, and free-living soil biota.

Stability Domain Shift

As ecosystems are pushed beyond their stability domain, they can shift to a new one.
Feedback loops can either reinforce the shift or bring the system back to its original state.

"Switch"

Complex adaptive systems can remain relatively stable over long periods.
However, high levels of stress can lead to sudden changes in stability domain.

Example of Stability Domain Switching: Sea Otters and Kelp

The disruption of an ecosystem, like the removal of predators (otters), can result in major changes: Maintenance → Crisis → Dissolution → Reorganization

Trophic Cascade

A trophic cascade is a significant indirect interaction within an ecosystem, affecting the entire food chain.
Removal of sea otters can lead to increases in sea urchin populations, resulting in the decimation of kelp forest communities.

Stability Domain Switching (Example: Marine Forests and Sea Urchins)

Climate change impacts and overfishing are examples of factors that can cause stability domain switching.

Complex Adaptive Systems

Developed through community assembly.
Exist in stability domains.
High stress can cause a "switch" to a new stability domain.

Ecological Succession

A process of progressive change in community structure over time, often leading to a climax community.
Bare rock → Lichens → Small annual plants/lichens → Grasses and perennials → Grasses, shrubs, and shade-intolerant trees → Shade-tolerant trees.

What Makes a Community Stable?

Species diversity is a key factor. This includes both species richness (number of species) and species composition (identity of species).
High biodiversity vs. Low biodiversity
A diverse community is often more stable than a less diverse one.

Ecological Niches

Autotrophs (producers), heterotrophs (consumers), and decomposers play distinct roles within ecosystems.
Defining roles within the food web.

Trophic Levels

Organisms within an ecosystem can be categorized into trophic levels.
Plant → Herbivore → Carnivore → Apex predator (primary producer - primary consumer - secondary consumer - tertiary consumer)

Ecosystem = Flow of Energy

An ecosystem's structure is defined by the flow of nutrients and energy through its communities.
Communities and organisms in an ecosystem form a food web.

Food Web

Represents the complex interconnected paths of energy and nutrients within an ecosystem.
A food web differs from a food chain because it represents all possible connections in the overall ecosystem. Multiple food chains are interconnected within a food web.

Vocabulary

Urchin
Sea otter
Kelp
Killer Whale

Keystone Species

Keystone species have crucial roles in an ecosystem.
Their removal or disruption can cause significant changes in the overall community structure.
Sea otters are an example.

Relationships Between Species

Relationships between species in ecosystems, including:
- Competitive relationships
- Predator-prey relationships
- Symbiotic relationships:
  - Mutualism
  - Commensalism
  - Parasitism

Competition

Competition (at any trophic level) occurs when species compete for resources such as food, water, and habitat.
Competitive exclusion: two species competing for the same resources cannot coexist.

Invasive Species

Invasive species may outcompete native species for resources

Group Activity

Students will research and present on specific examples of interrelationships between species. Examples include Aphids/ants, Oxpeckers/mammals; e.coli in rodents; mycorrhizae/vascular plants and allelopathy in plants

Additional Details

The midterm date is October 14, 2024, covering material from September 16-October 7, including class discussions, readings, and in-class activities/assignments.
The deadline for the Ecological Footprint Essay is October 21, 2024 and further details can be found in the designated folder.
Students are expected to have researched the subject matter, and present their findings with a diagram that explains their findings.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Prepare for the SC253 midterm exam with this quiz that covers the foundational concepts of ecosystem organization and ecological stability. Review key terms and relationships among organisms, populations, communities, ecosystems, and biomes. It's essential for understanding ecological interactions and environmental issues.