Exam #2-study aids_25

Learning Objectives

• Species Definition Concepts

  • Identify two main concepts used to define species.

  • Understand criteria utilized by each species concept to classify species.

  • Apply these species concepts to adequately define species.

• Speciation

  • Understand necessary steps for speciation to occur.

  • Comprehend mechanisms creating population isolation.

  • Learn how evolution mechanisms can influence divergence between populations.

  • Explain possible occurrence of sympatric speciation.

  • Recognize that evolution is not goal-oriented concerning speciation.

  • Understand consequences of secondary contact, including hybridization.

• Niche Concept

  • Define and visualize a niche.

  • Understand the competitive exclusion hypothesis and potential outcomes.

  • Identify factors limiting a species’ niche or range on Earth.

• Community and Ecosystem Interactions

  • Define a community.

  • Understand the Island-Equilibrium Model.

  • Learn about interspecific interactions within a community and their evolutionary consequences.

• Food Chain and Web

  • Understand concepts of food chains and food webs.

  • Identify influences a dominant and keystone species can have on the community.

  • Explain bottom-up and top-down control mechanisms.

• Population Dynamics

  • Understand mathematical models of population growth.

  • Recognize potential population growth patterns: growth, slight fluctuation, and cyclical fluctuation.

  • Explore the relationship between population density and birth/death rates.

  • Explain and interpret survivorship curves.

• Human Influence in Ecology

  • Understand the role of humans in the global community of life.

In-Class Lecture Answers

• Lecture 12:

  • 1. c

  • 2. c

  • 3. e

• Lecture 13:

  • 1. b

  • 2. c

  • 3. b

  • 4. b

• Lecture 14:

  • 1. c

  • 2. e

  • 3. a

  • 4. d

• Lecture 15:

  • 1. d

  • 2. c

  • 3. e

  • 4. c

• Lecture 16:

  • 1. d

  • 2. b

  • 3. c

  • 4. b

  • 5. a

• Lecture 17:

  • 1. e

  • 2. b

  • 3. c

Check Point Questions

• Suggested questions from Hillis Text:

  • Ch. 17: 17.1 (all), 17.3 (all), 17.4 (all)

  • Ch. 41: 41.2 (#1, 3), 41.3 (#1, 2), 41.5 (#1, 2)

  • Ch. 42: 42.1 (#1), 42.2 (#1,2), 42.4 (all)

  • Ch. 43: 43.1 (all), 43.2 (#2,3), 43.3 (#2,3)

  • Ch. 44: 44.2 (#2), 44.3 (#1), 44.4 (all)

  • Ch. 45: 45.4 (all)

Additional Questions

1. Reflection on breeding behavior in flying insect species across different islands and potential for speciation in 1000 years.

2. Discuss the misconception in "One species evolves into another species."

3. Explain the influence of a keystone species on community abundance versus a dominant species' influence.

Species Definition Concepts

• Species Concepts: Two main concepts to define species include the Biological Species Concept and the Morphological Species Concept.

• Criteria: The Biological Species Concept classifies species based on reproductive isolation, while the Morphological Species Concept relies on physical characteristics.

• Application: These concepts help in identifying and classifying different species accurately.

Speciation

• Necessary Steps: Speciation requires isolation of populations, whether through geographical barriers or reproductive isolation.

• Isolation Mechanisms: Mechanisms like allopatric and sympatric speciation lead to divergence by limiting gene flow.

• Evolution Influence: Evolution can lead to significant changes that separate populations over time.

• Sympatric Speciation: This occurs without physical barriers, often through behavioral or ecological differences.

• Evolution Goal: Evolution is not directed toward creating species but is a response to environmental pressures.

• Secondary Contact: When different species come into contact again, hybridization may occur, leading to diverse consequences.

Niche Concept

• Definition: A niche is the role or function of a species within its ecosystem, including its habitat and interactions.

• Competitive Exclusion Hypothesis: This theory states that two species competing for the same resources cannot coexist if other ecological factors are constant.

• Limiting Factors: Various biotic and abiotic factors can restrict a species’ niche or range on Earth.

Community and Ecosystem Interactions

• Community Definition: A community is composed of different species interacting within a shared environment.

• Island-Equilibrium Model: This model explains species diversity on islands, balancing immigration and extinction rates.

• Interspecific Interactions: The relationships between species, such as predation, competition, and mutualism, can drive evolution.

Food Chain and Web

• Food Chains: A linear representation of energy flow from producers to consumers.

• Food Webs: A complex network of feeding interactions among various organisms.

• Dominant vs. Keystone Species: Dominant species have a large impact on community structure, while keystone species play a critical role in maintaining ecological balance.

• Control Mechanisms: Bottom-up control (resource-driven) and top-down control (predator-driven) mechanisms regulate populations within ecosystems.

Population Dynamics

• Mathematical Models: Models that predict population growth patterns over time, including exponential and logistic growth.

• Growth Patterns: Populations may exhibit growth, slight fluctuation, or cyclical fluctuation depending on environmental factors.

• Density Relationships: The relationship between population density and birth/death rates can determine population stability.

• Survivorship Curves: Graphical representations that show the survival rates across different ages within a population.

Human Influence in Ecology

• Role in Ecosystems: Humans significantly impact ecosystems through activities that alter habitats, introduce invasive species, and contribute to climate change.

Species Definition Concepts

1. Species Concepts: The two main concepts to define species are the Morphological Species Concept and the Biological Species Concept.

2. Classification by the Biological Species Concept: This concept classifies species based on reproductive isolation, meaning that members of a species can breed with each other but not with members of other species.

3. Classification by the Morphological Species Concept: This concept classifies species based on their physical traits such as size, shape, and color.

Speciation

4. Necessary Steps for Speciation: Speciation requires either a physical barrier (like mountains or rivers) or reproductive differences, such as differences in mating seasons.

5. Isolation Mechanisms: Mechanisms like allopatric (geographically isolated) and sympatric (isolated without a physical barrier) speciation contribute to divergence by limiting gene flow.

6. Influence of Isolation on Evolution: When populations are separated by barriers, their evolution over time may lead to them no longer recognizing each other as the same species or being unable to reproduce together.

7. Sympatric Speciation: This occurs when there are behavioral or ecological differences that prevent populations from mating, even in the same physical space.

8. Nature of Evolution: Evolution is not a process aimed at creating new species; instead, it is a response to environmental factors and pressures.

9. Consequences of Secondary Contact: When different species come into contact again, hybridization may occur, potentially leading to new hybrid species or impacts on the existing species.

Niche Concept

10. Definition of Niche: A niche refers to the role or function of a species within its ecosystem, including its habitat, resource use, and interactions with other species.

11. Competitive Exclusion Principle: According to this principle, two species competing for the same limited resource cannot coexist in the same ecological niche.

12. Limiting Factors: The niche or range of a species can be restricted by various biotic factors (like competition or predation) or abiotic factors (like temperature, moisture, and nutrients).

Community and Ecosystem Interactions

13. Definition of Community: A community is composed of populations of different species interacting within a shared environment.

14. Island-Equilibrium Model: This model describes how species diversity on islands is balanced by immigration rates and extinction rates, leading to a dynamic equilibrium of species.

15. Interspecific Interactions: These are relationships between different species in a community, including competition, mutualism (beneficial for both), or predation.

Food Chain and Web

16. Food Chains vs. Food Webs: A food chain is a linear representation of energy flow between producers and consumers, while a food web is a complex network of feeding interactions among various organisms.

17. Dominant vs. Keystone Species: Dominant species have a large impact on the structure of a community, while keystone species play a critical role in maintaining ecological balance, even if they are not the most abundant.

18. Control Mechanisms: Bottom-up regulation refers to resource-driven processes where the abundance of lower trophic levels affects higher ones, while top-down regulation is driven by predation, where predators control the population of prey.

Population Dynamics

19. Mathematical Models: These include models that predict population growth patterns, such as exponential growth (unlimited resources) and logistic growth (limited resources).

20. Growth Patterns: Population growth may exhibit patterns such as steady growth, slight fluctuations, or cyclical dynamics, influenced by environmental factors.

21. Population Density and Stability: The relationship between population density and birth/death rates is crucial, as it impacts the overall stability of the population.

22. Survivorship Curves: These curves graphically represent the survival rates of individuals across different ages within a population, providing insights into life history and strategies.

Human Influence in Ecology

23. Human Impact on Ecosystems: Humans significantly affect habitats and ecosystems, including through habitat alteration and the introduction of invasive species.

24. Challenges for Species: Human activities often change environments in ways that can threaten the survival of species, making it difficult for them to thrive.

Dominant vs. Keystone Species

Dominant Species

• Definition: A dominant species is one that has a large impact on the structure of a community due to its abundance or biomass.

• Characteristics:

  • They typically make up a significant portion of the community's total biomass.

  • Their presence can greatly influence the community's composition and productivity.

• Examples: Common examples include certain tree species in forests (like oak or maple) or grasses in a prairie system—these species dominate community structure and can affect which other species thrive.

Keystone Species

• Definition: A keystone species is one that has a disproportionately large effect on its environment relative to its abundance. Removing a keystone species can significantly alter the structure and diversity of a community.

• Characteristics:

  • They play a critical role in maintaining the ecological balance within their community.

  • Their influence is often indirect, often through predator-prey relationships or other ecological interactions.

• Examples: Classic examples include sea otters, which help control sea urchin populations and thus maintain kelp forest ecosystems, or wolves in Yellowstone National Park, which regulate herbivore populations and promote healthy vegetation diversity.

Key Differences

• Impact Relative to Abundance: Dominant species are significant because of their high numbers, whereas keystone species are crucial due to their unique ecological role.

• Ecosystem Stability: The removal of a dominant species may change community structure but is less likely to result in a complete collapse of the ecosystem, while the removal of a keystone species often leads to dramatic shifts and loss of biodiversity.