Community Ecology: Ecosystem Implications
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Questions and Answers

What does alpha (α) diversity measure?

  • Diversity between communities
  • Diversity within a community (correct)
  • Diversity across multiple regions
  • None of the above

    • Beta (β) diversity measures diversity across multiple regions.

    False

    What is the equation for calculating gamma (γ) diversity?

    γ = α + β

    Beta (β) diversity is usually a measure of __________.

    <p>dissimilarity</p> Signup and view all the answers

    Match the type of diversity with its definition:

    <p>Alpha (α) = Diversity within a community Beta (β) = Diversity between communities Gamma (γ) = Diversity across multiple regions Diversity-stability debate = The relationship between diversity and ecosystem stability</p> Signup and view all the answers

    Which community is expected to have higher functional diversity with equal species richness?

    <p>Both communities are equal</p> Signup and view all the answers

    Gamma (γ) diversity is the diversity found within a single region.

    <p>False</p> Signup and view all the answers

    List two components considered when evaluating community structure.

    <p>Species richness, evenness</p> Signup and view all the answers

    What does species richness refer to in an ecological community?

    <p>The total number of different species present</p> Signup and view all the answers

    Keystone species have a disproportionately large impact on their environment compared to their abundance.

    <p>True</p> Signup and view all the answers

    Name one example of a keystone species mentioned in the content.

    <p>Purple starfish (Pisaster)</p> Signup and view all the answers

    The introduction of the N-fixing tree, Morella faya, in Hawaii led to an increase in ______ availability.

    <p>nitrogen</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>Alpha diversity = Species diversity within a particular area or ecosystem Beta diversity = Comparison of diversity between ecosystems Gamma diversity = Overall diversity across a large geographic area Ecosystem engineers = Species that create or modify habitats</p> Signup and view all the answers

    Which of the following is a consequence of declining biodiversity?

    <p>Higher rates of invasive species dominance</p> Signup and view all the answers

    Changes in species composition can impact ecosystem processes.

    <p>True</p> Signup and view all the answers

    What term describes the debate regarding the relationship between diversity and ecosystem stability?

    <p>Diversity-stability debate</p> Signup and view all the answers

    Which of the following species is classified as a keystone species?

    <p>Predators</p> Signup and view all the answers

    All species in a community contribute equally to ecological diversity.

    <p>False</p> Signup and view all the answers

    What term is used to describe species that maintain or create new habitats?

    <p>Ecosystem engineers</p> Signup and view all the answers

    Dominant species are defined as the most __________ in a community.

    <p>abundant</p> Signup and view all the answers

    Which type of plants are known to fix nitrogen in the soil?

    <p>N-fixing plants</p> Signup and view all the answers

    Invasive species have the same ecological impact as native species.

    <p>False</p> Signup and view all the answers

    What is the primary focus of the diversity-stability debate?

    <p>The relationship between diversity and ecosystem stability.</p> Signup and view all the answers

    What is a community in ecological terms?

    <p>A group of interacting species in a defined geographic area.</p> Signup and view all the answers

    Species richness only refers to the number of individuals of each species in a community.

    <p>False</p> Signup and view all the answers

    What are the three components of species diversity?

    <p>Species richness, evenness, and relative abundance.</p> Signup and view all the answers

    Biodiversity encompasses species diversity, functional group diversity, and ________ diversity.

    <p>habitat</p> Signup and view all the answers

    Which habitat has higher species diversity?

    <p>Habitat 2 with 6 species; one with 15 individuals and five with 1 each.</p> Signup and view all the answers

    Match the term with its correct description:

    <p>Species richness = Number of different species in a community Evenness = How populations of different species relate in abundance Keystone species = Species that play a critical role in maintaining the structure of an ecosystem Ecosystem engineers = Organisms that create, significantly modify, maintain or destroy habitats</p> Signup and view all the answers

    Keystone species have minimal impact on their ecological community.

    <p>False</p> Signup and view all the answers

    Relative abundance describes how ______ or ______ a species is in relation to others in a community.

    <p>common, rare</p> Signup and view all the answers

    Which type of tree foliage is generally less flammable?

    <p>Deciduous tree foliage</p> Signup and view all the answers

    Invasive European beach grass decreases streambank erosion.

    <p>False</p> Signup and view all the answers

    What ecological phenomenon does the diversity-stability hypothesis address?

    <p>The relationship between community diversity and ecosystem stability.</p> Signup and view all the answers

    Invasive Tamarix alters flooding regimes by __________ waterways.

    <p>desiccating</p> Signup and view all the answers

    Match the invasive species with their impact:

    <p>Tamarix = Desiccates waterways Black wattle = Increases streambank erosion European beach grass = Alters dune formation Deciduous trees = Less flammable foliage</p> Signup and view all the answers

    Which of the following hypotheses is associated with Charles Elton's work?

    <p>Diversity-stability hypothesis</p> Signup and view all the answers

    Species composition can only alter fire disturbance regimes.

    <p>False</p> Signup and view all the answers

    Name one factor that contributes to the diversity-stability hypothesis.

    <p>Community complexity or species richness.</p> Signup and view all the answers

    Which species has the highest relative abundance in the example provided?

    <p>Yellow poplar</p> Signup and view all the answers

    The Shannon-Wiener Index (H') measures only species richness.

    <p>False</p> Signup and view all the answers

    What is the total number of species in the provided data?

    <p>10</p> Signup and view all the answers

    The highest value of the Shannon-Wiener Index (Hmax) occurs when all species are present in __________ abundance.

    <p>equal</p> Signup and view all the answers

    Match the following species to their respective relative abundance:

    <p>Yellow poplar = 0.45 Sassafras = 0.39 Black cherry = 0.044 Cucumber magnolia = 0.04</p> Signup and view all the answers

    Which index is used as a measure of species diversity?

    <p>Shannon-Wiener Index (H’)</p> Signup and view all the answers

    Species evenness refers to how many different species are present in an ecosystem.

    <p>False</p> Signup and view all the answers

    How many total trees are present in Habitat 1?

    <p>20</p> Signup and view all the answers

    The empirical measure of species diversity combines species __________ and ______________.

    <p>richness, evenness</p> Signup and view all the answers

    What is the formula used to calculate the product for the Shannon-Wiener Index?

    <p>Σ(pi x ln(pi))</p> Signup and view all the answers

    Study Notes

    Community Ecology: Implications for Ecosystems

    • Community ecology studies interacting species within a defined geographic area.
    • Community boundaries can be unclear, encompassing geographic extent and interaction extent.
    • Taxonomic or functional species groups make up communities. Examples include boreal communities (plants, animals, fungi) in terrestrial and aquatic habitats.
    • Other community examples include plant communities, bird communities, and aquatic communities.

    Measuring Community Attributes

    • Trophic Structure: Examining feeding relationships (previous lecture).
    • Species Richness, Evenness, & Diversity: Quantifying the number of species present, and their relative abundance (today's lecture).
    • Species Composition & Functional Groups: Detailed species inventory and grouping species based on similar ecological roles.

    Species Diversity

    • Species diversity combines species richness and evenness.
    • Richness: the number of species in a community (S).
    • Evenness (or relative abundance): measures how evenly distributed species are in a community.
    • A comprehensive measure incorporates both the number of species and their relative abundance.

    Measuring Species Diversity

    • Shannon-Weiner Index (H') is an integrative index.
    • H' combines all species relative abundances with ln (natural logarithm) to create a standardized measure of species diversity. The formula is: H' = -∑(pᵢ × ln pᵢ).
    • This index is bounded between 0 and Hmax, where Hmax is calculated where all species are equally abundant (Hmax = ln S).

    Alpha, Beta, and Gamma Diversity

    • α-diversity: measures species diversity within a single community or site (local species pool).
    • β-diversity: measures species diversity between communities (within a region); a measure of dissimilarity.
    • γ-diversity: measures species diversity across multiple regions within a larger landscape (landscape species pool).

    Keystone Species and Ecosystem Engineers

    • Dominant species are the most abundant or have the largest biomass in a community.
    • Keystone species have a disproportionate impact on community structure relative to their abundance or biomass.
    • Ecosystem engineers create or maintain habitats for themselves and/or other species.

    Diversity-Stability Debate

    • The diversity-stability hypothesis suggests more diverse communities are more stable.
    • However, this relationship isn't consistently observed across all species interactions and ecosystems.

    Associated Readings/Videos

    • Textbook Chapter 11 (pages 322-335).
    • McCann KS (2000) The diversity-stability debate. Nature 405: 228-233. (PDF on Blackboard).

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    Related Documents

    BIOL 312 Lecture Slides Topic 11 PDF

    Description

    Explore the essential concepts of community ecology, focusing on the interactions between species in different ecosystems. This quiz will assess your understanding of trophic structures, species diversity, and the characteristics of various communities within defined geographic areas.

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