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Community Structure quiz #1

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  • What are the four key attributes of community structure, and how do they contribute to biodiversity and ecosystem resilience?
    The four key attributes of community structure are species richness (the number of different species), relative abundance (the proportion of each species), species interactions (such as competition, mutualism, and predation), and physical attributes (biotic and abiotic factors, including species distribution). Together, these factors determine biodiversity and influence ecosystem resilience, with higher species diversity generally leading to greater stability and resistance to disturbances.
  • What is species richness in the context of community structure?
    Species richness refers to the total number of different species present in a community.
  • How does relative abundance differ from species richness?
    Relative abundance is the proportion of each species in relation to all individuals in the community, while species richness is just the count of different species.
  • What does a higher Shannon Diversity Index value indicate about a community?
    A higher Shannon Diversity Index value indicates greater species diversity and a more biodiverse community.
  • How does higher species diversity affect community stability and resilience?
    Higher species diversity generally leads to greater stability and resistance to disturbances, making communities more resilient and able to recover quickly.
  • What is trophic structure and how is it represented?
    Trophic structure refers to the feeding relationships between organisms in a community and is represented by food chains and food webs.
  • Why are food chains typically short in nature?
    Food chains are short because energy transfer between trophic levels is very inefficient, with only about 10% of energy passing to the next level.
  • What is the difference between a foundation species and a keystone species?
    A foundation species has a large biomass and strong community-wide effects, while a keystone species has low abundance but a disproportionately large ecological impact.
  • How do ecosystem engineers influence their communities?
    Ecosystem engineers significantly alter their physical environment, creating new habitats and affecting other species, such as beavers building dams.
  • What is the difference between bottom-up and top-down control in community structure?
    Bottom-up control is driven by resource or food availability at lower trophic levels, while top-down control is influenced by organisms at higher trophic levels, such as predators.
  • What is the effect of keystone species on an ecosystem?
    Keystone species have a disproportionately large impact on their ecosystem relative to their low abundance or biomass. They play critical ecological roles, such as pollination or predation, that help maintain the structure and stability of the community. The loss of a keystone species can lead to significant changes in community composition and ecosystem function.