Community Ecology notes - Chapter7:CommunityEcology...

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Chapter 7: Community Ecology Community Structure and Species Diversity Community Structure: Appearance Matters Biological communities differ in their structure and physical appearance. Species Diversity and Niche Structure: Different Species Playing Different Roles Biological communities differ in the types and numbers of species they contain and the ecological roles those species play. Species diversity The number of different species it contains (species richness) combined with the abundance of individuals within each of those species (species evenness) Community characteristics Niche structure How many potential ecological niches occur, how they resemble or differ from one another, and how the species occupying different niches interact. Geographical location Types of Species Types of Species in Communities Native, nonnative, indicator, keystone, and foundation species play different ecological roles in communities. Native species Species that normally live and thrive in a particular community Nonnative species, invasive species, or alien species Species that migrate into or are deliberately or accidentally introduced into a community Indicator Species: Biological Smoke Alarms Some species can alert us to harmful environmental changes taking place in biological communities. Indicator species Species that serve as early warnings of damage to a community or an ecosystem Case Study: Why Are Amphibians Vanishing? Disappearing amphibian species may indicate a decline in environmental quality in many parts of the world. Amphibians Factors that can affect amphibians: Habitat loss and fragmentation Prolonged drought Pollution Increases in ultraviolet radiation Parasites Viral and fungal diseases Climate change Overhunting
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Natural immigration or deliberate introduction of nonnative predators and competitors Why should we care if some amphibian species become extinct? This trend suggests that environmental health is deteriorating in parts of the world because amphibians are sensitive biological indicators of changes in environmental conditions such as habitat loss and degradation, air and water pollution, UV exposure, and climate change. Adult amphibians play important ecological roles in biological communities. Ex. Amphibians eat more insects than do birds. Extinction of amphibians could lead to multiple extinctions of species. Amphibians are a genetic storehouse of pharmaceutical products waiting to be discovered. Compounds in secretions from amphibian skin have been isolated and used as painkillers and antibiotics and as treatment for burns and heart disease Keystone Species: Major Players Keystone species help determine the types and numbers of other species in a community.
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