Community Ecology

Community Ecology - Physical appearance distinguishes...

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Physical appearance distinguishes biological communities and includes: o Relative sizes o Stratification o Distribution of the populations/species Large ecosystems consist of a mosaic of different-sized vegetation patches that change in response to changing conditions Life is patchy due to great variations in: o Physical conditions o Resources o Inhabiting species Edge – where on community transforms into another type of community Increasing edge causes: o Species to be more vulnerable to stresses (like predators and fires) o Creation of barriers that prevent species from: colonizing new areas finding food finding mates Biological communities shaped by: o Species diversity Species richness – number of different species Species evenness – the abundance of individuals within each of those species o Niche structure: How many ecological niches occur How they resemble or differ from one another How the species of different niches interact o Geographical location: Species diversity high in tropics, low at poles Constant daily climate and reliable food sources high species diversity Tropical species: o Specialized o Narrow niches o Live in microhabitats High latitudes where weather is cold and variable low species diversity High latitude species: o Not-specialized o Wide niches o Thrive in many environments and large expanses of land Species-rich environments:
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o Large number of species (high species richness) and only a few members of each species (low species evenness) Tropical rain forests Coral reefs Deep sea Large tropical lakes Types of species Native species: the species that normally live in a particular community Non-native species (invasive or alien species): other species that migrate into or are deliberately or accidentally introduced into a community o Can reduce a community’s native species and cause unintended consequences Indicator species: species that serve as early warnings of damage to a community o Examples: Trout – indicate water quality because they need clean water and lots of oxygen Birds – affected quickly by environmental changes Indicate loss or fragmentation of habitat and presence of pesticides Butterflies – associated with plants Indicate loss of these plants Canaries – coal miners used them to indicate poisonous gases Disappearing Amphibians (frogs, toads, and salamanders) Frogs – vulnerable to environmental disruption at various points of life cycle 33% of all amphibian species are threatened with extinction 43% of populations within the species are declining 80% of Caribbean’s amphibian species are threatened by severe habitat loss and disease Factors affecting frogs and other amphibians: o Habitat loss (draining and filling of wetlands< deforestation< and development) o Prolonged drought (dries up breed pools where tadpoles grow) o Pollution (exposure to pesticides
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Community Ecology - Physical appearance distinguishes...

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