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Community Ecology. A thing is right when it tends to preserve the integrity, stability, and beauty of the biotic community. It is wrong when it tends otherwise. Aldo Leopold, 1949.
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Community Ecology A thing is right when it tends to preserve the integrity, stability, and beauty of the biotic community. It is wrong when it tends otherwise. Aldo Leopold, 1949
Species must ultimately exist within functional communities and ecosystems interacting with their biotic and abiotic environment
Critical Species Interactions • Not all species in a community are equally important to the structure and function of a community.
Keystone species are especially important to community dynamics. keystone predators- keep densities of dominant species low that in the absence of predation would exclude other species keystone food source- keystone habitat modifier- e.g. beaver, prairie dog mutualistic relationships- two or more species benefit from an interaction e.g. mycorrhizal fungi- indirect effects- e.g. Stoneroller, Campostoma control algae in pools without Bass Micropterus in Oklahoma streams
Disturbance Regimes • equilibrium -vs- dynamic • succession- gradual replacement of community types • sere • climax community • disturbances influence probabilities of extinction and colonization and thus effect biodiversity
Invasive Species The effects of invasive species depends on the species and communities involved. The majority of introductions fail. Which species introductions succeed? Which species are most likely to become extinct as a result of introductions? rare species species with highly variable populations
Characteristics of Invasive Species • High reproductive rate • Pioneer species • Short generation time • High dispersal rates • Single-parent reproduction (gravid females can colonize) • Vegetative or clonal reproduction • Phenotypically plastic • Broad native range • Habitat generalist • Polyphagous • Human commensal
Characteristics of Invadable Communities • Climatically similar to habitat of invader • Early successional • Low diversity of native species • Absence of predators on invading species • Absence of fire in evolutionary history • Anthropogenically disturbed
Some Example Introductions Gambusia, Mosquito Fish Felisdomesticus rats & mice goats Zebra Mussels Fire Ants Kudzu