BIO205H5 Lecture Notes - Lecture 19: Krakatoa, Eastern Gray Squirrel, Keystone Species

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5 Feb 2015

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Lecture 19: how do communities change over time: not all species have the same impact, for example sea otters feed on sea urchins, and as a result kelp forests develop. In areas of fertilized grass, grass aphids increase while nettle aphids decrease. This increase in grass aphids attracts lady bugs which are a predator, which feed on both types of aphids. New species came onto the island: succession is marked by a sequence, sere: sequence of communities on a given site, seral stage: changes from one community to the next. Each stage is defined by a distinct community: ex: succession in hudson bay. After every disturbance, all species start growing again. In areas of mere disturbances, there is less diversity and smaller populations due to lack of time. In areas of fewer disturbances, there is more diversity and larger population sizes because there is more time.