BIO 200 Lecture Notes - Lecture 31: Major Force, Charismatic Megafauna, Insular Biogeography
16 Dec 2016
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43 species -> 100 years -> huge diverse population. Wilson: species number defined by two forces: immigration and extinction. Extinction decreases species number: immigration and extinction. Immigration rates decrease over time: once certain number of species is reached number of new indivduals is limited, extinction rates increase over time. More population more resources have to be divided and competitive exclusion occurs: when graphed, there is an equilibrium point s* , at s* immigration and extinction balance each other. At that point species number should remain constant. Immigration and extinction still occurs: species # remains the same but the species present changes, curves are useful in a relative way, allow to make prediction about specific islands, size of island factor, less vulnerable to extinction. Lower extinctiion rate: low extinction rate increases s* position on graph. Larger island can support higher species number than a smaller one: major force that effects immigration is isolation.
