Natural_selection bolker

Natural_selection bolker - forms of selection directional:...

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1 forms of selection • directional: faster, stronger, larger … (vs. biochemical or physiological constraints ) stabilizing: optimum trait matches environment • Diversifying (disruptive): multiple strategies or complex environment effects of selection • may change mean trait value • changes (usually decreases) trait variance directional incr. mean, decr. variance diversifying constant mean, incr. variance stabilizing constant mean, decr. variance • effect on mean = heritability times strength of selection what maintains heritable variation in populations? Genetic variation • expect little variation (low heritability) in natural populations, especially fitness-related traits reduce variation – Mutation is rare • but protein polymorphisms ( allozymes ) show high levels of variation neutral theory of evolution : many alleles are selectively neutral • doesn’t explain variation in fitness-related traits …
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This note was uploaded on 04/24/2008 for the course BSC 2010 taught by Professor Bowes during the Spring '08 term at University of Florida.

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Natural_selection bolker - forms of selection directional:...

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