BIOL359 Chapter Notes - Chapter 9: Directional Selection, Disruptive Selection, Stabilizing Selection
24 Sep 2018
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Ed(cid:373)u(cid:374)d brodie"s study (cid:373)o(cid:374)itored the survival of several hu(cid:374)dred individually marked juvenile garter snakes. He estimated the effect on fitness of two traits that help the snakes evade predators: color pattern (striped vs. unstriped or spotted) and escape behaviour (straight-line escape vs. many reversals of direction) The snakes with the highest rates of survival were those with stripes that fled in a straight line, and those without stripes that performed many reversals of direction. Snakes with other combinations of traits were more easily spotted by predators and eaten. We can follow the evolution of a population by tracking the position of the average individual. 9. 6 modes of selection and the maintenance of genetic variation. The relationship between phenotype and fitness may be complex. A variety of patterns, or modes of selection are possible. All three modes of selection cull individuals with low fitness and preserve individuals with high fitness so, all three modes increase the mean fitness of the population.
