EvolutionMechanisms160-page7

EvolutionMechanisms160-page7 - in populations....

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Evolutionary Mechanisms - 7 5 . Natural Selection (and selection, in general) In the Hardy-Weinberg equilibrium, all individuals must be equally adaptive in their environment for all of their genetic characteristics. In real populations this is not the case. The many variants within a population will have different responses to the common environment in which they live. The conditions of the environment enhance the survival of certain phenotypes so these individuals are likely to have greater reproductive success than individuals whose survival is compromised. This differential reproduction results in passing more of the successful genes into the gene pool affecting the gene frequency of the next generation Natural selection is the result of this differential reproduction. Evolution by natural selection occurs whenever these conditions are met
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Unformatted text preview: in populations. Documentation of this abounds in the field of ecology where studies of competition are common. Although natural selection acts on phenotypes, recall that the phenotype is the expression of the genotype, and it is the specific alleles that are passed on to the next generation. Natural selection does not cause genetic changes within an individual. An individual cannot evolve. Natural selection acts on the individual. The population evolves as a consequence of differential reproduction. Moreover, evolutionary change is not, in and of itself, something that is good or more valuable (or bad). Evolutionary change occurs because a specific environmental condition favors one genetic combination over another. If the environment changes, the genetic combination favored may also change....
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