4 - BIO 94 NOTES (1/12/09) Evolutionary processes Four...

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BIO 94 NOTES (1/12/09) Evolutionary processes Four components of Darwin’s theory of evolution by natural selection o Steady change of world o Change is gradual (gradualism) o Common descent o Natural selection o Multiplication of species Process of natural selection o Individuals in a population vary in many traits o Variation is in part heritable o Most successful in a given environment are more likely to survive and reproduce o Most successful are those with favorable variations, so favorable genes will increase in frequency Evolution is defined more specifically as a change in allele frequencies in a population over time Darwinian fitness is the ability of an ability of an individual to produce offspring, relative to that ability in other individuals in the population Evolution by natural selection is not goal directed . It simply favors individuals that happen to be better adapted to the environment at the time. Adaptations do not occur because organism want or need them. In general, selfish alleles will increase in frequency while self-sacrificing alleles decrease frequency Adaptation is: o A heritable trait o Phenotypic attribute o Dependent on environmental context Four mechanisms that cause evolution o Natural selection – increases the frequency of certain alleles o Genetic drift
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This note was uploaded on 11/16/2009 for the course BIOL BIOL taught by Professor Johnson during the Spring '08 term at Aberystwyth University.

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4 - BIO 94 NOTES (1/12/09) Evolutionary processes Four...

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