Chapter 25 - Chapter 25 Evolutionary Processes Natural...

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Chapter 25: Evolutionary Processes Natural selection Genetic Drift Gene flow Mutation Gene pool Hardy- Weinberg principle H-W serves as a null hypothesis Genetic variation Directional selection Stabilizing selection Disruptive selection Genetic drift Population- a group of individuals from the same species that live in the same area and regularly interbreed Natural selection works on individuals, change occurs in populations by increasing the frequency of alleles Causes the allele frequency to change randomly. Drift may in some cases cause alleles htat decrease fitness to increase in frequency Occurs when individuals leave one population, join another, and breed, allele frequencies may change when gene flow occurs Modifies allele frequencies by continually introducing new alleles. May be beneficial or detrimental or have no effect on fitness Natural selection is not the only agent responsible for evolution All the gametes produced in each generation go into the gene pool and tehn combine at random to form offspring p + q = 1 p 2 + 2pq + q 2 = 1 When alleles are transmitted via meiosis and random combination of gametes, their frequencies do not change over time. For evolution to occur, some other factor must come into play No natural selection at the gene in question No genetic drift, or random allele frequency changes, affecting the gene in question No gene flow No mutation Random mating with respect ot gene in question If one of the above is at work, then yes, the H-W will be the null hypothesis because the H-W principle is used to test the hypothesis that currently no evolution is occurring at a particular gene and that in the previous generation, mating was random with respect to the gene in question Heterozygous individuals may have higher fitness The number and relative frequency of alleles that are present in a particular population.
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Chapter 25 - Chapter 25 Evolutionary Processes Natural...

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