Ch 25 notes - Ch 25- Evolutionary Processes Population- a...

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Ch 25- Evolutionary Processes Population - a group of individuals from the same species that live in the same area and regularly interbreed Four mechanisms that shift allele frequencies in populations: 1. Natural selection increases the frequency of certain alleles (survival and reproduction) 2. *#Genetic drift causes allele frequencies to change randomly (decrease/increase fitness) 3. *Gene flow - individuals leave one population, join another, and breed (introduce alleles to new population and remove alleles from old population) 4. *#Mutation modifies allele frequencies by continually introducing new alleles (beneficial/ detrimental/ no effect on fitness) *Do not favor certain alleles over others #introduce a nonadaptive component into evolution Hardy and Weinberg- all of the gametes produced in each generation go into a single group called the gene pool and then combine at random to form offspring - to determine which genotypes would be present in the next generation and in what frequency, simply calculate what happened when two gametes were plucked at random out of the gene pool many times and combined to form offspring p+q =1 P^2 + 2pq + q^2 = 1 Hardy-Weinberg principle - (1) If the frequencies of alleles A1 and A2 in a population are given by p and q, then the frequencies of genotypes A1A1, A1A2, and A2A2 will be given by P^2, 2pq, and q^2 for generation after generation. (2) When alleles are transmitted according to the rules of Mendelian inheritance, their frequencies do not
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Ch 25 notes - Ch 25- Evolutionary Processes Population- a...

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