BIOL 1202 Chapter : Chapter 23
Document Summary
The smallest unit of evolution: evolutionary processes act on individuals, but populations evolve. In sexually reproducing organisms, sexual recombination produces most of the variability in each generation. Variation within a population: discrete characters: classified on an either-or basis, ex- flower color in pea plants, quantitative characteristics: vary along a continuum within a population, ex- height, weight. Allele and genotype frequencies: allele frequencies, p= frequency of allele 1, q= frequency of allele 2, genotype frequencies, p2= frequency of homozygous dominant, q2= frequency of homozygous recessive, 2pq= frequency of heterozygous, p2+2pq+q2=1. Natural selection is the only mechanism that consistently causes adaptive evolution: natural selection- differential success in the reproduction of different phenotypes resulting from their interactions with the environment. Sexual selection: type of selection that favors a trait, giving an individual a competitive edge in attracting or keeping a mate. Intrasexual selection- direct competition among individuals of one sex for mates of the opposite sex.
