BIOL 211 Lecture Notes - Lecture 11: Gamete, Species Complex, Reproductive Isolation
Document Summary
Mechanisms of evolution: natural selection (from last time) Natural selection differential survival and reproduction of individuals in a population based on heritable variation in their phenotypes. Phenotype: observable properties of an individual (structure, color, behavior etc. : determined partially by genotype and partially by environment. If there is heritable variation in phenotype and that variation affects the survival and reproduction of individuals, then there will be changes in allele frequency. Suicide in lemmings is not an adaptation; a non-suicidal phenotype would immediatlely increase in frequency, and the non-suicidal allele would be strongly selected for. Natural selection does not favor traits that are good for the population or the species. Same with some pipefishes: sexual selection is different from normal natural selection because it may have affects counter to that of normal natural selection, which tends to favor traits that increase survival.