LIFESCI 15 Lecture Notes - Lecture 4: Phenotype, Genetic Drift, Sexual Selection
Document Summary
An organism with greater reproductive success than other individuals in the population. Critical to assessing tness is understanding that it is measured: Take home message #1: fitness is the relative reproductive success of a phenotype or genotype. Alleles that confer the highest tness on the individuals carrying them will increase their market share in a population over time. 1. mutation: a direct alteration of dna so that one allele is changed to another. How can this occur? (i. e. sun, x-rays, power plants, chemicals in the air) 2. migration: within a population some individuals leave or new individuals arrive, thus changing the overall allele frequencies. 3. genetic drift: a random change in allele frequencies. How can this occur? (more common in smaller populations than bigger populations, blue eye brown eye example) Take home message #2: evolution can occur via one of four agents: mutation, migration, drift, natural selection. Sexual selection: often, there is con ict between reproduction and survival .
