1. Sexual Selection In order for random mating to occur, all members of the population must have equal opportunity to produce offspring. M any species select mates based on certain traits such as size, strength or coloration FEMALES do the choosing!

2. Large Population A population must be very large, so genetic drift doesn’t cause changes in allele frequency by random chance.

3. No Immigration or emigration When organisms move into (immigration) or out of (emigration) a population, they bring or take genes with them If enough organisms move, the gene pool will be adjusted If the gene pool is adjusted then it can not reach genetic equilibrium

4. No mutations For genetic equilibrium to occur, there must be no mutations, which introduce new alleles, and no Natural Selection can take place which gives any one phenotype a survival advantage over another.

4. No mutations For genetic equilibrium to occur, there must be no mutations, which introduce new alleles Mutations that change phenotype can affect an organism’s fitness(ability to survive and reproduce)

LEARNING OBJECTIVE 6. The Hardy Weinberg Principle

The Hardy-Weinberg Principle In order to tell whether or not Genetic Equilibrium is happening scientists use the Hardy-Weinberg Principle This equation compares how often an allele is found in a population to how often a phenotype is in a population

p2 + 2pq + q2 = 1 p2=the frequency of homozygous dominant genotype 2pq=the frequency of heterozygous genotype q2=the frequency of homozygous recessive genotype

In some populations, these conditions may be met or nearly met over long periods of time, and little or no Evolution occurs. BUT in most populations it is difficult for ALL conditions of Hardy-Weinberg to be met. Hank Video