The Hardy-Weinberg Principles Changing Populations Evolution • Evolution is caused by the changing of populations. Changing Populations • Populations change at the genetic level. To get the population to change the gene pool must change. Gene Pool • Gene pool- all of the alleles in a population Ex. 500 Flowers(show incomplete dominance) 320 RR (red) 160 Rr (pink) 20 rr (white) Allele Frequency • Allele frequency is the proportion of each allele found in the gene pool. • p = one allele (usually dominant) • q = the other allele (usually recessive) Ex. What would the allele frequency be for “R” and “r” in the wild flower population? Hardy-Weinberg Equation • This equation shows the frequency of each genotype we would expect to see based on the allele frequencies in the population. • p2 + 2pq + q2= 1 Ex. What would the genotype proportions be in the flower population? Hardy-Weinberg Equilibrium • If the genotype frequencies in the actual population match the proportions in the equation, then the population is in Equilibrium and not evolving. • Ex. Is the flower population Evolving? 5 conditions • For a population to stay in equilibrium (not evolve) five things must be true. • 1 No Mutations • 2 Random Mating (no sexual selection) • 3 No Natural Selection • 4 No Gene flow • 5 Very Large Population (no Genetic Drift) • These five things change the proportion of genotypes or the allele frequencies Example • In a population of 300 Snakes 130 are homozygous dominant for black scales. 70 are homozygous recessive and have red scales. 100 are Heterozygous are have a checker board pattern. Is this population evolving?