15.3b Hardy Weinberg Equilibrium Hardy-Weinberg Equilibrium Section 15.3b H.G. Hardy Wilhelm Weinberg Gene Pools · combined genetic info of all the members of a population · allele frequency - measure of how common a certain allele is in a population aka relative frequency # of times an allele(T) occurs in a gene pool compared to other alleles (t) # of specific allele (T or t) total # of alleles in the gene pool Gene Pool Practice 15 peccaries in a population BB or Bb = long bristles bb = short bristles If 6 alleles in the population are the b variety and 24 are of the B variety, what are the allele frequencies? B = b = *allele frequency equals the # of times an allele occurs in a gene pool divided by the total # of allele in the gene pool Hardy-Weinberg Equilibrium · allele frequencies in a population will remain constant unless one or more factors (5) cause those frequencies to change · populations NOT in H-W equilibrium are evolving · all Populations almost all of the time are evolving exception - Horseshoe crab Genetic Equilibrium · allele frequencies remain constant · 5 conditions are required to maintain genetic equilibrium 1. very large populations 2. no gene flow 3. no mutations 4. no sexual selection 5. no natural selection H-W Rules 1. very LARGE population - genetic drift (random chance) has less effect on a large population 2. NO gene flow - gene pool must be kept together and separate from other populations no emigration (out) or immigration (in) 3. NO mutations - mutations lead to new alleles 4. NO sexual selection - all members of a population must have equal opportunity to produce offspring NO sexual selection (females can't be picky) 5. NO natural selection - no phenotype can have a selective advantage (normal distribution)