HardyWeinberg Equilibrium Honors Biology Is evolution occurring right

Hardy-Weinberg Equilibrium Honors Biology

Is evolution occurring right now? p How might a scientist tell if evolution is occurring within a population?

Hardy-Weinberg Theorem Biologists use models to study populations p Hardy-Weinberg equilibrium is a type of model p n Provides a framework for understanding how populations evolve

The Hardy-Weinberg Theorem p Uses frequencies of alleles in a population’s gene pool to determine if (micro)evolution is occurring n n If allele frequencies change over time, the population is evolving If allele frequencies are stable, the population is at equilibrium

Hardy-Weinberg Equilibrium Conditions Genotype frequencies stay the same (no microevolution) if all 5 conditions are met: 1. Very large population size 2. Isolation from other populations 3. No Mutations 4. Random Mating 5. No natural selection n

Hardy-Weinberg Equation p p+q=1 n n p p = frequency of dominant allele q = frequency of recessive allele p 2 + 2 pq + q 2 = 1 n n n p 2 = frequency of homozygous dominant genotype (AA) 2 pq = frequency of heterozygous genotype (Aa) q 2 = frequency of homozygous recessive genotype (aa)

Solve this story problem In pigs, the allele for black skin is recessive to pink skin. p B = pink; b = black p Calculate q 2 for the illustration shown below. p q 2 = 0. 25 (4/16) p

p Find q. n p Find p. n p q = 0. 5 p = 0. 5 Find 2 pq. n n 2 pq = 0. 5 This means 50% of the pink pigs are heterozygous.

Solve this story problem In a certain flock of sheep, 4 percent of the population has black wool and 96 percent has white wool. p If black wool is a recessive trait: p n n n What percentage of the population is homozygous black? (q 2) What percentage of the population is heterozygous for this trait? (2 pq) What percentage of the population is homozygous white? (p 2)