BSC 201 Lecture Notes - Lecture 6: Genotype Frequency, Quantitative Genetics, Peppered Moth
Document Summary
Peppered moth example: single locus, 2 alleles, 2 phenotypes (light and black)- light is dominant, appears to be a regulatory gene. Controls the expression of melanin (dark pigment) in different parts of the body. B allele arises by mutation of b+ allele, and b+ allele arises by mutation of b allele. Remember occurrence of mutation is random, only spread may not be. Gene frequencies: p + q = 1 / q = 1 p. Hardy-weinberg equilibrium: used to mathematically model evolutionary change, represents null model for population genetics, no evolutionary change occurring. P, q, p2, q2, 2pq do not change over generations: assumes: no selection, infinite populations, no immigration/emigration, no mutation. Therefore, if a force of evolution is acting h-w equilibrium doesn"t occur. Evolutionary change: selection against white morphs increases frequency of b (increases p) and this will change offspring genotype frequencies.
