2 19 15 Microevolution changes in gene or allele frequency 1 generation to next Evolution is descent with modification changes FORMULA of copies of an allele total of alleles for the same gene in the population Gene genetic makeup Phenotype physical DD homozygous dominant Dd heterozygote dd recessive allele Describe population Allele frequency Make population change allele frequency Natural selection Mutation Migration If population small can change quickly If non random mating population can change Special case if population is in equilibrium not changing Hardy Weinberg equilibrium P frequency of dominant allele D example p 0 6 or 60 Q frequency of recessive allele d example q 0 4 or 40 P Q 1 P 2 2PQ Q 2 1 P 2 gives us freq of DD Q 2 gives us freq of dd 2pq gives us freq of Dd Can use a Punnett square to determine frequency in next generation Natural selection Differential survival and reproduction Does not create but acts on variation that is present Molds evolution Adaptations features that provide selective adaptation because they improve ability to survive and reproduce 3 modes 1 Directional 1 phenotype favored over other 2 Disruptive extreme phenotypes are favored over intermediate 3 Stabilizing intermediate phenotype is favored over extreme phenotype phenotypes Distinguished by effects on phenotypes in population Bacteria that are resistant to antibiotics have an adaptive trait that non resistant bacteria lack When antibiotics are administered resistant bacteria are strongly selected for Antibiotics cannot create resistant to allele Subcategories Artificial selection FIGURE 12 5 Sexual selection Sickle Cell Anemia Selective breeding Helped Darwin form theory of evolution by natural selection Single mutation having big effect Can trace effect DNA Protein Disease Example of incomplete dominance heterozygote partial expression Red and white pink Hemoglobin molecule read pic on slides Glu Val change in 1 amino acid Cascading effect cells sickle block passages oxygen decreases causing more sickling extreme pain and damage to organs Example of incomplete dominance Sick cell disease Homozygous for trait Sickle cell trait Heterozygous Normal red blood cells Homozygous for normal Affects 1 out of 5 African Americans Comes from tropical Africa Confers resistance to malaria Adaptive Heterozygote advantage hetero favored over homo Darwin 1871 Sexual selection 1 2 Intra sexual competition Intersexual choice