microevolution and natural selection 9/16-9/20

sexual selection

selection for traits that improve mating success

intrasexual selection

• selection within a sex

• male competition for the right to mate with a female

intersexual selection

• mate choice

• females choose the male they want to mate with

sexual dimorphism

• difference in appearance of males and females

• males look better so females will mate with them

quantitative character

characters that vary along a continuum

discrete character

• come in 2 forms

• not helpful for natural selection

mutation

• random changes in dna

• affect mostly populations with with short generational spans (ex. bacteria)

sexual recombination

sex shuffles alleles and deals them at random to offspring

diploidy

• two copies of each gene, one inherited from each parent (AA, Aa, aa)

• hides genetic variation in the form of recessive alleles that can skip a generation

heterozygotes

one recessive and one dominant gene (Aa)

balanced polymorphism

• gives heterozygotes an advantage

• how natural selection maintains diversity