topic 5

Any type of mating where mate choice is based on phenotype -phenotype based matings that have a higher or lower frequency than expected by chance in a randomly mating population

individuals mate with others who are phentopically similar to them -in NA, this occurs for height, weight, IQ scores, socieconomic variables

indiv choose mates that are phenotypically different than them -relatively rare, result in more diversity

Result in H-W disequilibrium, but ONLY for those genes associated with the traits involved

independent evolution of similar traits, starting from a similar ancestral condition. Ex. 3 spined stickle back which evolved via positive assortative mating and speciation,evolution of some traits was seen in 3 separate lakes

Mating between relatives • effect: increases homozygosity at ALL loci • on its own, not a mechanism of evolution (does not change allele frequencies, though it changes genotype frinbredding • self fertilization: strongest form of inbreeding (this is not a form of asexual mating) • increases homozygosity and autozygosity • retard the rate of gametic disequ’m (in double het’s)

2 alleles are identical by descent if they arose by replication from the same copy of an allele in an ancestral population

an individual that possesses two alleles at locus identical by descent (can only be homozygous)

An individual that possesses two alleles at a locus that are not identical by descent (could be heterozygous or homozygous)

-Fractional reduction in heterozygosity in comparison in heterozygosity in comparison to a randomly mating population • F gives the probability that an individual in pop’s is autozygous (if no other forces are playing) • also gives probability that any two randomly chosen alleles from a pop’n are identical by decent (if no other forces are playing)

-inbreeding increases probability that a deleterious recessive allele occur in a homozygous form

An increase in the average population fitness as a result of a reintroduction of genetic diversity (from another population)

• opposite of inbreeding • increases heterozygosity (excess) at all loci • negative value of F • Outbreeding coefficient= -F (same formula)

sometimes translocation of individuals from one pop’n to another can a reduction in fitness; this can occur is the pop’ns have local adaption (so heterozygotes are not adapted to either environment) -ex: Garter snakes (colour patterns and escap mechanisms - stripes: keep moving and not seen and blotches: dart and stop) Mix b/w the two had higher mortality than either. -key: local adaptation is impaired