mechanisms tha preserve genetic variation
Diploidy: two copies of each chromosome. genetic variation is hidden in heterozygotes, the recessive allele is hidden so it isnt acted against. variation is stored for later generations
Balancing selection: when 2 traits or forms of a pop are maintained (instead of the dominant ONE)
Heterozygote advantage: imtermediate and both homos are preserved in pop. / heterozygotes have greater fitness than the two homozygotes ex: malria resistant gene
Frequency dependant selection: favors the pheontype that is less favored/ common phenotypes are selected against b/c fitness declines when its too common
neutral variation: selection where there is no specific advantage b/c DNA variation doesnt effect fitness. change comes as a result of genetic drift.