Maintenance of Genetic Variation Flashcards
what is the purpose of directional selection?
increase in fitness and removes disadvantageous alleles
how is genetic variation maintained?
mutation. genetic drift. directional selection. frequency dependent variation.
what is the mutation selection balance?
- mutation introduces lethal alleles and selection removes them
- selection is slow at removing alleles at low frequencies
how do lethal recessive alleles persist?
hide in the heterozygote as selection can’t act against them. eg genetic diseases
when are equilibrium frequencies higher?
- mutation rates are higher
- strength of selection is lower
what is heterozygote advantage?
where heterozyotes have a greater fitness than the homozygotes
what can heterozygote advantage lead to?
equilibirum
what is the highest allele frequency you can get with heterozygote advantage?
0.5 - will always produce homozygotes due to mendelian segregation
what is the effects of genotype environment interactions?
can maintain variation within populations - can occur within or between populations
what is pleiotropy?
single gene effects multiple traits
what is physical linkage
adjacent genes on a chromosome
what can selection on one trait lead to in connected genes?
correlated response in anoter
what can linkage disequilibirum lead to?
gene clusters
what are genetic correlations?
can change the repsonse to selection or be the reuslt of selection - 2 traits that seem to be genetically linked
what can positive selection lead to?
co-adapted traits
