Lecture 9 Flashcards
(24 cards)
what is inbreeding?
individuals mate with relatives
what is disassortive mating?
genotypes that are different from one another may mate more often than expected
what is assortive mating?
genotypes that are similar to one another may mate more often than expected
True or False: one generation of not inbreeding, removes all effects of inbreeding previously
true
what is the inbreeding coefficient?
probability that two alleles are identical by descent
What does identical by descent mean (IBD)?
identical alleles that someone inherited as they came from the same ancestor (due to inbreeding)
what is more extreme: inbreeding or self fertilization?
self fertilization
What happens in the case of self fertilization?
- all progency of homozygotes are themselves homozygotes
- half of te progeny of the heterozygotes are heterozygotes and half are homozygous
- each generation, the heterozygosity is reduced by half
Do individuals who undergo self fetrtilization still have independent assortment?
yes
Does inbreeding change genotypes or alleles?
inbreeding changes genotypes, not alleles
What does one generation of random mating do for a previously inbred population?
will restore HWE
What is “F”?
the inbreeding coefficient
How do we calculate F?
Two ways:
1. measure individual F for many individuals and find the mean
2. measure reduction in heterozygosity in the population
What does it mean if F=0?
there is HWE within populations. the expected number of heterozygotes equals the observed number of heterozygotes
What does it mean if F=1?
all individuals within the populations are homozygotes (either allele)
Typically what is the value of F?
usually much less than 0.5, except in highly inbred populations or selfing species
what is inbreeding’s genetic drift on individuals?
causes individuals to contain alleles that are identical by descent from a common ancestor
What is inbreeding’s genetic effect on populations?
causes a loss of heterozygosity
what is the positive phenotypic effect of inbreeding?
causes individuals to be uniform, which is really useful for breeding and agriculture
what is the negative phenotypic effect of inbreeding in a population?
causes inbreeding depression (reduced vigor, longevity, fertility) by exposing recessive alleles
Where are deleterious alleles more likely to combine?
in homozygotes
What does inbreeding depression result in?
reduced fitness
What is the difference between inbreeding and assortive mating?
inbreeding effects the whole genome while assortive mating is also selection for one trait, not the whole genome
what is assortive mating?
like genotypes choose like genotypes (only for one genotype of interest such as height)
