Lecture 10 Flashcards
(21 cards)
What is gene flow?
Movement and establishment of alleles
What are the two events required for gene flow?
gene movement and gene establishment
What is gene movement?
- movement of individuals
- movement of their gametes
What is gene establishment?
- survival
- reproduction
What are the different population subdivisions?
- no subdivision
- extreme subdivision (no migration, no gene flow)
- some subdivision (some migration, some gene flow)
What are the two ways we measure migration (gene flow)?
- direct methods (ex. mark and recapture)
- indirect methods (ex. molecular marker variation)
What does it mean when a population is genetically differentiated?
when populations differ in allele frequencies
What does it mean when two adjacent populations are genetically differentiated?
gene flow is not happening between them
What is differentiation is measured with?
Fst
What does Fst measure?
variation in allele frequencies among populations. Ranges from 0-1
What does Fst compare?
compares the average expected heterozygosuty of individual subpopulations (s) to the total expected heterozygosity if the subpopulations are combined (t)
What does a Fst value of 1 mean?
complete isolation between subpopulations. They are fixed for different alleles
What does an Fst value of 0 mean?
all subpopulations have the same allele frequencies (panmixis)
how do gene flow and genetic drift interact?
gene flow balances with genetic drift causing populations to be differentiated from one another
When does genetic divergence increase between subpopulations in terms of distance?
genetic divergence between pairs of populations increases with the geographic distance between them
How does population subdivision impact genetic drift?
population subdivisions enhances the effects of genetic drift,
How does gene flow counteract subdivision?
by homogenezing allele frequencies, making allele frequencies more similar among populations
How does population subdivision cause some level of inbreeding?
- reduced mating pool
- more alleles are identical by descent
Since selection can affect average heterozygosity, what do we do for testing?
we use non-coding/neutral loci for tests
What is a useful metric for quantifying the degree of inbreeding and the amount of population structure?
average heterozygosity
How does population structure imapct genetic variation?
can add to it or reduce it
