Finding genes that enable adaptation Flashcards
Examples of adaptive differentiation
Aphids to different host plants
Cichild fish to different water depths
Marine snails to different parts of rocky shore
Monkey flowers to different pollinators
What is the prediction
Genes responsible for these adaptive trait differences will be more strongly differentiated between populations than most neutral genes
Whats the Fst index
The interbreeding could be used as a measure of differentiation among subpopulations
Whats the Fst equation
Fst = (Ht - Hs)/ Ht
Ht: the expected heterozygosity in the total population
Hs: the average expected heterozygosity in the subpopulation
Whats the scale for FST
0-1
Whats an expection for neutral genes
If there is a barrier, the subpopulations have small number of individuals, neutral alleles start to diverge as well
What does drift depend on
N: effective size of each subpopulation
What does gene flow depend on
M: proportion of each subpopulation made up of immigrants
How do we calcualte Fst with an expection to neutral genes
Fst = 1/(1+4NM)
What are ways to sample differentiation of genes
Microstatellites, SNPS, sequencing the whole genome
What do microsatellites involve
Repeats of 2-5 base pairs
In non-coding regions
Have a high rate of mutation from slippage replication
Locus specific and highly polymorphic
Can be amplified by PCR easily
Range of scales
What do SNPs involve
One alteration in the bases
Can be in the coding or non coding region
More common than microsatellites
PCR products can be small
Fewer alleles per locus
What does sequencing the whole genome involve
Parts of the gene
More costly
More resolution
Can detect bigger mutations
Arabidopsis lyrate on serpentine soils
2 serpentine, 2 granitic
