F13 lecture 8 v2

On and variaon within and between populaons g 33a two

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: essfully reproduce hIp://www.cartoonstock.com/lowres/amc0088l.jpg a simple model – island model the whole system = a metapopulaGon •  p and q subscripted for each subpopulaGon •  in each subpopulaGon: •  pt=pt- 1(1- m)+pm •  t = generaGon •  m = migraGon rate •  p = frequency of new alleles from immigrants change in p due to migraGon •  in each subpopulaGon •  dp = pt – pt- 1 •  =m(p - pt- 1) •  p is assumed to be the same across the metapopulaGon •  allele frequencies in the enGre metapopulaGon will converge to p migraGon •  keeps populaGons from diverging •  conversely, lack of migraGon leads to isolaGon and geneGc divergence of populaGons migra?on and varia?on within and between popula?ons •  fig 3.3A •  two of the populaGons start out at p=0 and p=1 respecGvely –  all of the variaGon is between populaGons –  no variaGon within these populaGons •  aUer 50 generaGons = both populaGons are at p=q=0.5 –  maximum within populaGon variatoin –  no between populaGon variaGon •  MIGRATION CONVERTS BETWEEN- POPULATION VARIATION TO WITHIN- POPULATION VARIATION inferring gene flow •  usually done by comparing within versus between populaGon variaGon •  if there is liIle variaGon between populaGons –  infer high gene flow •  if there is a lot of variaGon between populaGons –  infer liIle gene flow geneGc driU •  some terms –  metapopula?on (see above) –  popula?on structure = the degree of geneGc differenGaGon between populaGons or between subpopulaGons of a metapopulaGon –  panmic?c = no geneGc structure; no divergence between subpopulaGons •  each individual has an equal chance of maGng with any other individual in the enGre populaGon, regardless of where in the populaGon they are geneGc driU •  due to random changes in populaGon size –  also called “random driU” or “random geneGc driU” •  the smaller the populaGon size, the stronger the effect •  ulGmate result = alleles can go to 100% (fixaGon) by chance alone –  these can be neutral (no selecGve effect) –  they...
View Full Document

Ask a homework question - tutors are online