Bio 321 F13 lecture 8 v2

Phenotypically yellow males crossed to phenotypically

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Unformatted text preview: yellow+/ yellow Homework 1 review b) phenotypically yellow males to yellow/yellow+ heterozygous females yellow/Y males x yellow/yellow+ females -> males 50% yellow body bolor, 50% yellow+ body color; 50% yellow+/Y; 50% yellow/Y -> females 50% yellow body bolor, 50% yellow+ body color; 50% yellow/yellow; 50% yellow/ yellow+ Homework 1 review Homework 1 review Homework 1 review b) What are the coefficient of coincidence and Interference measures in this three gene interval? observed frequency of double recombinants = (14+13)/2940 = 0.009 expected frequency of double recombinants = (rf between A and C)*(rf between C and B) = (0.084)*(0.126) = 0.011 coefficient of coincidence = observed freq of doubles/expected freq of doubles = 0.009/0.0011 = 0.82 interference = 1 - c of c = 1 – 0.82 = 0.18 (positive interference) changes in allele frequency •  can be caused by –  mutaGon –  migraGon (gene flow) –  selecGon –  geneGc driU mutaGons •  base subsGtuGons •  inserGon- deleGons (“indels”) –  may cause frame shiUs in protein coding regions –  transposible element inserGons •  chromosome rearrangements –  inversions –  translocaGons populaGon change by mutaGon alone is very slow mutaGon rates •  generally 1x10- 4 to 1x10- 5 per locus per generaGon •  vary across the genome –  hot spots and cold spots •  vary between species hIp://www.nature.com/scitable/content/19266/ pierce_table_17_3_FULL.jpg migraGon •  migraGon = movement of individuals between populaGons •  gene flow = movement of genes between populaGons •  migraGon can occur without gene flow –  if immigrants don’t successfully 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...
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This note was uploaded on 10/01/2013 for the course BIO 321 taught by Professor John during the Spring '12 term at SUNY Stony Brook.

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