BIOL 522 Lecture Notes - Lecture 2: Coalescent Theory
Document Summary
Backward time approach = start with sample today and infer what parental generation looked like and continue working back - inference style/ economical way of using dat. Forward time approach = start with sample and look at offspring"s alleles, start with actual history and look at observed data. P(1) = probability of coalescing in 1st gen. N = number of generations back you have to go, n = population size. Time to common ancestor is the expected value of n (sum of n*probability of coalescent at n-th generation) = n. At any generation, there"s 1/2n chance of coalescence, so 10000*2 generations for humans * 30 years = At any time of a genome, we don"t share a human ancestor - the common ancestor was something like the ancestor to neanderthals/ denosivans , so diversity within humans can be shared with non human relatives.
