Impact of bias in evolutionary mechanisms: migration among subdivided population and gene conversion among multigene family
Year: 2009
Type: preprint
Abstract: Two models of bias in evolutionary mechanism is presented: one of bias in migration in Wright’s island model and the other of bias in gene conversion among members of a multigene family in a panmictic population. The models have an identical diffusive limit for a large population size, where allele frequencies in each subpopulation of the n-island model are identical to allele frequencies in each locus of the n-gene family. The probability of fixation of a new mutant throughout the total population/gene family is obtained by the diffusion process. It is shown that the deviation of the probability of fixation from that without bias is proportional to one plus the number of migrants/converted alleles. For the island model with allele-dependent migration, an analogue of the coalescent genealogy, which we call the ancestral bias graph, is introduced. We present a recursion formula that can be used to compute the probability of obtaining a given sample. We apply our formula to data set of mouse histone gene family. It is suggested that bias in ectopic gene conversion, whose magnitude is orders of magnitude larger than that in allelic gene conversion, can be maintained in a population. Recently, evidence of the large impact of biased gene conversion on gene substitution is accumulating. The fact that the diffusion models for conversion bias and for migration bias are identical suggests that migration bias can also have large impact on genomic polymorphism and divergence in subdivided populations.
Source: arXiv (Cornell University)
Author: Shuhei Mano
Language: English
Subfield: Genetics
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W311039684