title: Fixation Probability in a Haploid-Diploid Population.
abstract: Classical population genetic theory generally assumes either a fully haploid or fully diploid life cycle. However, many organisms exhibit more complex life cycles, with both free-living haploid and diploid stages. Here we ask what the probability of fixation is for selected alleles in organisms with haploid-diploid life cycles. We develop a genetic model that considers the population dynamics using both the Moran model and Wright-Fisher model. Applying a branching process approximation, we obtain an accurate fixation probability assuming that the population is large and the net effect of the mutation is beneficial. We also find the diffusion approximation for the fixation probability, which is accurate even in small populations and for deleterious alleles, as long as selection is weak. These fixation probabilities from branching process and diffusion approximations are similar when selection is weak for beneficial mutations that are not fully recessive. In many cases, particularly when one phase predominates, the fixation probability differs substantially for haploid-diploid organisms compared to either fully haploid or diploid species.
authors.affiliation: JSPS Research Fellow, Department of Evolutionary Studies of Biosystems, School of Advanced Sciences, SOKENDAI (The Graduate University for Advanced Studies), Hayama, 240-0193, Japan bessho_kazuhiro@soken.ac.jp otto@zoology.ubc.ca.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Bessho
authors.affiliation: Department of Zoology, University of British Columbia, Vancouver, V6T 1Z4, Canada bessho_kazuhiro@soken.ac.jp otto@zoology.ubc.ca.
authors.forename: Sarah P
authors.identifier: 0000-0003-3042-0818
authors.initials: SP
authors.lastname: Otto
mesh_terms: D000483:Alleles; D004171:Diploidy; D005828:Genetics, Population / Q000379:methods* / Q000706:statistics & numerical data*; D006238:Haploidy; D008957:Models, Genetic; D009154:Mutation; D011157:Population Dynamics; D011336:Probability; D012641:Selection, Genetic
keywords: Moran model; Wright–Fisher model; fixation probability; haploid-diploid life cycle; variance effective population size