Fixation and effective size in a haploid-diploid population with asexual reproduction

The majority of population genetic theory assumes fully haploid or diploid organisms with obligate sexuality, despite complex life cycles with alternating generations being commonly observed. To reveal how natural selection and genetic drift shape the evolution of haploid-diploid populations, we analyze a stochastic genetic model for populations that consist of a mixture of haploid and diploid individuals, allowing for asexual reproduction and niche separation between haploid and diploid stages. Applying a diffusion approximation, we derive the fixation probability and describe its dependence on the reproductive values of haploid and diploid stages, which depend strongly on the extent of asexual reproduction in each phase and on the ecological differences between them. Highlight - Classical models consider fully haploid or diploid populations - We model haploid-diploid life cycles allowing for asexual reproduction - We obtain the fixation probability of alleles subject to selection and drift - Reproductive values of haploid and diploid stages shape their evolution