Dunn, D. W. | bioRxiv Science

bioRxiv2019

A generalized framework of AMOVA with any number of hierarchies and any level of ploidies

The analysis of molecular variance (AMOVA) is a widely used statistical model in the studies of population genetics and molecular ecology. The classical framework of AMOVA only supports haploid and diploid data, in which the number of hierarchies ranges from two to four. In practice, natural populations can be classified into more hierarchies, and polyploidy is frequently observed in contemporary species. The ploidy level may even vary within the same species, even within the same individual. We generalized the framework of AMOVA such that it can be used for any number of hierarchies and any level of ploidy. Based on this framework, we present four methods to account for the multilocus genotypic and allelic phenotypic data. We use simulated datasets and an empirical dataset to evaluate the performance of our framework. We make freely available our methods in a software, POLYGENE, which is freely available at https://github.com/huangkang1987/.

genetics↗

bioRxiv2019

Genotypic frequencies at equilibrium for polysomic inheritance under double-reduction

Polyploids are organisms whose genomes consist of more than two complete sets of chromosomes. Both autopolyploids and allopolyploids may display polysomic inheritance. A peculiarity of polysomic inheritance is multivalent formation during meiosis resulting in double-reduction, which occurs when sister chromatid fragments are segregated into the same gamete. Double-reduction can result in gametes carrying identical-by-descent alleles and slightly increasing homozygosity. This will cause the genotypic frequencies to deviate from expected values and will thus bias the results of standard population genetic analytical methods used in molecular ecology and selective breeding. In this study, we extend existing double-reduction models to account for any even level of ploidy, and derive the symbolic expressions for genotypic frequencies via two methods. Inbreeding coefficients and heterozygosity under double-reduction and inbreeding are also calculated. Numerical solutions obtained by computer simulations are compared with analytical solutions predicted by the model to validate the model.

genetics↗