F-statistics under alternation of sexual and asexual reproduction: a model and data from schistosomes (platyhelminth parasites).

• Published in: Molecular Ecology
• Main Authors: Prugnolle, Franck, Roze, Denis, Théron, André, de Meeûs, Thierry
• Other Authors: Génétique et évolution des maladies infectieuses (GEMI), Université Montpellier 1 (UM1)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD France-Sud ), Centre d'Etude sur le Polymorphisme des Micro-Organismes (CEPM), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD France-Sud ), Parasitologie fonctionnelle et évolutive 2003-2006 (PFE), Université de Perpignan Via Domitia (UPVD)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2005
• Subjects: Asexual reproduction; Complex life cycle; F-statistics; Heterozygote excesses; Schistosomes; MESH: Animals; MESH: Comparative Study; MESH: Guadeloupe; MESH: Male; MESH: Models; Genetic; MESH: Muridae; MESH: Platyhelminths; MESH: Population Dynamics; MESH: Rats; MESH: Reproduction; MESH: Research Support; Non-U.S. Gov't; MESH: Schistosoma; MESH: Sex Factors; MESH: Variation (Genetics); MESH: Female; MESH: Genetics; Population; [SDV.BID.EVO]Life Sciences [q-bio]/Biodiversity/Populations and Evolution [q-bio.PE]; Rattus rattus
• Online Access: https://hal.science/hal-00104523; https://doi.org/10.1111/j.1365-294X.2005.02541.x

Accurate inferences on population genetics data require a sound underlying theoretical null model. Nearly nothing is known about the gene dynamics of organisms with complex life cycles precluding any biological interpretation of population genetics parameters. In this article, we used an infinite island model to derive the expectations of those parameters for the life cycle of a dioecious organism obligatorily alternating sexual and asexual reproductions as it is the case for schistosomes (plathyhelminth parasites). This model allowed us to investigate the effects of the degree of mixing among individuals coming from different subpopulations at each new generation (represented in the model by the migration rates before and after clonal reproductions) and the variance in the reproductive success of individuals during the clonal phase. We also consider the effects of different migration rates and degrees of clonal reproductive skew between male and female individuals. Results show that the variance in the reproductive success of clones is very important in shaping the distribution of the genetic variability both within and among subpopulations. Thus, higher variance in the reproductive success of clones generates heterozygous excesses within subpopulations and also increases genetic differentiation between them. Migration occurring before and after asexual reproduction has different effects on the patterns of F(IS) and F(ST). When males and females display different degrees of reproductive skew or migration rates, we observe differences in their respective population genetic structure. While results of the model apply to any organism alternating sexual and clonal reproductions (e.g. all parasitic trematodes, many plants, and all aphididae), we finally confront some of these theoretical expectations to empirical data from Schistosoma mansoni infecting Rattus rattus in Guadeloupe.