Ploidy composition in all-hybrid frog populations in relation to ecological conditions

Question: What explains the differences in ratios of diploid (LR) and two types of triploid frogs (LLR, LRR) among all-hybrid frog populations? Hypothesis: Ecological conditions favouring one (LL) or the other (RR) parental species also favour those triploids that carry two copies of the respective genome (dosage effect), whereas diploids dominate under intermediate conditions. Organism: European water frog (Pelophylax esculentus). Field site: Thirty-four natural ponds in the province of Skåne, southern Sweden. Methods: We caught more than 3000 frogs, determined their genotypes with microsatellites, and related the ploidy composition to several uncorrelated ecological parameters, including pond morphology, vegetation, and physical and chemical water parameters. Conclusions: We found a shift from predominantly LLR in small isolated ponds to more LRR in large wetland ponds. This parallels the preferences of the parental species LL and RR for small and large bodies of water, respectively. The effects that pond vegetation and physico-chemical water parameters exert on the parental species were not found in all-hybrid populations. This suggests that environmental parameters affect the genotype composition of all-hybrid populations less than populations containing the parental species. Pond-to-pond differences in LR, LLR, and LRR proportions seem to be better explained by differences in gamete production and thus inheritance patterns. Posted at the Zurich Open Repository and Archive, University of Zurich ZORA URL: https://doi.org/10.5167/uzh-38402 Originally published at: Jakob, C; Arioli, M; Reyer, H U (2010). Ploidy composition in all-hybrid frog populations in relation to ecological conditions. Evolutionary Ecology Research, 12:633-652. Ploidy composition in all-hybrid frog populations in relation to ecological conditions Christian Jakob, Martina Arioli and Heinz-Ulrich Reyer Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland