Population ecology of (hemi-)clonal waterfrogs
Europe 1991-2012
According to evolutionary theory, hybrid species and species with clonal and semi-clonal reproduction are at a selective disadvantage compared to true species that reproduce sexually. Nevertheless, some of these species have existed for more than 200,000 generations and exhibit large ranges as well as high population densities.
In my research group, we used the semi-clonal pool frog (Pelophylax esculentus) – originally a hybrid between the small water frog (P. lessonae) and the lake frog (P. ridibundus) – as a model system to investigate the genetic, behavioural and ecological causes of this unexpected success. The hybrid reproduces hybridogenetically, i.e. prior to meiosis, it removes one of the parental species’ genomes from the germline and passes on the genome of the other parental species clonally to eggs or sperm. The results from our field studies, cross-breeding experiments in the laboratory and mathematical models showed that the size, composition and dynamics of populations are significantly influenced by the following three factors: 1) mating success of individuals from hybrid and parental species; 2) survival rates of parental species and hybrid offspring; 3) the type and proportion of polyploid hybrids.
These frog-specific findings can contribute to our understanding of various more general biological topics. These include sexual conflicts, the stability of hybrid zones, the evolutionary potential of (hemi-)clonal groups for speciation, the dynamics of coupled systems (e.g. parasite-host) and the question: How do individuals’ behavioural strategies influence the composition and dynamics of populations and ecological communities?
