Massive congratulations to Max Tschol for brilliantly defending is PhD!!

Max defended his thesis titled “Sexual selection in small and spatially structured populations” where he used individual-based models to investigate how sexual selection affects population persistence via a variety of mechanisms, and considered different spatial scales spanning from single isolated populations to the dynamics of metapopulations and species’ ranges.

1. He investigated the potential for sexual selection to reduce genome-wide genetic load within small populations and under consideration of environmental variation in sexually selected traits (paper coming soon!). Results showed that phenotypic sexual selection has conflicting genetic effects, whereby the balance between increased purging of deleterious mutations and increased genetic drift is critically mediated by the degree of environmental variation.
2. He put forward a novel mechanism for the maintenance of a costly female preference for male display trait that might operate when spatial population structure is present (Tschol et al. 2022, Evolution). Particularly low dispersal and small population sizes were conducive to the maintenance of costly female preference by creating a landscape of spatially varying sexual selection, where dispersal caused male immigrants to be on average maladapted to the locally sexually selected environment.
3. He provided the first model that explicitly considers the operation of sexual selection within a species’ range context. He investigated how species’ range limits could be affected by the population level consequences of evolving sexually selected traits once population densities become low enough for mate limitation and demographic stochasticity to impact population extinction and colonisation. Range limits were highly contingent upon the mechanism of sexual selection, the costs to sexually selected traits and the mating system (paper coming soon!).