Does the placenta drive the evolution of sexual selection?

PI: Dr. B.J.A. Pollux (for more background information on this project visit the my website)

During my MSc Ecology at the VU University in Amsterdam I became interested in studying evolutionary questions at a genetic level. My first MSc thesis focused on the evolutionary loss of a trait in parasitic wasps. I analysed the loss of trait, i.e. lipid synthesis, in these wasps using a bioinformatics approach. In my second MSc thesis I studied the genetic structure of slow worm populations in The Netherlands. In this study I sed genetic markers to analyse the genetic divergence of populations.

Now, during my PhD I will focus on the question: what are the consequences of the evolution of a complex trait, the placenta, on sexual selection in the live-bearing fish family Poeciliidae?

The placenta is a complex structure that not only evolved in mammals but throughout the animal kingdom. Especially interesting is the live-bearing fish family Poeciliidae, in which several species evolved a placenta independently. This suggests that it confers an adaptive advantage, yet its potential advantages have remained largely unclear. It has been argued that the evolution of such an intimate interaction between mother and child during pregnancy could lead to a conflict of interest between the two parties, i.e. parent-offspring conflict. This conflict is expected to encourage the mother to select for genetically fitter offspring by use of post-copulatory sexual selection instead of ‘costly’ mate choice.

My research focuses on sexual selection in the live-bearing fish family Poeciliidae, and addresses the question:  does the evolution of a placenta cause a conflict-driven shift from pre- to post-copulatory sexual selection? I will study this by use of genetic paternity assignments, mate choice experiments and comparative analyses of sexual selected characteristics in Poecilliidae species (with and without a placenta). Moreover, in my study I will focus on several poecliid species that co-occur in the same river drainages in Costa Rica, which enables me to exclude disturbing environmental variables in the analyses.

By studying the consequences of the evolution of the placenta on sexual selection, this research can provide new key insights in parent-offspring conflict and how this influences the relative importance of pre- and post-copulatory sexual selection.