Functional advantage of the Placenta and Superfetation in Live-bearing Fish

Adaptation requires a phenotypic change due to selection that can be passed on to the offspring. Exploring selective forces and the evolutionary potential of traits, therefore, is fundamental to understand how the diversity of traits evolve and hence address a key challenge in evolutionary biology.

In my MSc project, I studied metabolic adaptations by quantifying the form and strength of selection acting upon body mass and resting metabolic rate and the amount of phenotypic change that is heritable. Specifically, I used individual-based data from a wild population of snow voles (Chionomys nivalis).

Now, in my PhD project, I am focusing on the evolution of complex reproductive adaptations, such as placentation and superfetation. The placenta is a highly complex structure that evolved throughout the animal kingdom and several times within the fish family Poeciliidae. Although this is indicative of a selective advantage of placentation, the causes and consequences of placental evolution remain poorly understood.

Poeciliopsis retropinna female containing embryos at three different developmental stages
Poeciliopsis retropinna female containing embryos at three different developmental stages

My goal is to (i) understand how locally reigning environmental conditions affects variation in placentation, superfetation and other life-history traits among natural populations of the live-bearing fish species Poeciliopsis retropinna in Costa Rica, (ii) quantify the relative importance of genes and environment in shaping this variation, (iii) to examine its consequences for body morphology, physiology, and locomotor performance during gestation, and (iv) test whether it is target of selection. 

By studying the causes and consequences of variation in placentation and superfetation, my project is expected to provide an adaptive explanation for why and a mechanistic explanation for how the placenta evolved.