PhD projects Elsa Quicazan and Mike Fleuren

PIs: Bart Pollux and Johan van Leeuwen

Contrary to most fish species, fish of the Poeciliidae family give birth to live young. The internal development of their embryos lays a large burden on the swimming performance of the females. We hypothesize that two specific reproductive adaptations found in a number of species of Poeciliid fish can reduce the effect of pregnancy on swimming performance: placentation, in which the embryos are nourished through a dedicated structure during (part of) their development, and superfetation, the simultaneous presence of embryos of different developmental stages.

Swimming performance is measured on different levels: endurance swimming is measured in a flow tunnel while the anaerobic escape response is measured in a state-of-the-art 3D swimming arena enabling us to track the fish’s escape movement in the most natural-realistic way possible. Furthermore, we track the body shape changes that occur over time in three dimensions, measure the effect of pregnancy on metabolic rate and possible (secondary) effects of pregnancy on the muscle structure of female live-bearing fish.

By comparing the swimming performance in species with different levels of placentation and superfetation, we shed new light on why these reproductive traits have evolved.

We collaborate with Cees Voesenek on the 3D tracking of the swimming fish and David Reznick (Univ. of Riverside) on the evolutionary biology of the Poeciliidae.

This research line is sponsored by ALW/NWO grant ALW821.02.024.