Red Queen dynamics in Daphnia, the role of variable environment

Dr. Justyna Wolinska

The predominance of sexual reproduction poses a major evolutionary paradox. The Red Queen hypothesis argues that sexual organisms can outcompete asexual ones because parasites adapt to common genotypes and prevent them from fixation. However, examples of Red Queen dynamics in nature are surprisingly scarce. This scarcity could arise because screening methods do not adequately resolve genetic variation of hosts and parasites; alternatively, environmental variation could disrupt tight host-parasite coevolution. Here, I propose to look for Red Queen dynamics in a crustacean waterflea host (Daphnia) - microparasite system, using fine-scale field data and high-resolution molecular markers. I will seek experimental support for evolution of parasite pools (a key ingredient of Red Queen coevolution). Further, Red Queen predictions focus on tight genetic specificity of host-parasite interactions with little reference to their ecology. To investigate if heterogeneous environments influence parasite selection (and Red Queen dynamics), I will look for spatial evidence of coevolutionary “hot spots” and “cold spots”, within a large, well-studied lake. Next, I will explore how one important source of environmental variation (predator threat) alters the response of host genotypes to parasite-mediated selection. This project, a combination of intensive field sampling, advanced molecular techniques, and ambitious laboratory experiments, will advance the interface of ecology and coevolution of host-parasite interactions.