Background. All organisms live in environments that vary through time and space. In response to fluctuations in aspects of the biotic and abiotic environment, many populations rapidly adapt as they track the environment. Such non-anthropogenic environmental change is often caused by genetic shifts at many loci that underly quantitative traits. However, we have little knowledge of the evolutionary dynamics of such loci and how fluctuations of these alleles affects patterns of genetic variation genome-wide. For instance, are these alleles old or do they go to fixation often and subsequently arise again de novo? Do fluctuations at these loci substantially alter patterns of polymorphism at linked neutral sites? We address these basic questions using Daphnia as a model system

Current project - dynamics of predation induced adaptation in Daphnia. In collaboration with Andrew Beckerman at Univ. of Sheffield and Peter Ralph at USC, we are investigating the evolutionary history of loci that control quantitative genetic variation in predation defensiveness in Daphnia pulex. In response to midge predation, Daphnia grow small spikes on their back (‘neck-theeth’) but the ability to respond midge varies through space and, most likely, seasons. We are currently studying the evolutionary history of loci associated with neck-tooth induction through quantitative- and population-genomic analyses. This work seeks to examine the long term history of rapid adaptation to fluctuations in predation pressure through direct examinination of resurrected Daphnia lineages while simultaneously predicting adaptive evolutionary outcomes in the near future. 

In addition to examining adaptive dynamics in response to predation regime, our work on Daphnia will bear direct relevance to our understanding of adaptation to novel anthropogenic stressors as well as adaptation to anthropogenic climate change.