Research Interests
My dissertation currently focuses on better understanding the evolutionary mechanisms that generate and maintain genetic diversity in the wild. These mechanisms include admixture, recombination, mutation, and natural selection. My first aim examines the evolutionary history of Daphnia, my second aim simulates the allelic turnover of sexual plasticity, and my third aim is an experimental examination of clonal selection and competition across asexual lineages of Daphnia.
01
Adaptive divergence of Daphnia
Species identification remains a contentious issue in biology. A collective emphasis on better population sampling and genome-wide sequencing has reclassified many model organisms into more resolved clades. Here, I am studying the evolutionary history and divergence of the Daphnia pulex complex. To date, I am using public sequencing data and wild-sequenced Daphnia to study admixture, genetic differentiation, and shared polymorphisms across North American and European species.
02
Evolutionary turnover of sexual plasticity
Many species can switch between asexual and sexual reproduction depending upon environmental conditions. For instance, some invasive species will exploit new environments with asexual growth, expanding their population exponentially. The genetics of this system interest me and I want to model this within a theoretical framework using forward-genetics simulations like SLiM.
This experiment will have me compete crossed offspring in mesocosms to examine the competitive dynamics within a pedigreed population. I hypothesize to find that the fittest clones will rise to high frequencies and have mainly asexual reproduction.
03
Clonal selection and competition in Daphnia
Background: The role of sex remains controversial in evolution. While it is often accepted that sex can function as a mechanism that provides natural selection with variation to act upon [via recombination], sexually reproducing species face a challenge since the fitness of sexual females is half that of clonal females. Facultative sex, the capacity of organisms to switch between clonal and sexual reproductive modes, has been proposed as “the best of both worlds” as it allows organisms to benefit from occasional recombination while minimizing the “cost of sex”. The dynamics of facultative sex are often correlated with metrics of ecological quality and resource abundance. For example, sexual episodes often take place prior to periods of ecological stress, such as overwintering. Empirical studies across many facultative sexual species has shown that clonal diversity erodes over time following these sexual episodes. Yet, we do not know whether clonal erosion occurs due to the action of natural selection on clonal lineages, or if it is due to the stochastic loss of clones through genetic drift. By understanding how phenotypic variation in reproductive strategies are associated with clonal selection, we can expand our knowledge of natural selection and genetic drift within heterogeneous environments.