Reproductive digestion and its repercussions for coevolution
Research on the evolution of reproductive barriers during incipient speciation has typically focused on either pre-copulatory or post-zygotic processes. However post-mating, pre-zygotic (PMPZ) interactions between males and females may play an important, yet underexplored, role in the early stages of speciation. Such PMPZ interactions are shaped by both sexual conflict and cooperation, and preliminary observations suggest they evolve rapidly. Here, I use butterflies to explore the interaction between the female reproductive tract and the male ejaculate. Female butterflies have a specialized reproductive organ, the bursa copulatrix, which receives and digests the male ejaculate, or spermatophore. Spermatophore proteins aid in the cooperative venture of egg production, but also function to manipulate female remating rate, resulting in conflict between the sexes over remating frequency. In the Cabbage White butterfly, Pieris rapae, I discovered that females of the North American subspecies experience difficulty degrading spermatophores from males of the Japanese subspecies. I hypothesize that this mismatch is due to rapid evolution at spermatophore-bursa biochemical interfaces. I first identified spermatophore proteins and bursal enzymes responsible for spermatophore digestion using bioinformatic and biochemical techniques. I am now investigating divergence of spermatophore and bursal proteins using RNA-seq and Pool-seq in both subspecies with the aim to contrast the observed divergence in regulatory and coding sequences between the subspecies. I will use this work to discuss the relative contributions to phenotypic divergence and reproductive incompatibility in the context of rapid evolution of PMPZ interactions under conditions of both sexual conflict and cooperation.
21 Feb 2018
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