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Sarah B. Carey

I am interested in the role of parent-offspring conflict in maintaining genetic variation for fitness within populations and its contribution to the evolution of differentiation among populations.

My dissertation is focused on how having separate sexes maintains genetic variation for fitness. Mosses are an excellent model system for the study of parent-offspring conflict because the diploid offspring (i.e. sporophyte) is nutritionally dependent on the haploid, maternal gametophyte for its entire life. In species that are dioecious (i.e. have separate sexes) theory suggests that the maternal genotype should limit the amount of nutrients allocated to any one offspring event while the paternal genotype is expected to promote an increase in nutrient transfer. I therefore hypothesize the site of nutrient transfer from the maternal gametophyte to the offspring sporophyte – that is, the placenta – will be enriched for transcripts with sex-biased expression. To test this hypothesis, I aim to use Laser Capture Microdissection combined with RNAseq of placental cells at multiple stages of development in the moss model system Ceratodon purpureus. In the long term I expect to find placenta-expressed transcripts that contribute to the abundant variation in spore production in natural populations of this species.