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Research Agenda
I am interested in the study of sexual selection and sexual conflict, especially at the genomic and molecular levels. Recently described genomic and molecular evolutionary patterns associated with reproductive processes have become the center of much attention. Male-biased patterns of gene expression, for example, are a hypothesized evolutionary response to sexual selection (Singh and Kulathinal, 2005). Furthermore, many gonad-associated protein-coding genes have undergone positive selection and demonstrate a faster rate of evolution compared to genes expressed elsewhere in the soma (reviewed in Swanson and Vacquier, 2002).
We have used commercial oligonucleotide microarrays to elucidate sex- and gonad-biased patterns of gene expression in the zebrafish, Danio rerio. In addition we are performing molecular evolutionary analyses (including tests for positive selection) of ovary- and testis- biased genes whose orthologs have been sequenced in multiple Danio species.
Other work involves a similar approach in the family Syngnathidae (pipefishes and seahorses). Using next generation sequencing as a powerful scan of pipefish transcriptomes, we are measuring gene expression patterns specific to sex, the gonads, and male pregnancy. The Gulf pipefish Syngnathus scovelli demonstrates extreme sex-role reversal, so if sexual selection does play a substantial role in sex-specific gene expression patterns, we might expect a shift towards female-biased expression in this species. Furthermore, if sexual selection and/or intersexual conflict drive the evolution of reproductive proteins, we can make a priori predictions about lineage-specific patterns of molecular evolution based on extensive mating system variation across the family. The two genera Syngnathus and Hippocampus (seahorses) provide an ideal group for this type of study because they include species with monogamous, polyandrous, and polygynandrous genetic mating systems.
Additional projects include parentage analysis and the estimation of sexual selection gradients in various syngnathid species, a replication of Bateman’s classic sexual selection study in Drosophila (with Nick Ratterman), biogeography of Syngnathus species (with Kenyon Mobley), genomic imprinting of male pregnancy genes, and molecular evolution of Drosophila courtship genes (with Ginger Carney).
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