DEB: Genomics of Sexual Selection in Pipefishes and Seahorses

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Sexual selection is an important evolutionary mechanism that results in the evolution of extravagant ornaments, strong mating preferences, and differences between the sexes. Sexual selection also sets the stage for sexual conflict, a situation in which the evolutionary interests of the two sexes fail to coincide, resulting in traits or genes that can be beneficial to one sex but harmful to the other sex. While the effects of sexual selection and conflict on traits are well understood, little is known about how these mechanisms affect the genome. A key test of theory relating sexual selection, sexual conflict and genome evolution would entail genome comparisons in groups of related species in which some have had a history of strong sexual selection and some have had a history of weak sexual selection. In this project, the researchers will use seahorses and the related pipefishes to conduct such a test. Seahorses and some pipefishes are monogamous with long-term pair-bonds, and this mating system results in weak sexual selection and little sexual conflict. Other pipefishes have independently evolved polygamy (multiple mating by one or both sexes), which results in strong sexual selection and substantial conflict. The researchers will apply modern sequencing methodologies to delineate the impacts of sexual selection and conflict on genome evolution in these species. This project has significance well beyond seahorses and pipefishes, as many species, including humans, have had a recent evolutionary history involving sexual selection and conflict. This history can explain why the sexes are different at the level of the genome and why the same gene can have different effects in the sexes. This project will also train a new generation of graduate students and undergraduates in cutting-edge genomic techniques and statistical methodologies. In addition, it will expand the pipefish and seahorse research community by offering week-long workshops and a new wealth of publicly available genomic data.The project will involve a total of twelve taxa, including three seahorses and nine pipefishes, chosen for their phylogenetic relationships and known patterns of sexual selection. The seahorses (genus Hippocampus) and three of the pipefish species (genus Doryrhampus) are monogamous with pair-bonds, and the other six pipefish (three each from the genera Syngnathus and Nerophis) are polygamous with a history of strong sexual selection. The project will involve (1) the complete sequencing of the genomes of all twelve taxa, (2) comparative transcriptomics, which will examine patterns of sex-specific gene expression, and (3) comparative population genomics, which will detect contemporary genome-level selection. Data will be integrated across these three levels of approaches to understand the genome-level effects of sexual selection and sexual conflict in light of evolutionary theory.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.