NSF Postdoctoral Fellowship in Biology FY 2020: Investigation of the Ancestral Modulation Rule, a Proposed Rule for Reversal of Sex-biased Traits

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This action funds an NSF Postdoctoral Research Fellowship in Biology for FY 2020, Integrative Research Investigating the Rules of Life Governing Interactions Between Genomes, Environment and Phenotypes. The fellowship supports a research and training of the Fellow that will contribute to the area of Rules of Life in innovative ways. The remarkable diversity of characteristics biased toward one mating type or the other is underappreciated and often overlooked. Almost every trait with mating type-bias in one species can be found with the opposite mating type-bias in a different species. The fellow proposes to test an idea that the evolutionary history of these reversals predicts the physiological, genetic, and behavioral pathways that are responsible for the expression of a mating type-biased trait. This research will advance understanding of how mating type-biased traits develop and can be used to explain the diversity of mating type-biased traits within and across species. The Fellow will work to develop educational materials that present behavioral and evolutionary themes in ways that students can discover ideas for themselves so that the subjects are more approachable.Mating type-biased phenotypes ultimately feed back into evolution driving diversity and even speciation, thereby necessitating the need for a framework for studying biased trait evolution. Such an overarching framework would have predictive power to suggest testable hypotheses in numerous species even in cases where the patterns are not obvious. The Fellow’s proposed ancestral modulation rule, brings together apparently disparate results, identifying the time of evolutionary origin of the apparently reversed-biased phenotype as the explanation for which of two underlying mechanistic patterns should evolve. When a mating type-biased trait emerges de novo, new pathways and genes are co-opted and therefore rely on the mating type-typical hormones (altered control hypothesis); however, when the biased trait is reversed from the ancestral bias, increased sensitivity to the traditionally regulating hormone will evolve (altered sensitivity hypothesis) thereby preserving the ancestral genetic framework and possibly the plastic response to the environment as an atavistic trait. The Fellow will use several species of fishes (cichlids and gouramis) that have undergone shifts in mating type-biased traits (brood care, aggression, and ornamentation) to test if the ancestral modulation rule can correctly predict which hormonal control mechanisms are present. Results of this study will provide insight into the drivers and consequences of mating type-biased traits generally and reversed mating type-biased traits specifically, leading to an increased understanding of mating type-biased trait evolution. Educational outreach will be conducted as part of the project.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.