ANT LIA: Collaborative Research: Evolutionary Patterns and Mechanisms of Trait Diversification in the Antarctic Notothenioid Radiation

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Part I: Nontechnical description The ecologically important notothenioid fish of the Southern Ocean surrounding Antarctica will be studied to address questions central to polar, evolutionary, and adaptational biology. The rapid diversification of the notothenioids into 120 species following a period of Antarctic glaciation and cooling of the Southern Ocean is thought to have been facilitated by key evolutionary innovations, including antifreeze glycoproteins to prevent freezing and bone reduction to increase buoyancy. In this project, a large dataset of genomic sequences will be used to evaluate the genetic mechanisms that underly the broad pattern of novel trait evolution in these fish, including traits relevant to human diseases (e.g., bone density, renal function, and anemia). The team will develop new STEM-based research and teaching modules for undergraduate education at Northeastern University. The work will provide specific research training to scholars at all levels, including a post-doctoral researcher, a graduate student, undergraduate students, and high school students. The team will also contribute to public outreach, including, in part, the develop of teaching videos in molecular evolutionary biology and accompanying educational supplements.Part II: Technical descriptionThe researchers will leverage their comprehensive notothenioid phylogenomic dataset comprising 250,000 protein-coding exons and conserved non-coding elements across 44 ingroup and 2 outgroup species to analyze the genetic origins of three iconic notothenioid traits: (1) loss of erythrocytes by the icefish clade in a cold, stable and highly-oxygenated marine environment; (2) reduction in bone mass and retention of juvenile skeletal characteristics as buoyancy mechanisms to facilitate foraging; and (3) loss of kidney glomeruli to retain energetically expensive antifreeze glycoproteins. The team will first track patterns of change in erythroid-related genes throughout the notothenioid phylogeny. They will then examine whether repetitive evolution of a pedomorphic skeleton in notothenioids is based on parallel or divergent evolution of genetic regulators of heterochrony. Third, they will determine whether there is mutational bias in the mechanisms of loss and re-emergence of kidney glomeruli. Finally, identified genetic mechanisms of evolutionary change will be validated by experimental testing using functional genomic strategies in the zebrafish model system.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.