Exploring the genomics of convergent snout elongations in deep-sea fishes

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Explaining how similar traits have independently evolved in distantly related organisms is a central goal of evolutionary biology. Among vertebrates, fishes are one of the few evolutionary systems that provide repeated cases of adaptation to deep-sea marine environments, one of the most extreme and underexplored environments on earth. Transitions from shallow to deep-sea habitats have occurred multiple times, resulting in a variety of remarkable adaptations, from the presence of bioluminescence and small body size to a diverse array of morphological specializations. However, detailed comparative studies investigating the origin and genomic bases of specialized phenotypic novelties that have repeatedly appeared in the deep-sea continue to be poorly understood. This project aims to develop a comparative approach to study convergent morphological evolution and its underlying ecological and genomic bases in the deep-sea spikefishes (Triacanthodidae, Tetraodontiformes), which are distributed around the tropical and temperate upper slopes of the world’s oceans.Spikefishes provide an outstanding system for investigating convergent evolution as lineages in the group have independently evolved at least twice the most extreme tubular snout elongation in the Fish Tree of Life, have some of the smallest vertebrate genomes, and included well-preserved fossil species from the Eocene and Oligocene. The integration of state-of-the-art genomic and morphological data with the study of extant and fossil species will allow new ways of exploring convergent morphological evolution in a genomic and ecological framework. Moreover, understanding the determinants of deep-sea convergence at the molecular level has the potential to inform general principles of adaptation and morphological predictivity along ocean depth gradients. Overall, this project will contribute whole-genome resequencing data, CT-scans for extant and fossil taxa, and a well-resolved phylogeny of triacanthodids and allies. This project will also provide online videos, tutorials, interactive apps, museum exhibits, undergraduate and graduate training, and a series of integrative research papers exploring the links between phenotype and genotype and the associations of genomic regions involved in morphological adaptations in fishes.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.