Fish diversity spans high-performance swimmers such as tunas, barracudas, and swordfish that spend their entire life cruising the open ocean in search of food (pelagic species) to sluggish, sedentary forms such as flounders or seahorses that live buried in the bottom or attached to vegetation (benthic species). Much variation in body form and habit can be explained by adaptation to the habitats where these fishes live. But the effects of ecological habitat on processes leading to diversification over evolutionary time remain poorly explored. This project will focus on two groups of closely related species that harbor a huge diversity of benthic and pelagic forms (about 2000 species) to disentangle the effects of habitat transitions on rates of speciation and extinction. Understanding the factors that promote diversification in form and habit is important for the long-term conservation of marine biodiversity. Innovative image data analysis necessary to synthesize morphological variation among these fishes also will be applied to develop a fish species identification app for smartphones (FishSnap) that will be freely available to the public, expandable in the future to include all fishes. Educational opportunities will be available for undergraduate and graduate students and outreach activities in partnership with the National Museum of Natural History in Washington DC will result in a new public exhibit on fish biodiversity.
Recent studies in fish phylogenetics are resolving long-lasting uncertainties about the relationships among the most species-rich marine fish groups, and opening up unprecedented opportunities to infer mechanisms that explain their extraordinary diversity. This project takes advantage of newly discovered affinities among fishes that revealed two independent clades with benthic and pelagic forms to investigate connections between genomic and morphological features in relation to their ecological habitat. The researchers will collect and compare a genome-scale DNA sequence data set of protein-coding genes to infer a phylogenetic tree for about 800 species of these two groups. This tree will be time-calibrated on the basis of carefully selected fossil data to provide a dated evolutionary framework for comparative studies. The project will also assemble a large phenotypic (digital image) dataset of curated specimens for morphometric analysis. Using state-of-the art comparative methodologies, this project will shed light on the effect of habitat shifts along the benthic-pelagic axis on the rate of morphological and lineage diversification. The integration of well-resolved molecular phylogenies, the fossil record, trait and ecological data, and comparative methodologies will provide new insights to understand the causes of marine biodiversity.
