Testing for the stages of vertebrate radiation using freshwater fishes of the family Percidae

Middle Tennessee State University, Murfreesboro TN

Investigators

Abstract

Understanding why some groups of organisms are made up of species of many different shapes and sizes, while others are not, is a key goal of evolutionary biology. Does morphological diversity arise in a sudden burst of evolution, or does it accumulate gradually? The gradual model of adaptive radiation hypothesizes that organisms first diversify in traits to explore new habitats, then to feed on different resources, and lastly to communicate reproductive fitness. However, few rigorous quantitative tests of this model have been performed, and mostly on unique, island-based radiations. This project will test this model of diversification using the family Percidae (e.g., perches, walleye and darters), one of the most diverse families of freshwater fishes in the USA. This research will use advanced 3D imaging techniques to create a comprehensive database of traits linked to habitat, diet and communication and analyses to better understand how and when these traits evolved during the history of Percidae. This work will also expand an open access digital library of fish anatomical diversity, contribute to local ichthyology courses, expand a Natural History Center’s aquatic exhibit space, and train undergraduate and graduate students in fish biology, evolution and statistical programming. This project seeks to test Streelman and Danley’s “three stages of vertebrate radiation” using rigorous phylogenetic comparative methods and comprehensive datasets of ecologically-linked phenotypic characters within percid fishes. The project will use non-destructive 3D imaging (e.g., laser scanning, micro-CT, dice-CT) of field-collected and museum-preserved specimens, including extensive taxonomic sampling across the family Percidae. Phylogenetic comparative methods will be used to test for peaks in the diversification of these trait complexes using a newly published all-Percid phylogeny. The researchers will investigate how the evolutionary lability of these trait axes has been impacted by intrinsic mechanisms such as allometry, modularity or biomechanical/constructional constraints, and whether this contributes to a hierarchical pattern of trait evolution. Lastly, the researchers will test for an association between each trait axis and speciation rates. This work will help to elucidate the macroevolutionary drivers of biodiversity, and enhance our understanding of the contributions of selection and adaptation to trait diversity. 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.