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Data from: The role of ecology in allopatric speciation of darters in the Central Highlands, USA

Stokes, Maya F.1; Harrington, Richard2; Kim, Daemin3; Westhoff, Jacob T.4; Berkman, Leah K.5; Taylor, Adam6; Quinn, Jeffrey W.7; Near, Thomas J.6

Published Nov 24, 2025 on Dryad. https://doi.org/10.5061/dryad.stqjq2cfv

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Nov 24, 2025 version files 25.86 MB

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Abstract

Allopatric speciation is the predominant mode of speciation in riverine fishes. However, the relative importance of genetic drift versus natural selection in the allopatric speciation of these fishes remains uncertain. Here, we present a case study that demonstrates the role of ecology in the diversification of a group of imperiled freshwater fishes from the central United States. We integrate a phylogenomic dataset with analyses of streamwise distance, environmental variables, meristic and morphological traits, and diet to investigate the ecological context and outcomes of allopatric speciation within a species complex comprising the Slenderhead Darter Percina phoxocephala (Nelson), Ouachita Darter Percina brucethompsoni (Robison, Cashner, and Near), and Longnose Darter Percina nasuta (Bailey). We find that two of the species traditionally delimited based on disparity in snout length, P. phoxocephala and P. nasuta, are polyphyletic, revealing three instances of the parallel evolution of snout length disparity. We propose a revised taxonomy including the delimitation of six new species based on disparity in phenotypic traits and phylogenomic analyses. We find that morphological differences are not correlated with genetic divergence but are congruent with with variations in diet and environmental niches, suggesting a role for ecological factors in allopatric speciation of riverine fishes. The resources associated with this manuscript include genomic data, phylogenetic analyses, genomic analyses, morphological measurements of museum specimens, gut contents from museum specimens, and geospatial analyses of publically available environmental variables.