Gene flow and species delimitation in fishes of Western North America: Flannelmouth (Catostomus latipinnis) and Bluehead sucker (C. Pantosteus discobolus). Issue 13 (17th June 2020)

• Record Type: Journal Article
• Authors: Bangs, Max R.; Douglas, Marlis R.; Chafin, Tyler K.; Douglas, Michael E.
• Is Part Of: Ecology and evolution. Volume 10:Issue 13(2020)
• Page Start: 6477
• Page End: 6493
• Publication Date: 2020-06-17
• Subjects: Catostomus -- ddRAD -- hybridization -- introgression -- phylogenomics -- species delimitation; Ecology -- Periodicals; Evolution -- Periodicals; 577.05
• DOI: 10.1002/ece3.6384
• Languages: English
• ISSNs: 2045-7758

Abstract

Abstract: The delimitation of species boundaries, particularly those obscured by reticulation, is a critical step in contemporary biodiversity assessment. It is especially relevant for conservation and management of indigenous fishes in western North America, represented herein by two species with dissimilar life histories codistributed in the highly modified Colorado River (i.e., flannelmouth sucker, Catostomus latipinnis ; bluehead sucker, C. (Pantosteus) discobolus ). To quantify phylogenomic patterns and examine proposed taxonomic revisions, we first employed double‐digest restriction site‐associated DNA sequencing (ddRAD), yielding 39, 755 unlinked SNPs across 139 samples. These were subsequently evaluated with multiple analytical approaches and by contrasting life history data. Three phylogenetic methods and a Bayesian assignment test highlighted similar phylogenomic patterns in each, but with considerable difference in presumed times of divergence. Three lineages were detected in bluehead sucker, supporting elevation of C. (P.) virescens to species status and recognizing C. (P.) discobolus yarrowi (Zuni bluehead sucker) as a discrete entity. Admixture in the latter necessitated a reevaluation of its contemporary and historic distributions, underscoring how biodiversity identification can be confounded by complex evolutionary histories. In addition, we defined three separate flannelmouth sucker lineages as ESUs (evolutionarily significant units), given limited phenotypic and genetic differentiation, contemporary isolation, and lack of concordance (per the genealogical concordance component of the phylogenetic species concept). Introgression was diagnosed in both species, with the Little Colorado and Virgin rivers in particular. Our diagnostic methods, and the agreement of our SNPs with previous morphological, enzymatic, and mitochondrial work, allowed us to partition complex evolutionary histories into requisite components, such as isolation versus secondary contact. Abstract : Phylogenomic patterns and proposed taxonomic revisions were examined in two species with dissimilar life histories codistributed in the highly modified Colorado River, the flannelmouth sucker ( Catostomus latipinnis ) and the bluehead sucker ( C. Pantosteus discobolus ). We utilized ddRAD along with several phylogenetic, population genetic, and species delimitation approaches to examine the phylogeny, detect hybridization, and introgression, and test proposed taxonomic revision. Our diagnostic methods, and the alignment of our SNPs with previous morphological, enzymatic, and mitochondrial work, allowed us to partition complex evolutionary histories into requisite components, such as isolation versus secondary contact.