Genetic population structure of the round whitefish (Prosopium cylindraceum) in North America: multiple markers reveal glacial refugia and regional subdivision

Round whitefish (Prosopium cylindraceum) have abroad, disjunct range across northern North America and Eurasia, and little is known about their genetic population structure. We performed genetic analyses of round whitefish from 17 sites across its range using nine microsatellites, two mitochondrial DNA (mtDNA) loci, and 4918 to 8835 single-nucleotide polymorphism (SNP) loci. Our analyses identified deep phylogenetic division between eastern and western portions of the range, likely indicative of origins from at least two separate Pleistocene glacial refugia. Regionally, microsatellites and SNPs identified congruent patterns in subdivision, and population structure was consistent with expectations based on hydrologic connectivity. Within the Laurentian Great Lakes, Lake Huron and Lake Ontario were identified as key areas of interest. Lake Huron appears to be a contemporary source population for several other Great Lakes, and Lake Ontario contains a genetically discrete group of round whitefish. In all cases, multiple genetic markers yielded similar patterns, but SNPs offered substantially enhanced resolution. We conclude that round whitefish have population subdivision on several scales important for understanding their evolutionary history and conservation planning. Les menominis ronds (Prosopium cylindraceum) ont une vaste aire de repartition discontinue dans le nord de l'Amerique du Nord et l'Eurasie, et les connaissances sur la structure genetique de leurs populations sont tres limitees. Nous avons realise des analyses genetiques de menominis ronds de 17 emplacements a la grandeur de leur aire en utilisant neuf microsatellites, deux sites d'ADN mitochondrial (ADNmt) et de 4918 a 8835 sites de polymorphisme mononucleotidique (SNP). Nos analyses font ressortir une division phylogenetique profonde entre les portions orientale et occidentale de l'aire de repartition, qui indique vraisemblablement des origines remontant a au moins deux refuges glaciaires pleistocenes distincts. A l'echelle regionale, les microsatellites et les SNPs font ressortir des motifs de subdivision congruents, et la structure des populations obtenue concorde avec les previsions basees sur la connectivite hydrologique. Il est etabli que, au sein des Grands Lacs laurentiens, les lacs Huron et Ontario constituent des regions d'interet. La population du lac Huron semble etre une population source contemporaine pour plusieurs autres Grands Lacs, et le lac Ontario renferme un groupe de menominis ronds distinct sur le plan genetique. Dans tous les cas, plusieurs marqueurs genetiques produisent des motifs semblables, mais les SNP offrent une resolution nettement accrue. Nous en concluons que les populations de menominis ronds sont subdivisees a plusieurs echelles importantes pour la comprehension de leur evolution et la planification de leur conservation. [Traduit par la Redaction]
Introduction The round whitefish (Salmonidae; Coregoninae; Prosopium cylindraceum) is a widespread species that has become a conservation concern in several regions of North America. In the northeastern United States, several [...]