Phenotypic and genetic differentiation of two major phylogeographical lineages of arctic grayling Thymallus arcticus in the Lena River, and surrounding Arctic drainages |
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| Authors: | STEVEN WEISS IGOR KNIZHIN ALEXANDER KIRILLOV ELSA FROUFE |
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| Institution: | Karl-Franzens University Graz, Institute of Zoology, Universitätsplatz 2, A-8010 Graz, Austria; Irkutsk State University, Biological Faculty, ul K. Marksa 1, Irkutsk 664003, Russia; Institute of Applied Ecology of the North, AS RS (Ya), Yakutia, Russia; CIBIO/UP, Campus Agrário de Vairão, 4480-661, Vairão, Portugal; Faculdade de Ciências, Universidade do Porto, Praça Gomes Teixeira, 4000-002 Porto, Portugal |
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| Abstract: | Two phylogeographical lineages of arctic grayling, Thymallus arcticus , in Siberia are extensively characterized based on both molecular genetic (mtDNA control region sequences) and phenotypic (12 meristic characters) data. One lineage, occurring in the delta region of the Lena River as well as all other Arctic draining rivers sampled, corresponds to the subspecific taxon Thymallus arcticus pallasii , whose type locality is the Kolyma River. This taxon is proposed to be a postglacial colonizer of the Lena delta. The second lineage occurs throughout the rest of the Lena basin and is proposed to have survived in a glacial refugium in the middle reaches of the Lena. These lineages form reciprocally monophyletic groups based on mtDNA sequences (net divergence 3.2%), a relationship that is concordant with phenotypic data, and thus reflects distinct taxa. The upper Lena taxon is given the preliminary name of Thymallus arcticus lenensis . Phylogenetic analysis, together with previously published data from North America, reveals that mtDNA sequences from North American populations group within the diverse clade corresponding to T. a. pallasii in Siberia. Despite the relatively close genetic relationship of most North American haplotypes with those in northern Siberia, inferences of fragmentation between the continents are supported, but bidirectional movements between the two continents are seen as likely. Despite inclusion in the clade representing T. a. pallasii in Siberia, the source of the relatively divergent Nahanni refuge haplotypes in North America is not resolved. Otherwise, inferences of postglacial expansion across several thousand kilometres are well supported within North America, but only smaller-scale colonization events among drainages are supported in Siberia. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 88 , 511–525. |
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| Keywords: | lenensis morphology mtDNA pallasii |
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