Are Hypomesus chishimaensis and H. nipponensis (Osmeridae) Distinct Species? A Molecular Assessment Using Comparative Sequence Data from Five Genes
We used mitochondrial (cytb, 16S) and nuclear (ITS2, S71, RAG1) sequence data to assess the degree of genetic differentiation between the recently described lacustrine Hypomesus chishimaensis from the Kuril Islands and its anadromous congener H. nipponensis from Hokkaido, Japan. The results showed that the two species are not genetically distinct at these loci. Phylogenetic trees depicted an unstructured clade consisting of individuals of both species and sequence data showed haplotypes that are shared between putative species for all markers. We conclude that H. chishimaensis is an alternative life-history type of H. nipponensis that should not be recognized at either the species or the sub-species level.Abstract
Sample locations of Hypomesus chishimaensis (•), H. nipponensis (○), and H. olidus (*).
Combined mitochondrial (cytb and 16S) and nuclear (ITS2, S71, and RAG1) phylogeny of Hypomesus chishimaensis, H. nipponensis, and H. olidus, with outgroup Mallotus villosus based on a GTR + I model of sequence evolution.
Numbers following taxon names identify the individual fish used for the final analyses (see Results). The number above the H. chishimaensis/H. nipponensis node represents the ML bootstrap value (n = 1,000), while that below the node represents the Bayesian posterior probability (%; 45,000 trees). Scale bar represents ten changes.
Contributor Notes
Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver, BC, V6T 1Z4, Canada. E-mail: (KLI) ilves@zoology.ubc.ca. Send reprint requests to KLI.