Matriarchal genetic population structure of North American beluga whales Delphinapterus leucas (Cetacea: Monodontidae)

Abstract

The North American beluga whale Delphinapterus leucas population has been divided into a number of putative geographical stocks based upon migration routes and areas of summer concentration. Nucleotide sequences of the mitochondrial DNA (mtDNA) control region were used to assess whether these geographical stocks are genetically distinct. Beluga whale samples from 25 sites were collected primarily from aboriginal subsistence hunts across North America from 1984 to 1994. Thirty-nine mtDNA haplotypes were identified in 628 beluga samples. No differences were found in the distribution of haplotypes between male and female beluga whales at any sampling site. These haplotypes segregated into two distinct assemblages in both a haplotype network and a neighbour-joining tree. The haplotype assemblages and a geographically disjunct distribution that suggests postglacial recolonization of the North American Arctic from two different refugia. An analysis of molecular variance based on haplotype relationships and frequency indicated genetic heterogeneity among beluga whale summering groups (P < or = 0.001). Sequence divergence estimates between sampling sites also indicated geographical differentiation, particularly between samples taken at east Hudson Bay or St Lawrence River and the western or central Arctic. The results of this study show a high degree of philopatry to specific summering areas by this highly mobile animal.

Climate Change and the Molecular Ecology of Arctic Marine Mammals

“…The rate at which different regions of the genome mutate, their mode of inheritance, and whether they are under selection or not provide a potentially endless supply of genetic tools applicable to a wide range of -Gladden et al (1997-Gladden et al ( , 1999, deMarch and Postma (2003) 5 0.71 Brown-Gladden et al (1997) 5, 15 0.76, 0.66 Brown-Gladden et al (1997, deMarch and Postma (2003) questions in wildlife ecology. This paper will focus on studies that used markers that are believed to be under weak or no selection.…”

“…Although telemetry studies indicate that Arctic cetaceans possess long-distance dispersive capabilities (Suydam et al 2001, Laidre et al 2008), analyses of patterns of variation within mtDNA have demonstrated strong maternally directed philopatry to traditional summering grounds in beluga whales, Delphinapterus leucas (see Plate 1) (Brennin et al 1997, Brown Gladden et al 1997, deMarch and Postma 2003 Table 2) and narwhals, Monodon monoceros (Palsbøll et al 1997a). This tendency to return to the same locations generation after generation is likely driven by the predictable availability of resources, with the result that these summering concentrations eventually become demographically discrete populations.…”

“…Over the past two decades this phylogeographic approach (sensu Avise et al 1987) has illuminated the species and population histories of many high-latitude organisms (e.g., Bernatchez and Wilson 1998, Weider and Hobaek 2000, Stamford and Taylor 2004, including marine mammals. The star-like phylogenies of mtDNA lineages observed in beluga whales and the substantial phylogeographic partitioning of these lineages today argue that the origins of separate summering concentrations date back to postglacial expansion from refugial populations and indicate limited dispersal among these summering groups for long periods (Brennin et al 1997, Brown Gladden et al 1997. In some cases (e.g., Cook Inlet, Gulf of St. Lawrence) the genetic evidence indicated isolation of populations over evolutionary timescales.…”

Socio-sexual and probable mating behavior of Cook Inlet beluga whales, Delphinapterus leucas, observed from an aircraft

“…This would suggest mating occurs in early spring. In autumn, beluga whale populations migrate toward a few common wintering grounds in Bering Sea offshore waters characterized by unconsolidated pack ice where mating is believed to occur during late winter or early spring (Brodie, 1971;Sergeant, 1973;Brown Gladden et al, 1997).…”

Population genetic structure of the ascidian Styela rustica at Kongsfjorden, Svalbard, Arctic

“…A growing interest on population genetic structure surveys at different scales in the Arctic has been evident in the last decade. Most of the work in the marine realm was devoted to fishes and mammals (Wilson et al, 1996;Brown-Gladden et al, 1997;Paetkau et al, 1999;Weider and Hobaek, 2000, and others). Terrestrial plants, invertebrates, birds and mammals have been the focus of several works as well (Tollefsrud et al, 1998;Holder et al, 1999;Ehrich et al, 2000).…”