Influence of seasonal migration on geographic distribution of mitochondrial DNA haplotypes in humpback whales

Abstract

Humpback whales (Megaptera novaeangliae) migrate nearly 10,000 km each year between summer feeding grounds in temperate or near-polar waters and winter breeding grounds in shallow tropical waters. Observations of marked individuals suggest that major oceanic populations of humpback whales are divided into a number of distinct seasonal subpopulations which are not separated by obvious geographic barriers. To test whether these observed patterns of distribution and migration are reflected in the genetic structure of populations, we looked for variation in the mitochondrial DNA of 84 individual humpback whales on different feeding and wintering grounds of the North Pacific and western North Atlantic oceans. On the basis of restriction-fragment analysis, we now report a marked segregation of mitochondrial DNA haplotypes among subpopulations as well as between the two oceans. We interpret this segregation to be the consequence of maternally directed fidelity to migratory destinations.

Genetic differentiation between sympatric Killer whale populations

“…This is about five times the variation seen in the Killer whale D-loop. However, the average genetic distance between whole mtDNA genomes derived from intraspecific, interpopulation comparisons of humpback whales (Megaptera novaengliae) (average of 2.6 x 10-s substitutions per nucleotide; Baker et al, 1990) is closer to the Killer whale genetic distances. These comparisons are relevant because the substitution rate in the cetacean D-loop is roughly equivalent to the whole mtDNA genome rate in cetaceans and other mammalian taxa (Hoelzel, 1989).…”

Population structure of South Pacific humpback whales and the origin of the eastern Polynesian breeding grounds

“…The relative isolation of the Colombian breeding ground is consistent with the lack of observed individual interchange with Oceania and western South Atlantic, based on comparison of photo-identified whales (Garrigue et al 2002, Stevick et al 2004. The genetic distinctiveness of the Colombian subpopulation could be related, in part, to the influence of historic or ongoing trans-equatorial gene flow thought to occur along the Pacific coast of central America (Baker et al 1990, Caballero et al 2001, Medrano-González et al 2001.…”

Sex–biased dispersal in sperm whales: contrasting mitochondrial and nuclear genetic structure of global populations

“…Among baleen whales, minke whales (Hoelzel & Dover 1991;van Pijlen et al 1995), humpback whales (Baker et al 1990(Baker et al , 1993Palumbi & Baker 1994;Valsecchi et al 1997) and ¢n whales (Be¨rube¨et al 1998) all show substantially higher mtDNA diversity and strong di¡erentiation in both mtDNA and nuclear DNA markers between and, in some cases, within oceans. In humpback whales, seasonal migrations between high-latitude feeding and low-latitude breeding grounds have been shown to involve strong ¢delity to migratory destinations (Baker et al 1986;Clapham et al 1993).…”