Mitochondrial Dna Variation and Maternal Gene Flow Among Humpback Whales of the Southern Hemisphere

Abstract

Samples of skin tissue were collected by biopsy darting from humpback whales (Megaptera novaeangliae) in six seasonal habitats representing three stocks and four regions: Groups IV (western Australia), V western component (eastern Australia), V eastern component (New Zealand and Tonga) and VI (the Antarctic Peninsula and Gorgona Island, Colombia, South America) of the Southern Hemisphere. A variable section of the mitochondrial DNA control region was amplified and sequenced from 84 of these individuals, distinguishing a total of 48 unique sequences (i. e., mtDNA nucleotypes). Phylogenetic reconstructions suggested that these nucleotypes form three clades, corresponding to those previously described in a world‐wide survey of humpback whale mtDNA variation, although bootstrap support for two of the clades was relatively low (<50%). An analysis of variance adapted for molecular information showed significant differentiation of nucleotypes among the three Groups (Stocks) and heterogeneity of haplotype diversity among the four regions. A pattern of interchange within and between oceanic basins was demonstrated by the presence of shared identical nucleotypes among humpback whales in regions of the Southern and Northern Hemispheres.

Does temporal and spatial segregation explain the complex population structure of humpback whales on the coast of West Africa?

“…lee et al 2007;Palumbi and Baker 1994;Pardini et al 2001). Due to the remarkable mobility of humpback whales and the apparent absence of geographic barriers within ocean basins, the formation of significant genetic divisions between stocks indicates strong fidelity to migratory destinations, as a result of a calf's early maternally inherited experience , especially in its first year of life (Baker et al 1998). The life history of these whales suggests a likely mechanism for a 'cultural' transmission of migratory destinations (Baker et al 1990), and is supported by analysis of maternally inherited mtDna.…”

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

“…Sequences from New Caledonia (Garrigue et al 2004) were reviewed for inclusion with new sequences from the 2002 season. Most previously published sequences from Eastern Australia and New Zealand (Baker et al 1998) were not included in this analysis because of the small sample size from these areas. One sample from Eastern Australia (EA11) was re-sequenced for inclusion because of its unusual position in an earlier phylogenetic analysis (Baker et al 1998).…”

Organismal and 'gametic' capture-recapture using microsatellite genotyping confirm low abundance and reproductive autonomy of humpback whales on the wintering grounds of New Caledonia

“…New Caledonia to Tonga), but this level of interchange is low when compared to interannual return, suggesting fidelity to individual wintering grounds. A comparison of mitochondrial (mt) DNA differentiation has confirmed a degree of genetic isolation of Oceania from wintering grounds near Colombian (presumed Group I) and Western Australia (presumed Group IV), but sample sizes were not sufficient to evaluate isolation among regions within Oceania (Baker et al 1998). However, differences in reported rates of recovery in eastern Australia and Oceania suggest demographic independence of these regions.…”