MITOCHONDRIAL-DNA VARIATION AND MATERNAL GENE FLOW AMONG HUMPBACK WHALES OF THE SOUTHERN-HEMISPHERE

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 wester n component (eastern Australia), V eastern component (New Zealand and Tonga) and VI (the Antarctic Peninsula and Gorgona Island, Colombia, S outh America) of the Southern Hemisphere. A variable section of the mi tochondrial 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 thes e nucleotypes form three clades, corresponding to those previously des cribed in a world-wide survey of humpback whale mtDNA variation, altho ugh bootstrap support for two of the clades was relatively low (<50%). An analysis of variance adapted for molecular information showed sign ificant differentiation of nucleotypes among the three Groups (Stocks) and heterogeneity of haplotype diversity among the four regions. A pa ttern of interchange within and between oceanic basins was demonstrate d by the presence of shared identical nucleotypes among humpback whale s in regions of the Southern and Northern Hemispheres.