Population differentiation and hybridisation of Australian snubfin and Indo-Pacific humpback dolphins in north-western Australia
Kopps, A.M., Brown, A., Littleford-Coquhoun, B., Allen, S., Bejder, L., Thiele, D., Parra, G. and Frère, C. (2013) Population differentiation and hybridisation of Australian snubfin and Indo-Pacific humpback dolphins in north-western Australia. In: 20th Biennial Conference on the Biology of Marine Mammals, 9 - 13 December, Dunedin, New Zealand.
Little is known about Indo-Pacific humpback (Sousa chinensis) and Australian snubfin (Orcaella heinsohni) dolphins. Both species are considered sympatric throughout north western Australia, a region that is currently experiencing extensive habitat modification through coastal development. We conducted a pilot study to assess genetic diversity and differentiation between snubfin dolphins from Cygnet Bay and Roebuck Bay, as well as among Indo-Pacific humpback dolphins from Cygnet Bay, the Dampier Archipelago and Exmouth. In total, we took biopsy samples of 40 Indo-Pacific humpback dolphins and 49 snubfin dolphins. Not surprisingly given the geographic distances of >200 km between populations, we found significant genetic differentiation among all within species population comparisons based on 15 microsatellite loci (FST = 0.1-0.3; P < 0.01) and a 422 bp sequence of the mitochondrial control region (FST = 0.35-0.75; P < 0.01). These are the first estimates of genetic diversity and differentiation for snubfin and humpback dolphins in Western Australia, providing valuable information upon which to assess their conservation status within this region. However, more samples are required for an accurate estimate of population connectivity. Until then, population management agencies should treat these populations as independent management units. Additionally, genetic analyses were conducted on a sample from an adult individual at Cygnet Bay which exhibited phenotypic characteristics of both Indo-Pacific humpback dolphin and a snubfin dolphin. Mitochondrial control-region sequences and microsatellite analyses including Indo-Pacific humpback, snubfin, and bottlenose (Tursiops aduncus) dolphin samples from Cygnet Bay confirmed that this female individual is most certainly a hybrid cross between a snubfin dolphin female and an Indo-Pacific humpback dolphin male. No evidence of hybridisation was found in any other samples. While interactions of a socio-sexual nature between these two species have been observed previously, this is the first reported hybridisation.
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|Murdoch Affiliation:||School of Veterinary and Life Sciences|
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