Population differentiation and hybridisation of Australian snubfin (Orcaella heinsohni) and Indo-Pacific humpback (Sousa chinensis) dolphins in north-western Australia

Alexander M Brown; Anna M Kopps; Simon J Allen; Lars Bejder; Bethan Littleford-Colquhoun; Guido J Parra; Daniele Cagnazzi; Deborah Thiele; Carol Palmer; Celine H Frère

doi:10.1371/journal.pone.0101427

Population differentiation and hybridisation of Australian snubfin (Orcaella heinsohni) and Indo-Pacific humpback (Sousa chinensis) dolphins in north-western Australia

PLoS One. 2014 Jul 2;9(7):e101427. doi: 10.1371/journal.pone.0101427. eCollection 2014.

Authors

Affiliations

¹ Murdoch University Cetacean Research Unit, School of Veterinary and Life Sciences, Murdoch University, Perth, Western Australia, Australia.
² Centre for Ecology and Conservation, University of Exeter, Penryn, Cornwall, United Kingdom; Marine Evolution and Conservation, Centre for Ecological and Evolutionary Studies, University of Groningen, Groningen, The Netherlands.
³ Centre for Ecology and Conservation, University of Exeter, Penryn, Cornwall, United Kingdom.
⁴ Cetacean Ecology, Behaviour and Evolution Lab, School of Biological Sciences, Flinders University, Adelaide, South Australia, Australia; South Australian Research and Development Institute, Adelaide, South Australia, Australia.
⁵ Marine Ecology Research Centre, School of Environment, Science and Engineering, Southern Cross University, Lismore, New South Wales, Australia.
⁶ Fenner School of Environment & Society, Australian National University, Canberra, Australian Capital Territory, Australia.
⁷ Marine Ecosystems, Flora and Fauna Division, Department of Land Resource Management, Palmerston, Northern Territory, Australia; Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, Northern Territory, Australia.
⁸ GeneCology Research Centre, University of the Sunshine Coast, Maroochydore DC, Queensland, Australia.

Abstract

Little is known about the Australian snubfin (Orcaella heinsohni) and Indo-Pacific humpback (Sousa chinensis) dolphins ('snubfin' and 'humpback dolphins', hereafter) of north-western Australia. While both species are listed as 'near threatened' by the IUCN, data deficiencies are impeding rigorous assessment of their conservation status across Australia. Understanding the genetic structure of populations, including levels of gene flow among populations, is important for the assessment of conservation status and the effective management of a species. Using nuclear and mitochondrial DNA markers, we assessed population genetic diversity and differentiation between snubfin dolphins from Cygnet (n = 32) and Roebuck Bays (n = 25), and humpback dolphins from the Dampier Archipelago (n = 19) and the North West Cape (n = 18). All sampling locations were separated by geographic distances >200 km. For each species, we found significant genetic differentiation between sampling locations based on 12 (for snubfin dolphins) and 13 (for humpback dolphins) microsatellite loci (FST = 0.05-0.09; P<0.001) and a 422 bp sequence of the mitochondrial control region (FST = 0.50-0.70; P<0.001). The estimated proportion of migrants in a population ranged from 0.01 (95% CI 0.00-0.06) to 0.13 (0.03-0.24). These are the first estimates of genetic diversity and differentiation for snubfin and humpback dolphins in Western Australia, providing valuable information towards the assessment of their conservation status in this rapidly developing region. Our results suggest that north-western Australian snubfin and humpback dolphins may exist as metapopulations of small, largely isolated population fragments, and should be managed accordingly. Management plans should seek to maintain effective population size and gene flow. Additionally, while interactions of a socio-sexual nature between these two species have been observed previously, here we provide strong evidence for the first documented case of hybridisation between a female snubfin dolphin and a male humpback dolphin.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
DNA, Mitochondrial / genetics
Dolphins / genetics*
Dolphins / physiology
Female
Gene Flow
Genetic Variation
Genetics, Population
Hybridization, Genetic
Male
Microsatellite Repeats
Population Density
Population Dynamics
Western Australia

Substances

DNA, Mitochondrial

Grants and funding

The Australian Marine Mammal Centre funded this research (2008–09/19, 2009/19 and 2011/23). Alex Brown was the recipient of a Murdoch University International Postgraduate Scholarship. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.