title: Population differentiation and hybridisation of Australian snubfin (Orcaella heinsohni) and Indo-Pacific humpback (Sousa chinensis) dolphins in north-western 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.
authors.affiliation: Murdoch University Cetacean Research Unit, School of Veterinary and Life Sciences, Murdoch University, Perth, Western Australia, Australia.
authors.forename: Alexander M
authors.initials: AM
authors.lastname: Brown
authors.affiliation: 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.
authors.forename: Anna M
authors.initials: AM
authors.lastname: Kopps
authors.affiliation: Murdoch University Cetacean Research Unit, School of Veterinary and Life Sciences, Murdoch University, Perth, Western Australia, Australia.
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Allen
authors.affiliation: Murdoch University Cetacean Research Unit, School of Veterinary and Life Sciences, Murdoch University, Perth, Western Australia, Australia.
authors.forename: Lars
authors.initials: L
authors.lastname: Bejder
authors.affiliation: Centre for Ecology and Conservation, University of Exeter, Penryn, Cornwall, United Kingdom.
authors.forename: Bethan
authors.initials: B
authors.lastname: Littleford-Colquhoun
authors.affiliation: 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.
authors.forename: Guido J
authors.initials: GJ
authors.lastname: Parra
authors.affiliation: Marine Ecology Research Centre, School of Environment, Science and Engineering, Southern Cross University, Lismore, New South Wales, Australia.
authors.forename: Daniele
authors.initials: D
authors.lastname: Cagnazzi
authors.affiliation: Fenner School of Environment & Society, Australian National University, Canberra, Australian Capital Territory, Australia.
authors.forename: Deborah
authors.initials: D
authors.lastname: Thiele
authors.affiliation: 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.
authors.forename: Carol
authors.initials: C
authors.lastname: Palmer
authors.affiliation: GeneCology Research Centre, University of the Sunshine Coast, Maroochydore DC, Queensland, Australia.
authors.forename: Celine H
authors.initials: CH
authors.lastname: Frère
mesh_terms: D000818:Animals; D004272:DNA, Mitochondrial / Q000235:genetics; D004289:Dolphins / Q000235:genetics* / Q000502:physiology; D005260:Female; D051456:Gene Flow; D014644:Genetic Variation; D005828:Genetics, Population; D006824:Hybridization, Genetic; D008297:Male; D018895:Microsatellite Repeats; D011156:Population Density; D011157:Population Dynamics; D014904:Western Australia
chemical_list: D004272:DNA, Mitochondrial