BURRUNAN DOLPHIN GENETIC FINGERPRINTING

There’s so much we still don’t know about the endangered Burrunan dolphins, much of this is because they spend so much time underwater making it difficult to answer questions like:

• Are the males that show long-term relationship related?

• Who are our successful Mums?

• Being such a small and isolated population, are they inbred?

• Do the two populations mix?

• Are there any hybrids between the other bottlenose species?

• Being the most ancestral node for all bottlenose dolphins worldwide, the split dated at over 1 million years (Moura et al. 2013)… how did this species come to be?

By looking at the dolphin’s DNA we can answer these questions…and so much more!

CONSERVATION CONCERN

In 2011, Principal Researcher and Founding Director of the Marine Mammal Foundation (MMF), Dr Kate Robb, formally identified and named Tursiops australis, known commonly as ‘Burrunan dolphin’ following Australian aboriginal narrative (Charlton-Robb et al. 2011). The Burrunan dolphin has already been listed as ‘Threatened’ under the Victorian State Flora and Fauna Guarantee Act due to its small and isolated populations. In accordance with the International Union for Conservation of Nature (IUCN) Red List and the Australian Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act), the Burrunan dolphin would be classified as ‘data deficient’.

Dr Kate’s previous genetic work has highlighted that the Burrunan dolphin is characterised by small and genetically isolated populations, with effective populations sizes of only 65 for the Gippsland Lakes and and 82 for Port Phillip Bay (Charlton-Robb et al. 2015). This population has significant conservation concern due to their low levels of genetic diversity, close proximity to urban and residential settings and high exposure to various anthropogenic threats.

SO WHAT’S THIS ALL ABOUT?

Dr Kate began her genetic research back in 2006, during this time there has been some dramatic changes with the development of new technologies that allow us to look at the entire genome, rather than small fragments of the DNA sequence. Adding to this is the taxonomic complexity of Tursiops species (bottlenose dolphins). With upwards of 20 species historically described, there are now only three species are now recognised, including our very own Burrunan dolphin! Recent recommendations have been made for the inclusions of nuclear data as a priority to assess the taxonomic affinities and conservation of Tursiops species. Genome-wide assessment using single nucleotide polymorphisms (SNPs) is fast becoming useful in evolution, ecology, and conservation applications.

Dr Kate and Dr Amy Adams have, for the first time in Australia, used a new technique to isolate over 11,840 SNPs across the genome specific to dolphins. This newer technology was developed as a pilot study with a limited number of dolphin samples.

They recently presented this research on the world stage and received a huge amount of interest, including from the Smithsonian! They are now taking this incredible research to the next level and aim to genetically profile Burrunan dolphins from our two resident population, and incorporate other Tursiops samples from across the globe and not only assess our local dolphins but place them in world-wide context!

By extracting the full dolphin genome we are able to genetically sex the individuals, assess who is related to whom and place this in their socially complex structure, assess the calving success of the females, assess the levels of migration between the populations, assess levels of inbreeding, and importantly address the conservation status required for national and international conservation effort.

HOW CAN YOU HELP?

If you would like to help us get on the water and continue to conduct our research, consider a donation! As a small not-for-profit organisation, every little bit goes a long way.

By donating $50 to this campaign we will be able to genetically profile each of our iconic Burrunan dolphins, including genetic sexing, mtDNA sequencing and genome assessments. Not only genetically fingerprinting each dolphin but placing in a global perspective.

$50 allows us to genetically profile ONE dolphin….so a donation of $200 allows us to genetically profile FOUR dolphins, $1000 allows us to genetically profile TWENTY dolphins!

PUBLICATIONS

Charlton-Robb, K., Taylor, A.C., McKechnie, S.W. (2016) Population genetic structure of the Burrunan dolphin (Tursiops australis) in coastal waters of south-eastern Australia: conservation implications. Conservation Genetics. DOI 10.1007/s10592-014-0652-6

Abstract:

The Burrunan dolphin, Tursiops australis, is a newly described species endemic to southern Australian coastal waters. The current distribution ranges from South Australia, east to Victoria and south to Tasmania. In the eastern region of their range, only two known resident populations of T. australis occur, Port Phillip Bay and the Gippsland Lakes. Little else is known about the population status and migration patterns of the species. Here we examine population genetics of T. australis using ten microsatellite loci and two sequences of mitochondrial DNA, the control region (~450 bp) and cytochrome b (~1,200 bp). A total of 163 T. australis samples were collected from various locations across the Victorian and Tasmanian coastlines. Genetic data showed the highest differentiation between the Port Phillip Bay and both Gippsland Lakes and Tasmanian samples. Network analysis, using concatenated mtDNA sequences, showed geographic segregation and Bayesian analysis, using microsatellite data, also supported the presence of two genetic clusters. Both microsatellite and mtDNA data indicated low genetic diversity when compared to levels reported for other dolphins. Maternal philopatry was suggested for Port Phillip Bay in particular. Our data suggest that T. australis from coastal waters of south-eastern Australia consists of two populations with little or no contemporary gene flow; one occurs in Port Phillip Bay; the second extends from the east coast of Tasmania across Bass Strait to Gippsland Lakes. Tursiops australis appears to be characterised by small, localised, genetically distinct populations and should thus be further assessed under local, national and international threatened species criteria.

Moller, L., Bilgmann, K., Charlton-Robb, K., Beheregaray, L. (2008) Multi-gene evidence for a new bottlenose dolphin species in southern Australia. Molecular Phylogenetics and Evolution 49:674-681.

Charlton, K., Taylor, A.C., McKechnie, S.W. (2006) A note on divergent mtDNA lineages of “bottlenose” dolphins from coastal waters of southern Australia. J. Cetacean Res. Manage 8(2), 173-179.

Presentations

Charlton-Robb, K. and Adams, A. (2017) A whole genome DArTseq and SNP analysis approach for the assessment of phylogenetic affinities and population differentiation of Tursiops species. Oral presentation. 22nd Biennial Conference on the Biology of Marine Mammals. Halifax, Canada.