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Osteological and genetic variation question the occurrence of three species of bottlenose dolphins (Tursiops spp.) in Australia

Jedensjö, M., Kemper, C., Allen, S., Bejder, L., Parra, G.J., Cagnazzi, D., Palmer, C. and Krützen, M. (2013) Osteological and genetic variation question the occurrence of three species of bottlenose dolphins (Tursiops spp.) in Australia. In: 20th Biennial Conference on the Biology of Marine Mammals, 9 - 13 December, Dunedin, New Zealand.

Abstract

Several species in the genus Tursiops have been described in the past. Two species have been recognized in Australian waters: T. truncatus and T. aduncus, with a third species, T. australis, recently described. We re-examined the validity of the proposed new species using the largest number of broadly distributed morphological and genetic samples of Australian Tursiops spp. to date. We carried out 2-D- (cranial measurements, shape characters, and vertebrae count) and 3-Dgeometric morphometrical analyses (73 landmarks) on 250 specimens from around Australia. Multivariate analyses (PCA, cluster, k-mean, discriminant function analyses) of skull data revealed two groups for 2-D-morphometric analyses, T. truncatus and T. aduncus. However, the separation between the two groups was not complete, as about 15% of the individuals could not be assigned to either group because of intermediate characters. In this analysis, T. australis clustered well within T. truncatus. Using 3-D geometric morphometrical characters, a principle component analysis also revealed two adjacent clusters, each showing affinity to the respective type specimen of T. truncatus and T. aduncus. In general, we found differences in overall skull shape between T. truncatus and T. aduncus. Similar to our 2-D analysis, T. australis clustered well within T. truncatus. For the genetic component of the project, we employed two genetic marker systems. Analysis of the hypervariable region I of mitochondrial DNA (n=900 soft tissue and bone/teeth samples) revealed 146 unique haplotypes. Phylogenetic reconstructions using Neighbour-Joining, Maximum Likelihood and Bayesian approaches suggested the existence of two distinct genetic clusters in Australian waters, corresponding to T. truncatus and T. aduncus. A Bayesian assignment approach using autosomal microsatellite data (n=650 soft tissue samples) also indicated the presence of two distinct groups (T. truncatus and T. aduncus), suggesting the occurrence of only two Tursiops species in Australian waters.

Publication Type: Conference Item
Murdoch Affiliation: School of Veterinary and Life Sciences
Notes: Oral presentation
URI: http://researchrepository.murdoch.edu.au/id/eprint/20221
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