Analysis of mitochondrial DNA clarifies the taxonomy and distribution of the Australian snubfin dolphin (Orcaella heinsohni) in northern Australian waters

Abstract

Conservation management relies on being able to identify and describe species. Recent morphological and molecular analyses of the dolphin genus Orcaella show a species-level disjunction between eastern Australia and South-east Asia. However, because of restricted sampling, the taxonomic affinities of the geographically intermediate populations in the Northern Territory and Western Australia remained uncertain. We sequenced 403 base pairs of the mitochondrial control region from five free-ranging Orcaella individuals sampled from north-western Western Australia and the Northern Territory. Low net nucleotide divergence (0.11–0.67%) among the Australian Orcaella populations show that populations occurring in the Northern Territory and Western Australia belong to the Australian snubfin (O. heinsohni) rather than the Asian Irrawaddy dolphin (O. brevirostris). Clarifying the distribution of Orcaella is an important first step in the conservation and management for both species; however, an understanding of the metapopulation structure and patterns of dispersal among populations is now needed.