Phylogeny, Biogeography, and Taxonomy of Australasian Teals

Abstract

Abstract The taxonomy of the Australasian teals has been particularly unstable. Australasian Grey Teal (Anas gracilis) and Chestnut Teal (A. castanea) are widely viewed as specifically distinct, but the taxonomy of the New Zealand teals remains unsettled. Because conservation status is affected by taxonomic rank, it is important to resolve the status of the rare subantarctic teals. To estimate phylogenetic relationships of teals, we sequenced three mitochondrial DNA genes (12S, and ATPase 6 and 8). The resultant phylogeny unequivocally groups the Chestnut Teal with the Grey Teal, rather than with the New Zealand teals as has traditionally been held (Fleming 1953). A greater level of sequence divergence occurred within the New Zealand teals than between the Grey and Chestnut teals. This diversity, together with morphological and behavioral differences, implies that the New Zealand teals should be accorded specific status as A. aucklandica, A. nesiotis, and A. chlorotis. Although it is most likely that the teal that colonized the Auckland Islands and Campbell Islands originated in New Zealand, our data do not allow us to determine whether the ancestors of the Campbell Island Teal came from mainland New Zealand or the Auckland Islands. This uncertainty arises because, as our data show, the colonization events were separated by a short period of time.