Phylogeography of the endemic New Zealand tree Entelea arborescens (whau; Malvaceae)

We investigated the phylogeography of the New Zealand endemic monotypic coastal tree Entelea arborescens (whau; Malvaceae). The distribution of whau in the southern North Island and South Island has been suggested to result from pre-European Māori cultivation. Whau wood is extremely buoyant and was used to make fishing floats and rafts. We sequenced two chloroplast loci and the nuclear ITS region and genotyped nine microsatellite loci from samples collected across the species’ range. The different genetic markers produced concordant results and revealed two principal genetic clusters, which were estimated to have diverged during the Pleistocene. The distribution of these clusters shows an east–west split across the northern North Island, which does not correspond to the phylogeographic patterns observed to date for other New Zealand coastal plant species and is difficult to reconcile with any known geological or environmental events. Both clusters were represented in the putative translocated populations indicating that these southern populations had multiple origins. However, the wide distribution of these genetic clusters prevents determination of the source of these southern populations and a natural origin cannot be excluded.