Abstract
Leiopelma hochstetteri belongs to a singular anuran lineage endemic to New Zealand that diverged from other frogs about 200 million years ago. The species now is reduced to a series of isolated populations in the northern half of the North Island and Great Barrier Island. We have used mitochondrial and nuclear sequence data to examine the genetic affinities of extant populations of L. hochstetteri. Phylogenetic reconstructions reveal that populations are highly structured. Each of the geographically isolated populations harbours independent mtDNA lineages as well as different degrees of nuDNA differentiation. Moreover, molecular dating reveals that this structure originated in the early Pleistocene. This pattern of genetic structure likely results from unfavourable climatic conditions during the Pleistocene combined with the low dispersal ability of the species. Isolated populations in forested refugia existed even in the southern part of the distribution of the species during glacial cycles. Previously published variation in chromosome numbers and isozyme data are consistent with the new evidence. We identified 13 evolutionary significant units (ESUs) that should serve as the focus for future management and conservation of this species.