Genetic Variation and Conservation of Kaka (Nestor meridionalis)

Abstract

Kaka (Nestor meridionalis) are parrots that are endemic to New Zealand. Once very abundant in forested parts of the North and South Islands, populations have been declining since European occupation, largely because of predation and competition from introduced animals, forest destruction and hunting pressure. The Department of Conservation considers the kaka to be a threatened but not yet endangered species. Currently two subspecies are recognised, the North Island (Nestor meridionalis septentrionalis) and the South Island (Nestor meridionalis meridionalis) kaka. Taxonomy plays an important role in assigning conservation priorities to species and is one of the criteria used by the Department of Conservation. Priorities for kaka would change significantly if it was found that the subspecies were in fact different species. The goal of this study was to evaluate the taxonomy of kaka to assist in their conservation. Genetic differentiation of the two subspecies was thus investigated through allozyme electrophoresis. Blood samples were collected from kaka populations representing their entire geographical range. Kaka variation was compared to that between and among related species including the kea and some parakeet species. Twenty presumed genetic loci were characterised, and three were polymorphic within kaka populations, Es, F-Es-2 and Mpi. The Kapiti Island population possessed a rare allele at the F-Es-2 locus. One polymorphic locus was found within the kea (Mdh-2), and one within the parakeets (Mpi). The genetic variation found among kaka populations was very small and showed no geographical pattern. Allozyme electrophoresis found no genetic evidence to support separate kaka species. It is recommended that DNA sequencing be used to clarify the current subspecies status of the North and South Island kaka and that the Kapiti Island population be treated as a separate management unit to the other kaka populations sampled.