Conservation Genetics of North Island Kōkako (Callaeas wilsoni)
Milner-Jones, Meghan A. E.
Conservation genetics has recently been recognised as an important, although often overlooked, aspect of wildlife management. Applying molecular techniques and genetic concepts to management strategies has the potential to significantly improve current and future recovery efforts. Wildlife translocations are often used for threatened species management in New Zealand, in which the selection of appropriate source populations is an important decision. North Island kōkako (Callaeas wilsoni) are an endemic, threatened songbird distributed across 24 relict and translocated populations in the North Island of New Zealand. Translocations have significantly influenced kōkako recovery. As such, kōkako are one of the most commonly translocated species in New Zealand. Integrating genetic techniques and recommendations into source population selection will help ensure the long-term success of future translocation projects. Te Hauturu-o-Toi is currently the largest population of kōkako but is thought to have been established by a founding population of as few as nine individuals. The aim of this research was to assess the suitability of the Hauturu kōkako population as a future source for translocations using molecular methods. In particular, the aim was to address two aspects of a source population that contribute to the overall success of a translocation; genetic diversity and disease status. To do so, the level of genetic variation across six populations and the presence of Psittacine Beak and Feather Disease on Hauturu was examined. Such research provides conservation managers with important genetic information that can be applied to best protect kōkako in future. Conserving genetic diversity is important for long-term survival of endangered species. As translocations involve a small number of individuals and create a genetic bottleneck, sourcing founder birds from genetically diverse populations helps ensure long-term translocation success. I developed 21 kōkako-specific microsatellite primers using a whole kōkako genome, that were then multiplexed to infer genetic diversity and population structure in one translocated (Hauturu) and five relict (Mapara, Mangatutu, Te Urewera, Waipapa and Bay of Plenty) kōkako populations. A similar level of genetic diversity was apparent across all populations, providing evidence to support the use of Hauturu as a source for future translocations. Both multivariate and Bayesian methods recognised a clear population structure (K=3), identifying kōkako from Hauturu and Mapara as genetically distinct from the other four sites. Understanding the differentiation between kōkako populations will allow managers to plan translocations that maximise genetic diversity and hence translocation success. Disease risk and spread has the potential to induce a translocation failure. A kōkako on Hauturu developed aberrant coloured plumage and features (claws, legs, beak) between sampling seasons (2013–2015), reminiscent of Psittacine Beak and Feather Disease (PBFD). PBFD typically infects psittacine species, but due to high recombination rates can host-switch for infection in non-psittacine species. The Hauturu population was screened for PBFD using polymerase chain reaction, with all individuals (n=31) testing negative. There is no evidence for a host switching event from red-crowned parakeets (Cyanoramphus novaezelandiae) on Hauturu into kōkako, therefore, a translocation from Hauturu is unlikely to facilitate PBFD spread. Following this result, the melanocortin-1 receptor (MC1R) gene was amplified as an alternative explanation, looking for sequence variants between the before (normal), after (aberrant) and seven normal kōkako (also from Hauturu). The MC1R gene was selected as it has a pleiotropic role in regulating both melanin deposition and physiological stress responses. No mutational differences were found, and it is recommended that future research includes screening of alternative candidate genes or explores epigenetic mechanisms to provide an explanation for the observed phenotype.
Advisor: Robertson, Bruce
Degree Name: Master of Science
Degree Discipline: Zoology
Publisher: University of Otago
Keywords: North Island kōkako; Conservation genetics; Population structure; Microsatellite; Wildlife management; Psittacine Beak and Feather Disease; Melanocortin-1 receptor gene
Research Type: Thesis