Molecular Systematics and Conservation of the Cyanoramphus Parakeet Complex and the Evolution of Parrots

Abstract

This thesis is mainly focused on the molecular evolution, systematics and conservation of the Cyanoramphus parakeet complex and also the parrot order as a whole. The conclusions in this study were derived from DNA sequences of three mitochondrial DNA loci; cytochrome b, control region and l2S rDNA, some sonography, morphology, conservation management and field observation data It was found that although mitochondrial DNA data alone was sufficient in answering many of the taxonomic and evolutionary questions posed, the incorporation of data from other fields of research increased the confidence of the conclusions made substantially. The taxonomy of the Cyanoramphus complex of parakeets have been (almost) completely revised. Five new species, C. saisetti, C. cooki, C. malherbi, C. forbesi, and C. erythrotis and one new subspecies, C. e. hochstetteri have been identified by this study. The revised total number of species and subspecies in this complex currently stands at ten and four respectively. The other five species and three subspecies with unchanged classifications are C. zelandicus, C. ulietanus, C. novaezelandiae, C. auriceps, C. unicolor, C. n. chathamensis, C. n. cyanurus and C. n. subflavescens. The rare Ouvea parakeet (Eunymphicus cornutus, uvaeensis) from Ouvea Island to the North-East of New Caledonia, was also elevated to full species status as E. uvaeensis. With respect to the new taxonomic classifications, many conservation implications were discussed. This was particularly so for rare or endangered taxa with erroneous taxonomy in the past. This piece of investigation also highlighted that poor taxonomy was not to be taken lightly and that taxonomic errors may accelerate the rate at which species become extinct in the future. The use of species concepts and associated speciation theories in taxonomy and systematics was also discussed. Although conservation issues did not dominate this study, they were definitely an important issue for the study of the Cyanoramphus parakeets in particular. Due to many pre-1900's taxonomic classifications (of which many were erroneous), several taxa in this genus were not afforded the same 'legal' protection as those with a full species status. The conservation implications of having a revised taxonomy is large and was discussed in several of the chapters. Recommendations for conservation practices were also included based on the findings of this study. As for the evolution of the New Zealand Cyanoramphus parakeets, they have been determined to have radiated out from New Caledonia during the last 500,000 years. The Eunymphicus parakeet genus from New Caledonia was also shown to share the most recent common ancestor with Cyanoramphus about 2.5 million years ago (MYA) while the Australian Platycercus genus was the closest taxon to Eunymphicus, sharing a common ancestor about 30 MYA. The current Cyanoramphus parakeet taxa have been postulated to have arisen via allopatric speciation in small 'refugia' during the late Pleistocene and Holocene due to glacial- interglacial fluctuations. Based on the cytochrome b and l2S rDNA datasets, we support previous claims that the parrot order of birds can be subdivided into three main geographical locations; the Australasian, Afro-Asian and Neotropical groups. These three regional groups of birds are made up of seven lineages. The four Australian lineages are represented by the cockatoos from Australia/New Guinea, the Platycercines from Australia (which includes the island endemics; Cyanoramphus, Eunymphicus and Prosopeia) and other parrots, the lorikeets and the Nestor/Strigops lineage from New Zealand. The other three lineages are made up of the short-tailed Neotropical parrots, long-tailed Neotropical parrots and the African parrots. With the use of albatross/penguin fossil and genetic data, the divergence times of the taxa within the parrot order were calculated using various different techniques. In all of the analyses, the origin of parrots were determined to pre-date the K/T boundary (>65 MYA). As a result of the ‘global' parrot dataset analysis, further conclusions on the phylogenetics and evolution of the parrot order were made possible.