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    Population fragmentation in the small-scaled skink (Oligosoma microlepis) : the consequences of human landscape transformation on a habitat specialist's distribution, morphology, and genetics : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Conservation Biology at Massey University, Manawatu, New Zealand
    (Massey University, 2012) Nelson-Tunley, Moniqua
    The endemic small-scaled skink (Oligosoma microlepis) is restricted to the central North Island of New Zealand. Strong preference for exposed rock piles, a relatively rare habitat, has created a fragmented distribution and restricted subpopulation sizes. The Department of Conservation lists the species as in serious decline, with IUCN listing it as vulnerable. At the stronghold of this species in the southern part of its range, subpopulations exist on small rock piles separated by up to 11 km of pastureland. Scattered northern subpopulations are separated by more than 19 km. These distances may act as dispersal barriers, as might the lack of refugia between subpopulations on pastureland. Lack of migration between subpopulations could reduce genetic diversity and increase inbreeding. Reduced genetic diversity could decrease resistance to disease, parasitism and environmental change, whereas inbreeding may reduce fertility, lifespan and juvenile survival. This thesis used a combination of survey data, morphological measurements and population genetics to investigate potential causes and consequences of population fragmentation on the small-scaled skink, with the aim of providing information to guide the long-term conservation of this species. A survey of known small-scaled skink subpopulations was conducted to determine if the species is in decline. In addition, potential small-scaled skink habitat was searched, including previously surveyed sites. Evidence of decline was inconclusive, with three subpopulations appearing to be in decline and discovery of five new subpopulations. Genetic (16S mitochondria and microsatellites) and morphological analysis was used to examine subpopulation differences in relation to species distribution, including investigating inbreeding within subpopulations. Relatedness between subpopulations was consistent with isolation by distance, indicating that small-scaled skink dispersal is limited by distance, but not significantly limited by pasture between subpopulations. Inbreeding was not detected within any subpopulation.The main findings of this thesis were that evidence of species decline was inconclusive, with possible species expansion and undetected subpopulations. Dispersal was limited by dispersal distance but not by pasture and no subpopulation was subject to significant inbreeding. Current research indicates that pasture does not negatively affect the species, and may be beneficial in the formation and maintenance of habitat.
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    Sequences and signals : evolutionary histories of New Zealand skinks : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Genetics at Massey University, New Zealand
    (Massey University, 1993) Hickson, Robert Eric
    The application of DNA sequencing to studies of the New Zealand biota is illustrated by investigations into the evolutionary relationships of skinks in the genus Leiolopisma. DNA sequences from a region of the mitochondrial 12S rRNA gene were determined for 20 taxa by use of the polymerase chain reaction. A vertebrate secondary structure model for this part of the gene was developed using comparative sequence analysis and calculations of RNA folding energies. Approximately one third of the molecule does not vary between the vertebrates examined, and there are similar patterns of sequence variability among the vertebrates. The secondary structure model was subsequently used to assist phylogenetic analyses of the skink sequence data set. Analyses of the mitochondrial DNA sequence information, using newly developed and more sophisticated algorithms, did not produce a fully resolved phylogenetic tree for all the skinks, though relationships between some taxa are less ambiguous. The lack of resolution does not appear to be due to limitations in the analytical methods, nor to the patterns of nucleotide substitutions in the skink 12S rRNA sequences. The skink sequence data set is unusual in that most of the taxa have similar numbers of nucleotide substitutions when compared to each other. These results are interpreted as reflecting a rapid divergence of the Leiolopisma group of skinks. Simulation studies support this interpretation. Three hypotheses are presented to account for the patterns of sequence differences between the skinks. One proposes a Gondwanan divergence of the Leiolopisma group, about 80 million years ago. Under this hypothesis the distribution of the skinks on islands in the Pacific and Indian oceans can be explained, in part, by continental drift. A second hypothesis suggests that New Zealand Leiolopisma are derived from a Miocene (15-25 million years ago) evolutionary radiation in New Zealand. This hypothesis however is inconsistent with observations of the sequence similarities between Mauritian, Australian, and New Zealand skinks. A third hypothesis, proposing several independent colonizations of New Zealand by Leiolopisma, is also not as well supported by the available sequence data. However, a close relationship between the 12S rRNA sequences of one New Zealand species L. infrapunctatum and the Australian Lampropholis guichenoti suggests that at least two skink immigrations to, or emigrations from, New Zealand may have occurred. Predictions of the three hypotheses and strategies to test them are discussed. Some of the conclusions derived from analyses of the mitochondrial DNA sequences conflict with those obtained from allozyme information, though there are points of agreement. Comparison of the allozymc and sequence data do also revealed a case of hybridization between two sympatric species, L. n. polychroma and L. maccanni, at a site in Southland. Analyses of both data sets indicate that the morphological similarity of Leiolopisma species obscures a large amount of genetic diversity, and the evolutionary histories of New Zealand Leiolopisma are older and more complex than previously considered. Further genetical and ecological studies of Leiolopisma are required, but this thesis emphasizes both the suitability and necessity of molecular genetic approaches for evolutionary investigations in New Zealand.
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    The prevalence of Salmonella and the spatial distribution of its serovars amongst New Zealand's native lizards : a thesis presented in partial fulfillment of the requirements for the degree of Master of Science in Zoology at Massey University, Palmerston North, New Zealand
    (Massey University, 2008) Middleton, Danielle Mary Rose Lea
    This thesis considers the prevalence and spatial distribution of Salmonella serovars amongst wild endemic lizards on offshore islands around the coast of New Zealand. The mean test prevalence of faecal excretion of Salmonella was 4.7%. Skinks (Scincidae) were more likely (8.5%) to be carriers of Salmonella than geckos (1.6%). Each island was host to between one and three Salmonella serovars that were not found on any other islands in this study. Two exceptions were Salmonella Bousso and Salmonella Mana which were found on two islands within the same geographical area. Based on the findings of this study, different islands are likely to be hosts to different Salmonella serovars which could have implications for future translocations of native lizards. I also assessed the prevalence and spatial distribution of faecal excretion of Salmonella, Aeromonas and Hafnia alvei within Mana Island. The prevalence of Salmonella on Mana Island was estimated at 5.8%. Salmonella was found predominantly in skinks (10.0%) and less often in geckos (4.1%). H. alvei was found at a prevalence of 1.9%. No Aeromonas species were cultured from any of the cloacal swabs, suggesting that the 95% confidence interval for the true prevalence is 0-3%. Each site sampled in this study was host to one or more unique serovar of Salmonella not found at any of the other sites. The results of this study indicate that Salmonella serovars may become established within populations of lizards and is not spread between them. This may be due to a lack of dispersal of lizards between sites, raising important considerations for the translocation of native lizards. I investigated the prevalence of faecal excretion of Salmonella, H. alvei and Aeromonas by New Zealand native lizards from two captive populations. The mean prevalence of faecal excretion of Salmonella in the captive lizards sampled was 11.5%. There was a higher prevalence of Salmonella within captive population A (22.0%) than in population B (3.6%). No Aeromonas was cultured from any of the lizards. H. alvei was found at a prevalence of 5.2%. The prevalence of Salmonella and H. alvei was significantly higher in captive lizards than in wild populations. Captive lizards may, therefore, not be appropriate founders for new populations of wild lizards. Finally I assessed the different efficiencies of two media and two temperatures in isolating six Salmonella serovars from a reptilian source. All serovars grew equally well at 37°C and 27°C. For most serovars XLD agar was the more successful media than MacConkey agar but the success of different culture media depended on the serovar being cultured. Because lizards are frequently host to a wide range of Salmonella serovars, screening samples using multiple microbiological methods is likely to give the best chance of isolating all Salmonella serovars present.