Molecular phylogeny of the genus metrosideros and population genetics of some New Zealand species within the genus. (2017)
Type of ContentTheses / Dissertations
Thesis DisciplineBiological Sciences
Degree NameDoctor of Philosophy
PublisherUniversity of Canterbury
This thesis attempts to answer three questions about the phylogeny and genetics of the New Zealand genus Metrosideros which contains iconic tree species of New Zealand. The first question (Chapter 2) is at the scale of the genus and attempts to resolve the phylogenetic relationships within the Metrosideros group. At the same time, based on the molecular phylogeny, inference is made on the dispersal route of the genus from New Zealand to the Pacific. In doing so, this chapter tests two hypotheses (1) the current classification of genus Metrosideros is supported by the genetic data and (2) the current distribution of genus Metrosideros in the Pacific is a result of long distance dispersal from New Zealand rather than due to ancient Gondwanan connection among the Pacific islands. Molecular phylogeny studies have shown that the biogeography of New Zealand species is shaped mainly by transoceanic dispersal rather than Gondwanan connection (Pole, 1994; McGlone et al., 2001; Winkworth et al., 2002; Perrie & Brownsey, 2005; 2007; Cantley et al., 2016). Hence, this chapter attempts to test if this is true for the New Zealand genus Metrosideros.
The second question (Chapter 3) is at the scale of the population with a focus on the critically endangered New Zealand endemic Metrosideros bartlettii. Population genetics are used to assess the genetic diversity and structure of this species with applications for conservation management. This chapter tests the hypothesis that M. bartlettii populations have a low genetic diversity relative to equivalent species because of the very small size of the current populations. In other words, the chapter attempts to test if the correlation between population size and genetic diversity is positive as reported in the literature (e.g. Cole, 2003; Leimu et al., 2006; Solórzano et al., 2016).
Chapter 4 addresses the third question, which is again at the population scale and investigates hybridisation between two New Zealand endemic species (M. excelsa and M. robusta) on Rangitoto Island. The extent, pattern and implications of hybridisation between these two species are discussed in detail. This chapter tests the hypothesis that hybridisation occurs between M. excelsa and M. robusta on Rangitoto Island as reported by several sources (Cooper, 1954; Allan, 1961; Julian, 1992; Wilcox, 2007; Dawson et al., 2010b).
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