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Subject: search.filters.subject.Korthalsella salicornioides

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    Host-race specificity in the endemic pygmy mistletoe Korthalsella salicornioides (Viscaceae) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Plant Biology at Massey University, Palmerston North, New Zealand
    (Massey University, 2016) Pearson, Sofie Margaret
    Korthalsella Tiegh. is a genus of stem hemiparasites in the family Viscaceae, represented in New Zealand by three endemic species: K. clavata, K. lindsayi, and K. salicornioides. The most host-specific is K. salicornioides as it parasitizes two main host genera Leptospermum (Myrtaceae) and Kunzea (Myrtaceae), while the other two species are considered generalists parasitizing a wider range of host species. K. salicornioides is naturally uncommon and sparse, although it can be locally abundant on occasion. Mistletoe populations are at risk primarily due to habitat destruction and subsequent loss of hosts. Cross-infection experiments in K. salicornioides provided some insight into the presence of putative host races, as better mistletoe seedling establishment success rates were apparent when the maternal and recipient hosts were the same. However, because previous molecular sequence data (nuclear internal transcribed spacers and chloroplast trnQ-rps16) for K. salicornioides were not informative about specific host-races, more rapidly evolving molecular markers might be expected to detect host races. In this study, next generation sequencing was used to develop novel microsatellite markers for Korthalsella. Eleven markers were reliably amplifiable and the most polymorphic for K. salicornioides were used to genotype 272 K. salicornioides individuals from 16 populations. Across all populations few alleles were identified, and within-population assessment of genetic variation indicated that many populations have low levels of genetic diversity and high proportions of homozygotes. Despite the presence of few alleles, a high degree of genetic differentiation between most populations was detected and was found to reflect host species and geography. The findings of this study that Korthalsella salicornioides populations have low levels of genetic variation but host-specific races, has important conservation implications. The main conservational focus should be maintaining and increasing host Leptospermum and Kunzea populations. The spread of mistletoe seed on hosts within or between populations may also increase the chances of continued survival. However, it is imperative that genetic material comes from the same host species, and consideration should also be given to the geographic area, especially in the Wairarapa. This study provides insights into the population structure within and between the different host populations and suggests several interesting areas of future study.
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    Systematics, biology and ecology of New Zealand's pygmy mistletoes (Korthalsella: Viscaceae) : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Ecology at Massey University, Manawatu, New Zealand
    (Massey University, 2014) Sultan, Amir
    New Zealand’s pygmy mistletoes belong to the genus Korthalsella Tieghem, which comprises about 30 species ranging from Malesia to Hawaii, the Marquesas and Henderson Islands in the east, Japan in the north, Australia, New Zealand in the south, and Ethiopia and Madagascar to the west. Mainland Australia, Hawaii, Malesia and Madagascar all have high levels of species richness. This thesis shows that Korthalsella has high levels of regional endemism and has widespread parallelism and supports the biogeographic model of speciation, whereas, the traditional sections based on morphology are not supported. Korthalsella is represented in New Zealand by a monophyletic clade of three species K. clavata (Kirk) Cheeseman, K. lindsayi (Oliver ex J. D. Hooker) Engl., and K. salicornioides (A. Cunningham) Tiegh. Korthalsella clavata and K. lindsayi are both generalists with relatively broad host ranges whereas K. salicornioides is a specialist species with most host records from two myrtaceous genera Kunzea Rchb. (kanuka) and Leptospermum J. R. Forst & G. Forst (manuka). Cross-infection experiments in Korthalsella salicornioides indicate the presence of putative Kunzea- and Leptospermum-specific races with better success rates of seedling survival when maternal and recipient hosts were the same. However, genetic data based on nuclear internal transcribed spacer (ITS) and chloroplast trnQ-rps16 spacer sequences does not support the presence of host related variability and the within-species genetic structure appears to be geographic rather than host-based. My study shows that both cpDNA haplotypes and ITS sequence types are shared between K. clavata and K. lindsayi, which possiby is an outcome of hybridisation and introgression between the two species. Korthalsella salicornioides is an ambophilous species relying both on insects and on wind for effective pollination, whereas K. lindsayi is an anemophilous species. This study confirms the presence of explosive seed discharge in both species with dispersal distances ranging up to 4 and 7 m in K. lindsayi and K. salicornioides, respectively. However, dispersal distances of around 1 m are more typical. This study also describes the first account of clonal propagation by means of proliferation of endophyte and formation of adventitious sprouts in these species. Several new natural enemies specialising on New Zealand Korthalsella were discovered - two specialist armoured scales (Leucaspis albotecta Henderson and L. trilobata Henderson), a felt scale (Eriococcus korthalsellae Henderson), and two pathogenic ascomycetes Guignardia korthalsellae Sultan, Johnston, Park & Robertson and Rosenscheldiella korthalsellae Sultan, Johnston, Park & Robertson. Other natural enemies include a specialist gall mite Aceria korelli Manson, whereas generalists include native and adventive scale insects and generalist Lepidoptera. Demographic study of several populations revealed that all species have high growth rates and high ramet turnover. Korthalsella salicornioides and K. clavata had relatively stable recruitment rates in all size/stage classes whereas K. lindsayi populations were apparently declining at the two study sites.