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The phylogeography and systematics of Cardamine hirsuta

<b>Cardamine hirsuta</b> L. is an emerging model system in developmental genetics, where natural genetic variation within <b>C. hirsuta</b> provides the means to investigate the genetic basis of morphological traits. This thesis investigates the geographical structure and genealogical history of genetic variation within <b>C. hirsuta</b> and identifies its closest relatives. This will enable the accurate selection of species for comparison with <b>C. hirsuta</b> when making interpretations of evolutionary processes, and provide a better understanding of morphological character evolution in <b>C. hirsuta</b>. The phylogeographic history of <b>C. hirsuta</b> was reconstructed using multiple chloroplast and nuclear markers and widespread accession sampling from across its native range. A distinct group was identified within <b>C. hirsuta</b>, restricted to the high mountains of East Africa. Climate suitability modelling showed that Pleistocene glacial dynamics have had a strong effect on the distribution of genetic variation within <b>C. hirsuta</b>. The phylogeographical data generated here was used to investigate the origin of <b>C. hirsuta</b> in the Azores, an oceanic archipelago. The Azores are dominated by an endemic chloroplast haplotype which is associated with an endemic phenotype. Thus, <b>C. hirsuta</b> appears to have diversified <b>in situ</b> in the Azores. Phylogenetic analyses of Cardamine, restricted to diploid species to remove the confounding effects of polyploids, found that <b>C. hirsuta</b> is most closely related to <b>C. oligosperma</b>, a western North American species. Multiple loci and extensive intraspecific sampling were brought to bear to demonstrate that <b>C. hirsuta</b> and <b>C. oligosperma</b> are reciprocally monophyletic. <b>Cardamine pattersonii</b>, a restricted endemic from north-west Oregon is likely to be an allopolyploid, with <b>C. oligosperma</b> as the maternal parent and possibly <b>C. nuttallii</b> as the paternal parent.

Identiferoai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:664797
Date January 2013
CreatorsCooke, Elizabeth Laura
ContributorsScotland, Robert; Carine, Mark; Tsiantis, Miltos
PublisherUniversity of Oxford
Source SetsEthos UK
Detected LanguageEnglish
TypeElectronic Thesis or Dissertation
Sourcehttp://ora.ox.ac.uk/objects/uuid:22573e44-881c-456b-a571-d398a04c876a

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