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Margaret HeslewoodResearch student and member of scientific staff - see Margaret Heslewood - systematics and evolution in plants and animals Supervisors Degree University Project title Project details This study will encompass investigations of genetic divergence at a hierarchy of spatial and temporal scales to elucidate the roles of vicariance and long distance dispersal (LDD) in shaping the present day genetic structure and distribution of taxa within the family Cunoniaceae, focussing on the genus Ceratopetalum. Relationships within the family will be resolved through cladistic analysis of molecular sequencedata (nuclear and chloroplast) producing an estimate of the phylogeny. Examination of this estimate in light of the geographical distributions of the taxa will reveal underlying biogeographic patterns over a range of spatial scales. Constraining the phylogeny against dated fossil and geological evidence will elucidate the impacts of vicariance and LDD in explaining the biogeographic pattern of present day species distributions. At the species level, phylogeography can be used to reveal historical components of gene flow by examining the phylogenetic relatedness of alleles as well as their spatial arrangement among populations. Comparative phylogeography of several narrow range endemic species of Ceratopetalum in the Australian Wet Tropics, and of two broadly distributed taxa in NSW and SE Queensland will be examined. While LDD is likely to be a stochastic process and unique in time and space within a species, genetic breaks of similar depth and geographic location amongst a number of taxa might suggest a vicariant barrier to gene flow. Within Ceratopetalum apetalum, population genetic analyses will be used to look for genetic structure within and among populations in order to detect patterns of current gene flow (as detected through allelic frequencies at nuclear microsatellite loci) over both short and long-distances (LDD). High levels of structure within and among populations would be indicative of effective barriers to gene flow. At the finest scale, spatial genetic structure (SGS) will be examined to compile a snapshot of genetic composition over recent time by examining plants of different age classes within a discrete population. A correlation between genetic relatedness and spatial distance among adults in the populations would indicate the presence of fine-scale genetic structure, perhaps due to restricted dispersal of pollen and/or seed. Keywords biogeography, long distance dispersal, vicariance, phylogeography, population genetics, microsatellite Contact details Margaret Heslewood |
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