| Summary: | This thesis examines population genetic structure and migration indices of an Antarctic endemic lichen Buellia frigida as well as algal selectivity of the lichens Buellia frigida, Umbilicaria aprina and Umbilicaria decussata in the Ross Sea Region of Antarctica. My aim was to determine where current populations may have originated (i.e. ancient or recent introductions to Antarctica) and if the level of algal selectivity potentially affects colonisation. Chapter 2 reviews historical climate change in Antarctica, particularly in the Ross Sea Region, and introduces the basic characteristics of lichens. It also outlines how molecular analyses of lichen can aid in determining the genetic structure of populations and add to the growing data set which highlights sites in the Ross Sea Region (e.g. Dry Valleys) as glacial refugia. To examine population differentiation between populations in this region it was necessary to develop polymorphic markers capable of delineating individuals. Chapter 3 focuses on the development of five microsatellite markers for this purpose. The initial data for these microsatellites suggested they were suitable for individual genotyping and characterization of B. frigida population structure being mycobiont specific with a high degree of polymorphism. A method of decreasing inhibiting factors present in lichen cells is also provided. In Chapter 4 regional genetic differentiation was revealed by an analysis using microsatellite markers developed in Chapter 3 over 11 populations in five regions of the Ross Sea Region. The identification of three populations with high allelic richness and sites of high dispersal indicated three regions as putative refugia (Terra Nova Bay, Dry Valleys and Beardmore Glacier). Terra Nova Bay has not previously been highlighted putatively as refugia. Limited mixing between adjacent geographical areas (such as the Dry Valleys and Ross Island) was identified, with migration likely to be influenced by wind currents. The photobionts of the lichens Buellia frigida, ...
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