LE3 .A278 2004

2004

Stewart, Don

Acadia University

Master of Science

Masters

Biology

Biology

Southern flying squirrels ('Glaucomys volans' (L.)) occur throughout most of eastern North America with disjunct populations in Central America and Nova Scotia (NS), Canada. Mitochondrial cytochrome-'b' (cyt-b) and control region (CR) sequence data were used to investigate geographic variation and phylogeography of the NS population and the following hypothesis is suggested. Following the last glaciation (~12Kya), 'G. volans ' rapidly expanded its range from a southern refugium. It was then isolated in southwestern NS during subsequent climactic fluctuations. The low level of variation observed in cyt-b sequences (0-2.1% divergence) suggests a rapid range expansion. The low variation in cyt-b sequence data makes 'G. volans' from NS genetically indistinguishable from other populations. However, CR sequences did demonstrate differentiation (0.5-5.7% sequence divergence) over the entire range. Nested-clade phylogenetic analysis (NCPA) of CR sequences suggests that the NS population was isolated by the loss of intermediate populations. NCPA also suggests that a range expansion occurred within NS. This event dates to ~2Kya which is coincident with beneficial habitat changes (i.e., an increase in oak abundance) suggested by pollen core studies. In NS, 20 CR haplotypes were identified, although two of these were found in 57% of the individuals sampled. A possible explanation for this relatively limited level of genetic variation is that the NS population experienced a bottleneck event. Although the 'G. volans' population in NS would not be considered an evolutionary significant unit under some definitions, CR sequence data could be used to identify individuals to augment populations that are in peril.

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