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Reimchen, Superviser (Department of Biology) Co-supervisor (Department of Biology, Centre for Environmental Health) _______________________________________________________________________ Dr. D. B. Levin, Departmental Member (Department of Biology, Centre for Environmental Health) Dr. R. J. Hebda, Departmental Member (Department of Biology, Royal BC Museum) Mr. D. W. Nagorsen,^ Outside Member (Royal BC Museum) Dr. R. W/Mathewes, External Examiner (Department of Biology, Simon Fraser University) © S. Ashley Byun, 1998 University of Victoria All rights reserved. This dissertation may not be reproduced in whole or in part, by photocopying or other means, without the permission of the author. 11 Supervisors; Dr. T. E. Reimchen and Dr. B. F. Koop Abstract Population fragmentation and subsequent isolation in different réfugia during the glacial advances of the Pleistocene are believed to have had a significant impact on current levels of genetic and morphological diversity. Despite the importance of these glacial réfugia for biodiversity, our understanding of their distribution on the northwestern coast of North America and their relative impact on populations remains limited. As the most isolated group of islands in the Pacific Northwest, Haida Gwaii has been the subject of intense study both from the perspective of its complex glacial history and endemic flora and fauna. The ubiquitous presence of glacial features on this archipelago points to extensive ice cover during the late Wisconsin (Fraser glaciation) and populations which could only have become established postglacially. However, the large assemblage of unique mammalian and avian fauna found on Haida Gwaii has led to suggestions that these divergent vertebrates actually evolved through long isolation by continuously inhabiting these islands or nearby regions throughout the last glacial maximum. To assess Haida Gwaii’s role as a glacial refugium and the relictual status of its endemic black bear (JJrsus americanus), marten (M artes americana), short­ tailed weasel (Mustela erminea), caribou (Rangifer tarandus) and Saw-whet Owl (Aegolius acadicus) , a broad phylogeographic study using sequence comparisons of the mitochondrial gene cytochrome b was undertaken. Phylogeographic structure was observed in the black bear (n= 33), marten (n= 18) and short-tailed weasel (n= 32). Based on parsimony, maximum likelihood, and neighbour-joirting analyses of 719 bp of cytochrome b, two geographically structured black bear lineages were 111 unambiguously identified: 1) a continental lineage found in the Yukon, Alberta, Alaska, Montana and Pennsylvania {americanus) and mainland BC {americanus and cmnamomuni) and 2) a coastal lineage found on Haida Gwaii {carlottae), Vancouver Island iyancouveri) and the Olympic Peninsula {altifrontalis). The two lineages were defined by 24 synapomorphies and an average sequence divergence of 3.6%. Average intralineage divergence was 0.1%. Similarly, two geographically structured lineages, continental and coastal, were also identified in marten using the same types of analyses on 3II bp of cytochrome b. The continental lineage included marten from mainland BC {caurina and abietinoides) and Newfoundland {atrata) whereas the coastal lineage included marten from Haida Gwaii {nesophila) and Vancouver Island {yancouverensis). The two lineages were defined by three synapomorphies and an average sequence divergence of 1.2%. Average intralineage divergence was 1%. Phylogeographic structure was also observed in the short­ tailed weasel using 148 to 673 bp of cytochrome b. Three major lineages were identified and named according to their putative réfugiai source areas: Beringia, which included weasels fi"om Japan {orientalis) and the Yukon {arcticd), a continental or southern source, which encompassed weasels from mainland BC (richardsonii, invicta,fallenda), Manitoba {bangsi), and Ontario {cicognanii\ and Haida Gwaii which included only those weasels from Haida Gwaii {haidarum). Short-tailed weasels fi"om Vancouver Island {anguinae) and some areas along the coast demonstrated an affinity to both southern and Haida Gwaii weasels. Relative to the continental lineage, the coastal lineage was defined by 13 synapomorphies; the Beringian lineage was defined by 10 synapomorphies. Average sequence divergence was 2.5 % and 2.2% respectively. Divergence between the coastal weasels and Beringian weasels was 2.4%. There was little mtDNA diversity within the coastal lineage as the average intralineage divergence was 0.8%. Little or no phylogeographic structure was observed in the caribou and Saw-whet Owl. O f the 313 bp examined in two barren ground caribou {granti) and seven I V woodland caribou (four tarandus and three dawsoni), threetarandus and two dawsoni formed a lineage defined by one synapomorphy. The two barren ground, one tarandus, and one daw soni were excluded from this lineage by one to three substitutions. Similarly, little phylogeographic structure was observed in the Saw- whet Owl. Analyses o f a 241 bp of cytochrome b sequenced from this species indicated no genetic divergence between individuals as far apart as Haida Gwaii (brooksi) and Manitoba {acadicus'). The maximum divergence observed between individuals was 0.4%. The phylogeographic patterns from these five species have two major implications with regard to the issue of glacial réfugia and the relictual status of the Haida Gwaii endemics; 1) With the possible exception of haidarum, the suite of morphological features characterizing the endemics carlottae, nesophila, dawsoni and brooksi appear to have been derived postglacially. In fact close genetic affinity of these endemic subspecies with adjacent conspecifics suggest that population fingmentation caused by glaciers has had little effect on morphological differentiation and that adaptation to local ecological environments has played a more influential role in their evolution. 2) Emerging data of a mid-Pleistocene split of many vertebrate taxa and the geographic distribution of these various generic lineages, including the black bear, marten and short-tailed weasel in this region cumulatively suggests that a refugium existed on the continental shelf off the central coast of British Columbia and was possibly part of a larger (or series of réfugia) refugium which extended further north and south along this coast. Given the broad assemblage of taxa which might have persisted here during the last glaciation, this refugium was probably ecologically productive and as such, was likely to have been an important alternate source area for the postglacial recolonizarion of northwestern North America. Keywords: Haida Gwaii, Queen Charlotte Islands, Pacific Northwest, réfugia, Wisconsin glaciation, Fraser glaciation, Cordilleran Ice Sheet, black bear, marten, short-tailed weasel, caribou, Dawson caribou, Saw-whet Owl, endemism, mtDNA, cytochrome b, phylogeography, postglacial dispersal routes, biogeography Examiners: Dr. T. E. Reimchen, Supervispr (Department of Biology) ^^0t5p, Co-supervisor (Department of Biology, Centre for Environmental Health) Dr. D. B. Levin, Departmental Member (Department of Biology, Centre for Environmental Health) Dr. R. J. Hebda, Departmental Member (Department of Biology, Royal BC M usei^) Mr. D. W. Nagorsen, Outside Member (Royal BC Museum) Dr. R. W. Mathewes, External Examiner (Department of Biology, Simon Fraser University) vu Table of Contents Title p a g e ................................................................................... i A b s tra c t................................................................................ii-vi Table of Contents .............................................................vü-xii