The diversity and zoogeography of Diptera (Brachycera) of disjunct xeric grasslands in the southern Yukon were studied. Over 20,000 flies were collected representing 32 families and 213 species. In terms of abundance, the predacious guild dominated (54% of total specimens) due mostly to the family Chamaemyiidae which represented 45% of all specimens. In terms of diversity, the phytophagous and parasitoid guilds were dominant (25.5% of total species each). The most diverse families were Agromyzidae (32 species), Chloropidae (31 species), Tachinidae (23 species) and Pipunculidae (20 species). Thirty-four undescribed species were collected and 58 species were recorded for the first time in the Yukon. Zoogeographic analysis indicates that the Diptera fauna of these grasslands is dominated by widespread Nearctic or Holarctic species, but the fauna also includes southern grassland species with disjunct distributions, and species endemic to Beringia. The presence of endemic and disjunct species suggests that these grasslands were present in Beringia during the Wisconsinan and acted as a refugium for grassland Diptera.

Thesis of (Ph.D.)--University of Alberta, 2009. / Title from pdf file main screen (viewed on September 14th, 2009). "Fall, 2009." At head of title: University of Alberta. A thesis submitted to the Faculty of Graduates Studies and Research in partial fulfillment of the requirements for the degree of Doctor of Philosophy, Faculty of Physical Education and Recreation, University of Alberta. Includes bibliographical references.

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Ecotones are gradients of change between expanses of similar species composition. These regions often mark co-occurring range limits for several species, and thus are ideal for elucidating ecological and biogeographical phenomena. The forest to tundra transition (FTT) is one of the world's most prominent ecotones, but remains poorly studied especially with regard to vertebrate species occurrence. Vertebrate diversity, ecological structure and resource selection were characterized across the Yukon FTT using diversity metrics, ordination, hierarchical clustering, and resource modeling. The FTT represents an abrupt drop in vertebrate species richness within the more gradual, continental scale diversity gradient. Despite the patchiness and complexity in vegetative structure over this ecotone, the terrestrial vertebrate community is divisible into boreal, taiga, and tundra compartments. Most species conform to resource associations reported closer to the core of their range, generating remarkably consistent habitat and species associations despite a complex patchwork of contrasting habitat types.

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During the summer of 1968 a gravity survey was conducted over the Fox* Glacier, Yukon Territory, for the purpose of finding ice depths. Choice of the Fox Glacier was as a result of its predicted surge, and the survey was part of a long-term analysis of the physical condition of the glacier. Although seismic sounding was attempted, the thinness of the glacier prevented successful results. Analysis of the gravity measurements indicated 88m as the maximum depth; comparison with depths from three drilled holes showed that the gravity results were not seriously in error. A small near-surface temperature program was completed and the results identify the Fox as a sub-polar glacier. *This is not an officially accepted name. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate