Biodiversity and conservation across landscapes and regions

Many hypotheses have been advanced to explain spatial variability in species richness, one of the central problems in ecology. By gaining an understanding of spatial patterns of diversity across regions and landscapes and the factors that predict them, several long-standing research issues in conservation biology may be effectively addressed. In this thesis, I have developed empirical models that assist in the prediction of diversity across a range of spatial scales and geographical areas while testing major hypotheses of diversity.; My primary accomplishment has been the discovery of a two-factor model that predicts mammal and Papilionidae species richness far better than older models based on potential evapotranspiration (PET: a measure of climatic energy) alone. My approach includes both PET and habitat heterogeneity. Pet predicts species richness when maximal annual PET < 1000 mm y–1 (corresponding approximately to the Canada-US border) while habitat heterogeneity predicts richness south of this region. I also present results for Epicauta (Coleoptera: Meloidae, blister beetles) that support the species richness-energy hypothesis, while arguing against the frequent acceptance of historical explanations of diversity, such as those relying on evolutionary history or glacial events.; Alternative explanations of large-scale patterns of species richness are often cited, regardless of whether they have received much empirical support or even make any testable predictions. I refute two such hypotheses, the biome hypothesis and Rapoport's rule, and show that the species richness-energy hypothesis provides good predictions of species richness among several taxa at a regional scale.; Based on the models predicting species diversity patterns collected in earlier chapters, I address several general conservation biological points. The umbrella species concept, which states that establishing a reserve for a few focal taxa, typically large vertebrates, will incidentally conserve a large number of additional species, is unreliable. In addition, debate over whether conservation efforts should be directed at centres of endemism or high diversity is misplaced, at least in North America, as they coincide to a large degree in this region.; Chapter 7 combines species richness-energy theory with estimates of anthropogenic climate change to present a model of where mammal diversity is likely to undergo the most severe changes. I find there to be considerable regional variability in presumptive mammal community responses to projected warming and major range contractions among organisms whose northern distributions are bounded by the Arctic Ocean.; Conservation actions must often be taken at the landscape scale, and will be aided substantially by improving current techniques to assess biodiversity. I examine lepidopteran and hymenopteran diversity in severely fragmented remnants of oak savanna habitat in southern Ontario to estimate the utility of indicators and rapid biodiversity assessments in biodiversity monitoring. Because many taxa are difficult to identify, rapid biodiversity assessments may also assist in monitoring efforts. I also find that these habitats exhibit a nested subsets pattern: the lepidopteran and hymenopteran species present in low diversity savanna remnants tend to be subsets of the biota present in higher diversity remnants. This pattern is expected if extinctions have reduced the diversity of some patches. (Abstract shortened by UMI.)...