There is great interest in ecology to determine the drivers of species richness. For many taxa, and in natural circumstances, temperature is often found to be a good predictor of richness. The goal of this thesis was to determine, amongst several human-related and natural, environmental and ecological variables, the most important broad-scale predictors of butterfly species richness across Canada. Also, I presented a test of whether spatial relationships are adequate surrogates for the temporal relationship between richness and predictor variables. Using precisely georeferenced and dated butterfly records across Canada, I created butterfly species richness maps for two periods (1900-1930 and 1960-1990), and then related them to candidate predictors. Natural variables such as temperature, precipitation and soil type tended to explain most of the variance in species richness, while human-related variables such as habitat fragmentation, habitat heterogeneity and pesticide density added very little. A comparison of temporal and spatial relationships showed that temperature was a consistent predictor of richness through time and space, but that the impact of human activities on richness differed. My results are consistent with the species-energy hypothesis while showing that human-related variables are not having a large measurable effect on butterfly species richness patterns in Canada at broad scales. Also of critical importance in this thesis is the difference I found between the spatial and temporal relationships of richness vs. human activity level. I show that the assumption commonly made in macro-ecology that spatial variables are appropriate surrogates for temporal ones, is not always correct.
| Identifer | oai:union.ndltd.org:uottawa.ca/oai:ruor.uottawa.ca:10393/27196 |
| Date | January 2005 |
| Creators | White, Peter J. T |
| Publisher | University of Ottawa (Canada) |
| Source Sets | Université d’Ottawa |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 73 p. |
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