|Cane, James - Jim|
Submitted to: Annual Meeting of Southern Arizona Parks and Monuments Association
Publication Type: Proceedings
Publication Acceptance Date: 8/1/1998
Publication Date: N/A
Citation: Interpretive Summary: Comparisons of bee species diversity, taxonomic similarity and guild persistence are rarely available for time periods spanning more than a few years. These few decadal-scale studies available mostly explain losses or shifts in species diversity of native bee communities as a response to changes in land use. We have found that the proportion of Larrea (creosote bush) oligoleges (taxonomic host specialist) for a given locality's bee fauna at flowering Larrea can be predicted by the antiquity of Larreacoloni n. At the oldest sites, where Larrea first colonized late in the Wisconsin glaciation, flowering Larrea today hosts a guild of bees dominated numerically by its oligoleges. Conversely, at sites where creosote bush has only arrived late in the Holocene, and especially in historical times, its bee fauna is dominated by native floral generalists.
Technical Abstract: For the inter-annual comparisons, average variability in a bee species' abundance at a site was related to overall species abundance, such that more common generalist or specialist species varied more between years in their abundance, such that more common generalist or specialist species varied more between years in their abundance at Larrea flowers than did rarer species. Regionally more abundant bee species were more likely to be re-sampled at our individual 1-ha sites than regionally rarer species. The overall fraction of bee species that we collected in two sequential years or two sequential decades at a given site was no more than that expected by chance when drawing from the log-normal distribution of regional bee species abundance at Larrea. Thus, local persistence is predictable from regional abundance, but abundances can be markedly variable from year to year.