Submitted to: Biological Journal of the Linnean Society, London
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/25/2004
Publication Date: 7/1/2005
Citation: Cane, J.H., Minckley, R.L., Kervin, L., Roulston, T. 2005. Temporally persistent patterns of incidence and abundance in a pollinator guild at annual and decadal scales: the bees of Larrea tridentata. Biological Journal of the Linnean Society, London. 85:319-329.
Interpretive Summary: Assemblages of multiple bee species that vary in taxonomic composition pollinate many flowering plant species. While spatial variation underlies one model for coevolution, temporal persistence among more significant pollinators is a prerequisite for coevolution. We sampled the diverse fauna of bees that visit the dominant desert shrub, creosote bush, across the American Southwest. We found that its more common visitors were reliably found in subsequent years and decades at the same sample sites, but that uncommon bee species were often absent in sequential collections.
Technical Abstract: The geographic mosaic theory of coevolution, posits that reciprocal selection is episodic and confined to populations, rather than persistent and biogeographically extensive. However, little empirical evidence addresses this model's tenets, especially temporal stability of local plant-pollinator interactions. The richly diverse bee guilds of creosote bush (Larrea tridentata) were systematically resampled over 2-5 years at 11 sites across the southwestern USA. Incidence and abundance were compared for survey sites reported 20+2 years earlier as well. Average Morisita-Horn similarities of local guilds was 87% for sequential years and 36% after 20 years. Similarities in taxonomic composition of resampled local bee guilds could be statistically represented as a random assemblage drawn from the regional source pool of bee species possible at Larrea, weighted by regional abundance. At every site, only the more abundant species were typically persistent in local guilds, even after >20 years. In contrast, most species were rare and sporadic both geographically and temporally, attributes that render them numerically inconsequential as pollinators in a local guild. Persistence among abundant bee species in local pollinator