03499nas a2200349   4500008004100000245012600041210006900167260001200236300001400248490000700262520256400269653001202833653001702845653001202862653001602874653001602890653001402906653001402920653001002934653001102944653001002955653001502965653001402980653001102994653001503005653001503020100001903035700001703054700001503071700001903086856004403105       1999                        eng d00aSpatial predictability and resource specialization of bees (Hymenoptera: Apoidea) at a superabundant, widespread resource0 aSpatial predictability and resource specialization of bees Hymen  c1999///  a119 - 1470 v673 aFor reciprocal specialization (coevolution) to occur among floral visitors and their host plants the interactions must be temporally and spatially persistent However, studies repeatedly have shown that species composition and relative abundance off oral visitors vary dramatically at all spatial and temporal scales. We test the hypothesis that, on average, pollen specialist bee species occur more predictably at their floral hosts than pollen generalist bee species. Taxonomic floral specialization reaches its extreme among species of solitary, pollen-collecting bees, yet few studies have considered how pollen specialization by floral visitors influences their spatial constancy. We test this hypothesis using an unusually diverse bee guild that visits creosote bush (Larrea tridentata), the most widespread, dominant plant of the warm deserts of North America. Twenty-two strict pollen specialist and 80 + generalist bee species visit Larrea for its floral resources. The sites we sampled were separated by 0.5 to &gt; 1450 km, and spanned three distinct deserts and four vegetation zones. We found that species of Larrea pollen specialist bees occurred at more sites and tended to be more abundant than generalists. Surprisingly, spatial turnover was high for both pollen specialist and generalist bee species at all distances, and species composition of samples from sites 1-5 km apart varied as much as repeat samples made at single sites. Nevertheless, the pattern of bee species turnover was not haphazard. As distance among sites increased faunal similarity of sites decreased. Faunal similarities among sites within 250 km of each other were generally greater than if randomly distributed over all sites (the null model). No single ecological category of species (widespread, localized, Larrea pollen specialist, floral generalist) accounted for this spatial predictability. Evidently, concordant local distribution patterns of many ecologically diverse species contribute to the non-random spatial pattern. The ecological dominance of creosote bush does not confer obvious ecological advantages to its specialist floral visitors. Spatial turnover is comparable to that found for bee guilds from other biogeographic regions of the world and is not therefore limited to those bee species that inhabit highly seasonal climates, such as deserts. Philopatry and differences in bloom predictability among sites are probably more important causes for spatial turnover of bee species than are interspecific competition for nest sites or floral resources10aApoidea10aBIOGEOGRAPHY10aCLIMATE10aCOEVOLUTION10aCOMPETITION10aCONSTANCY10aEVOLUTION10aGUILD10aLARREA10aMODEL10aOLIGOLECTY10aPHENOLOGY10aPOLLEN10aSPECIATION10aSTATISTICS1 aMinckley, R.L.1 aCane, J., H.1 aKervin, L.1 aRoulston, T.H.  uhttps://apoidea.myspecies.info/node/13802433nas a2200253   4500008004100000245014800041210006900189260001200258300001400270490000700284520167700291653001201968653001601980653002301996653001002019653001102029653001502040653001402055100001702069700001702086700001502103700001702118856004402135       2005                        eng d00aTemporally persistent patterns of incidence and abundance in a pollinator guild at annual and decadal scales: the bees of Larrea tridentata0 aTemporally persistent patterns of incidence and abundance in a p  c2005///  a319 - 3290 v853 aA recent alternative model to conventional coevolution, the geographic mosaic theory of coevolution, posits that reciprocal selection is episodic and local, rather than persistent and spatially extensive. However, little empirical evidence addresses this model’s tenets, in particular the temporal stability of local plant-pollinator interactions. We evaluated this tenet using the richly diverse guild of bees at creosote bush (Larrea tridentata), a generalist plant that hosts many specialist bees. We systematically resampled over 2-5 years at 11 sites across the south-western USA. Incidence and abundance also were compared for survey sites sampled 20 2 years earlier. Average Morisita-Horn faunal similarities of local bee 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 54-68 bee species that could be expected at Larrea, weighted by regional abundance. At every site, only the minority of abundant bee species was typically persistent in local guilds, even after > 20 years. Most bee species in the Larrea guild were chronically uncommon, geographically sporadic and temporally unpredictable, attributes that render them numerically inconsequential as pollinators in their local guild. Persistence among abundant bee species in local pollinator assemblages satisfies one condition by which reciprocal selection could act locally. The well-being of these more abundant core species, and not bee diversity per se, may better characterize the health of such plant-pollinator associations.10aApoidea10aCOMMUNITIES10aECOLOGY-HISTORICAL10aGUILD10aLARREA10aPOLLINATOR10aVARIATION1 aCane, J., H.1 aMinckley, R.1 aKervin, L.1 aRoulston, T.  uhttps://apoidea.myspecies.info/node/106