@article {1616,
	title = {What governs protein content of pollen: Pollinator preferences, pollen-pistil interactions, or phylogeny?},
	journal = {Ecol.Monog.},
	volume = {70},
	year = {2000},
	month = {2000///},
	pages = {617 - 643},
	abstract = {Pollen ranges from 2.5\% to 61\% protein content. Most pollen proteins are likely to be enzymes that function during pollen tube growth and subsequent fertilization, but the vast range of protein quantity may not reflect only pollen-pistil interactions. Because numerous vertebrate and invertebrate floral visitors consume pollen for protein, protein content may influence floral host choice. Additionally, many floral visitors pollinate their host plants. If protein content influences pollinator visitation, then pollinators are hypothesized to select for increased protein content of host plants. We analyzed or gleaned from the literature crude pollen protein concentrations of 377 plant species from 93 plant families. Using this database, we compared pollen protein concentration with (1) pollination mode, (2) pollen collection by bees, and (3) distance from stigma to ovule, after accounting for phylogeny through paired phylogenetic comparisons and a nested ANOVA including taxonomic rank. We found that pollen protein concentrations were highly conserved within plant genera, families, and divisions. We found that bees did not collect pollen that was unusually rich in protein, whether they pollinated or merely robbed their host plant. Plant species with vibratile pollination systems, which require visitation by pollen-collecting bees in order to transfer pollen, tended to have very protein-rich pollen, but it was not clear whether this was due to plant enhancement of pollinator rewards or to the possession of very small pollen grains. We found that zoophilous species were not statistically richer in pollen protein than anemophilous species after accounting for phylogeny, although the three most species-rich anemophilous clades surveyed were generally poor in protein. Plant genera hosting specialist pollen-collecting bees did not have particularly protein-rich pollen. Both mass of protein per pollen grain and pollen grain volume were correlated with stigma-ovule distance. We suggest that the need for growing pollen tubes probably plays a more important role in determining pollen protein content than rewarding pollinators},
	keywords = {ANEMOPHILY, BUZZ POLLINATION, COEVOLUTION, EVOLUTION, PHYLOGENY, POLLEN, POLLEN TUBE, POLLEN-CHEMISTRY, POLLINATION, POLLINATOR, PROTEIN, STIGMA, VARIATION},
	author = {Roulston,T.H. and Cane, J. H. and Buchmann,S.L.}
}
@article {1607,
	title = {Spatial predictability and resource specialization of bees (Hymenoptera: Apoidea) at a superabundant, widespread resource},
	journal = {Biological Journal of the Linnean Society, London},
	volume = {67},
	year = {1999},
	month = {1999///},
	pages = {119 - 147},
	abstract = {For 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 resources},
	keywords = {Apoidea, BIOGEOGRAPHY, CLIMATE, COEVOLUTION, COMPETITION, CONSTANCY, EVOLUTION, GUILD, LARREA, MODEL, OLIGOLECTY, PHENOLOGY, POLLEN, SPECIATION, STATISTICS},
	author = {Minckley,R.L. and Cane, J. H. and Kervin,L. and Roulston,T.H.}
}
@article {1619,
	title = {The effect of pollen protein concentration on body size in the sweat bee Lasioglossum zephyrum (Hymenoptera : Apiformes)},
	volume = {16},
	year = {2002},
	month = {2002///},
	pages = {49 - 65},
	abstract = {Adult bees and wasps provide all the food their offspring require to grow from egg to adult. For a given diet. offspring body size generally increases with an increase in the amount of food consumed as a larva, but the extent to which body size is influenced by the type of food consumed is poorly known. Pollen ranges from 2-60\% protein among plant species, and bees are extremely efficient at assimilating nitrogen; therefore, it seems likely that either parent bees adjust the size of larval provisions to compensate for differences in pollen protein concentration or bee offspring attain different body size depending on the pollen type(s) consumed as a larva, We presented the generalist sweat bee Lasioglossum zephyrum with pollen diets that differed in protein content and monitored offspring body size during two experiments. In a protein supplementation experiment, diets ranged from 20-66\% protein and consisted of Typha pollen amended with soy protein. On a pollen/soy diet, offspring body size increased 25\% with a shift from 20-37\% protein, but did not increase further at greater protein concentrations, In a multiple pollen experiment, pollen diets ranged from 20-39\% protein and consisted of eight pollens that differed naturally in protein concentration. The largest offspring arose from the most protein-rich pollens, whereas much smaller bees developed on protein-poor pollens, Provision size only predicted offspring size when pollen type, and therefore protein quantity, was considered. Adult foragers did not adjust provision size to compensate for pollen protein, Therefore, offspring body size appears to result from a combination of controlled (provision size) and uncontrolled (pollen quality) factors that arise out of bee foraging decisions},
	keywords = {Apoidea, BEE SIZE, BEHAVIOR-FORAGING, BEHAVIOR-NESTING, Halictidae, LARVAL PROVISIONS, NUTRITION, POLLEN, PROTEIN, SIZE},
	author = {Roulston,T.H. and Cane, J. H.}
}
@article {1618,
	title = {The effect of diet breadth and nesting ecology on body size variation in bees (Apiformes)},
	journal = {Journal of the Kansas Entomological Society},
	volume = {73},
	year = {2000},
	month = {2000///},
	pages = {180 - 193},
	abstract = {Body size in animals influences survival, fecundity, and mating opportunity. For bees, parental provisioning behavior largely controls offspring body size. Because larger offspring of many bee species have fitness advantages, selection on body size should act through selection on parental provisioning behavior and restrict body size variation of each species. Many bet species show great variability in body size, however, which may indicate that adult females are often constrained in their ability to consistently produce large offspring. We compared body size variation within bee species for two life history traits that could influence offspring body size: dietary breadth (specialist or generalist) and nesting habit (ground-nesting or cavity-nesting). We determined the head width (a reliable correlate of body size) of 2276 bees belonging to 31 bee species from five families and calculated the body size variation fur each species. Body size variation, measured as the coefficient of variation in head size, did not differ between pollen specialists (oligoleges) and pollen generalists (polyleges) across 13 pairs of closely-related, sympatric bee species of similar body size. Cavity-nesting species showed significantly greater variation in body size than ground-nesting species, which suggests that the choice of nest cavities utilized may be a more important predictor of offspring body size than parental body size. The cleptoparasite Coelioxys sayi had similar body size variation to one of its hosts, Megachile brevis. The European honey bee, Apis mellifera, showed the least body size variation of any species measured},
	keywords = {APIS, Apoidea, BEE SIZE, BEHAVIOR, BEHAVIOR-NESTING, CLEPTOPARASITE, ECOLOGY, FITNESS, LARVAL PROVISIONS, LIFE HISTORY, MEGACHILE, MORPHOLOGY, OLIGOLECTY, POLLEN, POLYLECTY, SELECTION, SIZE, VARIATION},
	author = {Roulston,T.H. and Cane, J. H.}
}
@article {1617,
	title = {Pollen nutritional content and digestibility for animals},
	journal = {Plant Systematics and Evolution},
	volume = {222},
	year = {2000},
	month = {2000///},
	pages = {187 - 209},
	abstract = {This paper reviews the literature concerning digestion and nutrient content of pollen. Four topics are addressed in detail: 1) The mechanism of pollen digestion by animals; 2) The efficiency of mechanical and digestive removal of pollen content by various animals: 3) Range and taxonomic distribution of pollen nutrients, and 4) Adaptive hypotheses proposed to associate pollen chemistry with pollinator reward. Studies on the mechanism(s) of pollen digestion remain inconclusive, but suggest that differences in digestibility among pollen types may reflect differences in pollen wall porosity, thickness, and composition. Although hummingbirds reportedly digest pollen very poorly, most animals studied, including those that do not regularly consume pollen, can digest 50-100\% of ingested grains. Overlooked and recent research of pollen protein content shows that pollen grains may contain over 60\% protein, double the amount cited in some studies of pollen-feeding animals. Adaptive hypotheses that associate pollen starch and pollen caloric content with pollinator reward remain unsubstantiated when critically viewed through the lens of phylogeny},
	keywords = {Apoidea, BATS, BEHAVIOR-FORAGING, BIRD, DIGESTION, HUMMINGBIRD, PHYLOGENY, POLLEN, POLLEN- ANALYSIS, POLLEN-CHEMISTRY, POLLINATOR, PROTEIN, SUGAR},
	author = {Roulston,T.H. and Cane, J. H.}
}
