The effect of diet breadth and nesting ecology on body size variation in bees (Apiformes)

Publication Type:Journal Article
Year of Publication:2000
Authors:T. H. Roulston, Cane J. H.
Journal:Journal of the Kansas Entomological Society
Volume:73
Pagination:180 - 193
Date Published:2000///
Keywords:APIS, Apoidea, BEE SIZE, BEHAVIOR, BEHAVIOR-NESTING, CLEPTOPARASITE, ECOLOGY, FITNESS, LARVAL PROVISIONS, LIFE HISTORY, MEGACHILE, MORPHOLOGY, OLIGOLECTY, POLLEN, POLYLECTY, SELECTION, SIZE, VARIATION
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

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