Climatic variation across a latitudinal gradient affect phenology and group size, but not social complexity in small carpenter bees

Abstract

Greater social complexity at lower latitudes has been observed in a variety of arthropods from termites to spiders. Social behavior in the small carpenter bees, Ceratina, has been shown to vary widely both between species and across geographic range. Our goal was to determine how social plasticity of three populations of Ceratina species, C. calcarata and C. strenua, vary across a latitudinal gradient. The longer rearing season in the south did not result in two separate brood rearing periods, but instead increased brood production of a single brood with a higher female sex bias. The social structure of nests remained stable across both species’ ranges: mothers exhibit prolonged parental care and worker dwarf eldest daughters occur among populations and species. This is the first report of worker daughters in C. strenua. The ubiquity of worker daughter production in eastern North American Ceratina suggests that factors outside of climate underlie the early division of labor between the reproductive mother and worker dwarf eldest daughter.