Climate-associated shifts in color and body size for a tropical bee pollinator

Abstract

Habitat degradation and climatic changes are causing declines in bee populations, which in turn threaten wild plant reproductive success and the global food supply. We examined spatial and temporal variation in traits that may influence the way bees respond to environmental changes. For a color polymorphic species, we characterized proportions of three morphs and measured body size of individuals within sites of varying elevation over an 11-year sampling period. We found climate-associated variation in both color and body size, as well as temporal shifts in these traits that were associated with climatic conditions of sites. The proportion of bees that were red-orange increased relative to two other color morphs. Body size increased over time, and it increased more at drier sites. These results suggest that precipitation may be an important driver of trait shifts in tropical bees and motivate investigations of natural selection on color and body size due to differential climatic tolerances.