Distribution patterns of orchid bees in xeric and mesic habitats on a tropical mountaintop

Abstract

Most studies evaluating insect communities along climatic gradients in mountain regions have overlooked the relevance of the contrasting effects of xeric and mesic habitats on species distribution and richness. Mesic zones in xeric ecosystems can provide more favorable conditions for the maintenance of some insects, including orchid bees (Apidae, Euglossini), which are known for their high species diversity in humid tropical forests. For the first time, we sought to understand the distribution of Euglossini in xeric and mesic habitats during dry and wet seasons along an elevational gradient in Espinhaço mountains, southeastern Brazil. The study collected 4873 orchid bees from three genera and 14 species. During the wet season, bee richness decreased with elevation in both xeric and mesic habitats. However, during the dry season, there was an increase in both bee richness and abundance at intermediate elevations. In the dry season, lower bee richness and abundance were recorded in xeric habitats compared with mesic habitats. Bee richness and abundance did not differ between the dry and wet seasons for mesic habitats, while lower richness and abundance were recorded in the dry season for xeric habitats. Species composition remained unchanged across habitats, and species turnover was identified as the primary driver of β‐diversity among elevations and seasons. Orchid bees require high temperatures, but they cannot tolerate water stress in xeric habitats during the dry season. This highlights the importance of mesic habitats for maintaining these pollinators, which are essential for ecosystems in savanna and mountainous regions.