Traits and functional diversity of a hyperdiverse bee assemblage are linked to aridity

Authors: TURNLEY, BENJAMIN - University Of New Mexico; KAZENEL, MELANIE - University Of New Mexico; WRIGHT, KAREN - West Texas A & M University; Griswold, Terry; WHITNEY, KENNETH - University Of Mexico

Submitted to: Oecologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/19/2025
Publication Date: 6/2/2025
Citation: Turnley, B.D., Kazenel, M.R., Wright, K.W., Griswold, T.L., Whitney, K.D. 2025. Traits and functional diversity of a hyperdiverse bee assemblage are linked to aridity. Oecologia. https://doi.org/10.1007/s00442-025-05732-1.
DOI: https://doi.org/10.1007/s00442-025-05732-1

Interpretive Summary: Bee communities in the desert southwest are exceptionally diverse and their habits also differ greatly. Climate change in the southwestern United States is changing the abundance of these bee species in different ways. The thirty-three bee species that were most common were censused for sixteen years at the Sevilleta National Wildlife Refuge in New Mexico and traits like body size, wing size, face hairiness, body hairiness, and lightness were measured. These traits could affect abundance and survival. The study found that changes in how dry the land is changed different groups of bees. For bees that were active in the spring both more wet and more dry years impacted the bees. Impacts of dry years were greater during the monsoon season.

Technical Abstract: Climate change in the American Southwest is altering the composition of species assemblages. However, the resulting patterns in mean trait values and functional diversity are poorly understood. In this study we focused on two questions: Are community-weighted mean trait values linked with aridity, consistent with the hypothesis that aridification is driving bee assemblage change? Has the functional diversity of the Sevilleta bee assemblage declined with aridity, consistent with the hypothesis that pollination services could be declining? To address these questions, we utilized 16 years of abundance data for 33 focal bee species at the Sevilleta National Wildlife Refuge (NM, USA), combined with measurements of a suite of morphological traits. Our results show that changes in aridity are associated with changes in community-weighted mean (CWM) trait values and functional richness of a hyperdiverse bee assemblage. Most CWM trait values increased towards climate extremes in either direction for the spring assemblage. During the monsoon season, CWM trait values increased with aridity. The functional richness of the Sevilleta bee assemblage increased with aridity across both seasons.