Synthesis and concluding remarks
Variation in bee functional traits significantly predicts patterns of community change across a wide range of systems and contexts. As such, this framework has become an increasingly popular tool for predicting species-level consequences of global change. Our review highlights common approaches to morphological trait measurement (e.g., ITD), but also reveals knowledge gaps in bee trait data and terminological inconsistency in classifiers applied to behavioral traits, namely diet breadth, nesting behavior, and sociality. We do not prescribe a particular terminology structure here, but rather emphasize that when authors clearly define terms their data becomes useful beyond its original publication. Increasingly, ecologists have called for the development of ecological trait data standards and the application of open science principles to functional trait research (Gallagher et al., 2020; Keller et al., 2023; Schneider et al., 2019). Our analysis highlights the need for integration of these practices into bee functional ecology research. To promote data reuse, researchers should rigorously define trait terminology and make trait data openly accessible with clear metadata and methodological descriptions. Our template for bee functional trait data sharing, along with the compiled primary data from these studies, represents the first step toward a consolidated database of bee functional traits. Future work toward this aim will promote synthesis across diverse study systems and questions in bee functional ecology.