2022 Centris pallida head widths

Historical data suggest that human climate and landscape modifications have caused many bee species to decline in body size. Larger-bodied bee species with narrow phenological and dietary breadth are most prone to declines in body size over time, potentially due to temperature increases during development or declines in resource allocation during development. This may be especially true in solitary, desert-adapted species that are vulnerable to climate change – such as Centris pallida (Hymenoptera: Apidae). In addition, body size changes in species with size-linked behaviors could threaten the prevalence of certain behavioral phenotypes long-term. C. pallida (Hymenoptera: Apidae) are large-bodied solitary bees with narrow phenological and dietary breadth found in the Sonoran Desert. Males use alternative reproductive tactics (ARTs) and are dimorphic in both morphology and behavior. Large-morph males are fixed on a patrolling and fighting-based mate location strategy, while small-morph m...