The conservatism of prairie pollinators according to experts and empiricism

Ecological conservatism is a popular concept and tool for assessing the biological consequences of environmental change and degradation. However, conservatism has rarely been applied to insects because the requisite experience for assigning conservatism scores (C values) is generally lacking for large swaths of regional insect diversity. We derived expert and empirical C values for 265 prairie pollinator species in an agriculturally intensive region. Four regional pollinator experts independently assigned species-specific C values based on their field experience. Empirical C values were estimated from exhaustive field observations and fidelity to remnant versus non-remnant prairie sites. Expert and empirical C values were weakly correlated (Spearman's (Formula presented.) 0.14–0.27) but differences were relatively small across the majority (52%–77%) of species. Expert-based (Formula presented.) scores for remnants trended higher than expert-based (Formula presented.) scores for non-remnants but showed considerable overlap and limited statistical separation. Empirical C values were statistically independent of conservation status whereas expert C values trended lower for secure species and higher for at-risk species. These results suggest that expert-based C values can show redundancy with conservation ranks and may struggle to differentiate priority sites for prairie pollinators. We discuss how the advantages of empirical C values may outweigh their limitations and the complex ecology of pollinators. We recommend developing empirical C values to help facilitate pollinator-based site assessment and prioritization in prairie regions.