How past climate changes in the Central Andes shaped plant-pollinator interactions and influenced floral phenotypic...

Selective pressures from pollinators are major drivers of floral trait variation, often leading to local adaptation. While contrasting pollinator assemblages can shape floral morphology, past climate changes may have also influenced present-day geographical patterns in floral phenotypes. Salvia stachydifolia exhibits distinct ecotypes adapted to bees or hummingbirds, yet both pollinator groups are currently widespread across its range, suggesting that present abundances alone cannot explain local adaptation. We inquired whether environmental conditions during the Last Glacial Maximum (LGM) influenced the present distribution of S. stachydifolia pollination ecotypes. To achieve this, we modelled present and past habitat suitability for S. stachydifolia main pollinators in the Central Andes. Our results suggest that environmental conditions during the LGM promoted strong habitat differentiation, resulting in areas more suitable for either bees or hummingbirds, a pattern no longer evident at present. Accordingly, past habitat suitability better predicted the current distribution of bee- and hummingbird-pollinated ecotypes than contemporary conditions. These findings highlight the importance of integrating historical perspectives to understand present-day patterns of local adaptation in plant-pollinator systems.