Data for: Effective population size mediates the impact of pollination services on pollen limitation

Inadequate pollen receipt limits flowering plant reproduction worldwide. Ecological causes of pollen limitation (‘PL’), like pollinator scarcity and low plant abundance, have been a primary focus of research. The genetic diversity of plant populations could impact both quantity and quality components of PL in concert with ecological factors, yet empirical examples are lacking. We evaluated joint effects of ecological factors (flower abundance, pollinator visitation) and genetic effective population size (NE) on PL across 13 populations of a common herb. We used a histological approach with 5504 styles from 1137 flowers to separate quantity and quality components of PL, and link these to reproductive output. NE and pollinator visitation interacted to shape PL, but NE had stronger direct effects. Effectively smaller populations experienced stronger quantity PL, and controlled crosses in a pollinator-free environment revealed that pollen quantity was an intrinsic population-level attribute that increased with NE. Pollinator visitation enhanced pollen quality, but only in effectively larger populations. Quantity and quality PL negatively impacted fruit and seed set, respectively. Results highlight that PL is dictated by plant population genetic diversity in addition to commonly evaluated ecological factors. Efforts to support pollinators will only enhance plant reproduction in genetically diverse plant populations.

Methods
Datasets include field-collected data in natural plant populations on pollinator visitation rates and floral density, data on pollen-pistil interactions from field-collected flowers, population genomic metrics dervied from RAD-Seq data (previously published), and crosses performed in greenhouse conditions.