Competition for pollination and isolation from mates differentially impact four stages of pollination in a model grassland perennial

1. Species that persist in small populations isolated by habitat destruction may experience reproductive failure. Self-incompatible plants face dual threats of mate-limitation and competition with co-flowering plants for pollination services. Such competition may lower pollinator visitation, increase heterospecific pollen transfer, and reduce the likelihood that a visit results in successful pollination.

2. To understand how isolation from mates and competition with co-flowering species contribute to reproductive failure in fragmented habitat, we conducted an observational study of a tallgrass prairie perennial, Echinacea angustifolia. We quantified the isolation of focal individuals from mates, characterized species richness and counted inflorescences within 1m radius, observed pollinator visitation, collected pollinators, quantified pollen loads on pollinators and on Echinacea stigmas, and measured pollination success. Throughout the season, we sampled 223 focal plants.

3. We pr...