Format: ORAL

Roco Prez-Barrales

Botany Department, University of Granada

Pollination involves the transfer of pollen from anthers to stigmas. Indeed, pollination is a messy process shaped by the fit between flowers and pollinators, the contact with reproductive organs along the body of pollinators, pollinator preferences, and the plants breeding system. In addition, pollination interactions are often generalized, leading co-flowering congeners to share pollinators, creating selective pressures based on reproductive costs. If costly, the evolutionary consequences of pollinator sharing should be reflected in patterns of variation in reproductive organs to reduce interspecific pollination and reproductive interference. Here, I investigate variation in pollinator fit, pollen pick-up, and deposition in allopatric and sympatric populations of Linum suffruticosum with other Linum species. The study aims to understand if floral variation can be attributed to local patterns of pollinator sharing, reducing interspecific pollen transfer. Observations in different localities, floral measurements to measure morphological overlap between species, and quantitative analyses of reproductive costs through interspecific hand pollinations were conducted. Results revealed that the size and identity of the most important pollinator explained floral trait variations. The morphological overlap of L. suffruticosum flowers with co-flowering species varied depending on the identity of the co-flowering species. While post-pollination incompatibility maintains reproductive isolation, conspecific pollen-tube formation decreased after heterospecific pollination. In co-flowering sites, conspecific pollen-tube formation was lower than in single-species localities. Overall, the results suggest that trait variation in L. suffruticosum corresponds to the most important local pollinator, and incomplete pollinator partitioning may lead to interspecific pollination with associated reproductive costs. These costs may drive selection favoring reduced morphological overlap with co-flowering congeners, potentially leading to the evolution of pollination ecotypes.