High mountain plant-pollinator interactions: a little known but critical component of fragile ecosystems : the case of the endangered alpine plant Androsace brevis

Climate change is a key threat to biodiversity. It is expected to have strong effects on mountain ecosystems, affecting biodiversity at all levels and leading to modifications of the web of interactions. Phenological and altitudinal shifts in flowering species and arthropods could cause mismatches between plant and pollinator populations that can lead to the extinction of both. Notwithstanding its relevance, little is known about high altitude plant-pollinator interactions. Androsace brevis (Hegetschw.) Ces. (Primulaceae) is a narrow endemic plant flowering immediately after snowmelt. Climate warming represents a serious menace to this species, since the upward shift of its range is almost impossible, due to its occurrence on mountain peaks and ridges. Moreover, an anticipation of its already very early and short flowering period could cause mismatches with pollinators. We investigated the reproductive biology of Androsace brevis and the role of arthropods as pollinators through a multidisciplinary approach involving pollinator exclusion experiments, identification of flower-visiting species and analysis of their behaviour through in-field video recording sessions, and quali-quantitative palynological analyses. Moreover, we conducted preliminary studies to estimate the variability and genetic structure of A. brevis populations to assess the relative importance of cross- and self-pollination. We demonstrated the entomophily of the species and we assessed the ecological and taxonomic diversity of taxa spectrum active on its flowers. A. brevis represents a very early trophic resource for nectar- and pollen-feeding insects and the identified interactions can be regarded as a model for high-altitude taxa threatened by climate change, giving new insights on plant-pollinator interactions in high-mountain environment.