Stuck on top of a mountain: Consequences of dispersal limitations for alpine diversity

Aim The future of biodiversity in increasingly warmer mountains may be poorly predicted by climate variation if dispersal affects ecological change. We assessed the influence limitations assembly mountaintop communities, focusing on relationship between proxies flight abilities and species diversity insects. Location Cantabrian Mountains, Spain. Taxon Grasshoppers (Orthoptera, Acrididae) bumblebees (Hymenoptera, Apidae, Bombinae). Methods analysed magnitude relative wing length individuals, communities along elevation means phylogenetic multilevel generalized least square models, to assess environmental fit this morphological trait. Then we whether among assemblages affected biotic interchange foothills mountaintops, nearby linear models metrics quantifying dispersal. Results converged evolution shorter wings at higher elevations. effects adaptation scaled community level patterns. Mountaintop were richer (grasshoppers) or shared more with lowlands (bumblebees) when average wingspan their member was larger. composition mountaintops significantly processes richness strongly correlated that than mountains. Main Conclusions These results show a reduction upland insects, role improving reducing beta diversity, dependence from pools foothills. In these settings, can envisage upward movements long-winged will favoured increase nestedness biotas as warms. However, fate inhabitants depend how they tackle novel abiotic pressures, given constraints peak-to-peak displacement.