Riders in the sky (islands): using a mega-phylogenetic approach to understand plant species distribution and coexistence at the altitudinal limits of angiosperm plant life

Aim: Plants occurring on high-alpine summits are generally expected to persist due to adaptations to extreme selective forces caused by the harshest climates where angiosperm life is known to thrive. We assessed the relative effects of this strong environmental filter and of other historical and stochastic factors driving plant community structure in very high-alpine conditions.
Location: European Alps, Écrins National Park, France.
Methods: Using species occurrence data collected from floristic surveys on 15 summits (2,791–4,102 m a.s.l.) throughout the Écrins range, along with existing molecular sequence data obtained from GenBank, we used a mega-phylogenetic approach to evaluate the phylogenetic structure of high-alpine plant species assemblages. We used three nested species pools and two null models to address the importance of species-specific and species-neutral processes for driving coexistence.
Results: Compared with the entire species pool of the study region, alpine summits...