Evolutionary Diversity Peaks at Mid-Elevations Along an Amazon-to-Andes Elevation Gradient

Elevation gradients present enigmatic diversity patterns, with trends often dependent on the dimension of considered. However, focus is patterns taxonomic and interactions between evolutionary factors, such as lineage age, are poorly understood. We combine forest census data a genus level phylogeny representing tree ferns, gymnosperms, angiosperms, an depth 382 million years, to investigate across long tropical montane elevation gradient Amazonian flank Peruvian Andes. find that peaks at mid-elevations contrasts richness, which invariant from low mid-elevation, but then decreases elevation. suggest this trend interacts variation in ages lineages elevation, contrasting distribution younger older lineages. For example, while 53% young (originated by 10 years ago) occur only below ∼1,750 m asl, just 13% old 110 restricted asl. Overall our results support Environmental Crossroads hypothesis, whereby mid-gradient mingling distinct floras creates mid-elevation Andean forests rivals lowlands.