Format: ORAL

James Boyko12 Thais Vasconcelos1

1 Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, USA 2 Michigan Institute of Data Science, University of Michigan, Ann Arbor, USA

The remarkable diversity of angiosperm species have prompted a search for universal drivers that modulate rates of speciation and extinction across this clade. To date, most attempts to define differences in diversification have correlated diversification rates with the presence or absence of a discrete trait. However, an often overlooked explanation is that the evolutionary lability, here defined as the rates of trait change, is a better predictor of the diversification dynamics than the observed traits themselves. This hypothesis, first proposed half a century ago in the context of biome shifts, is based on the idea that the capacity to adapt to environmental changes is the key element defining angiosperm diversification dynamics. Thus, rather than relying on single phenotypic descriptors, we test whether the propensity of change between biomes is significantly correlated with lineage speciation and extinction rates. We test this hypothesis using a phylogenetic dataset of 51 angiosperm clades including 10,636 species in closed-canopy, 4,818 in open-canopy and 3,921 widespread across both biomes. We find that trait lability is frequently associated with higher rates of both speciation and extinction. Additionally, we find that transition rates tend to be faster from open to closed-canopy biomes, contrary to prevailing ideas in the field that lineages occurring in open-canopy biomes tend to emerge from closed-canopy ones. We propose that looking at lability rather than single traits, in angiosperms and other organisms, may provide a more comprehensive and dynamic understanding of biodiversity patterns. This shift in focus from static traits to dynamic evolutionary processes offers new insights into how biodiversity is generated and maintained.