Diversification, adaptation, and community assembly of the American oaks (Quercus), a model clade for integrating ecology and evolution

Ecologists and evolutionary biologists are concerned with explaining the diversity and composition of the natural world and are aware of the inextricable linkages between ecological and evolutionary processes that maintain the Earth's life support systems. Yet examination of these linkages remains challenging due to the contrasting nature of focal systems and research approaches. Model clades provide a critical means to integrate ecology and evolution, as illustrated by the oaks (genus Quercus), an important model clade, given their ecological dominance, remarkable diversity, and growing phylogenetic, genomic, and ecological data resources. Studies of the clade reveal that their history of sympatric parallel adaptive radiation continues to influence community assembly today, highlighting questions on the nature and extent of coexistence mechanisms. Flexible phenology and hydraulic traits, despite evolutionary stasis, may have enabled adaptation to a wide range of environments within and across species, contributing to their high abundance and diversity. The oaks offer fundamental insights at the intersection of ecology and evolution on the role of diversification in community assembly processes, on the importance of flexibility in key functional traits in adapting to new environments, on factors contributing to persistence of long-lived organisms, and on evolutionary legacies that influence ecosystem function.