Format: ORAL

Pamela S. Soltis

Florida Museum of Natural History, University of Florida, Gainesville, USA

The North American continent is characterized by striking diversity in climate, geology, and soil, which have together shaped patterns of plant diversity. With nearly 40,000 species of seed plants and 20% of the worlds seed plant flora, North American plant communities differ in species richness, phylogenetic diversity, and their resilience in the face of climate change. Analyses of eco-evolutionary dynamics have demonstrated processes of community assembly and species diversification that have contributed to geographic structure of plant diversity at continental, regional, and local levels. For example, differential patterns of species diversification and temporal impacts of community assembly appear to have led to distinct patterns of phylogenetic diversity in eastern versus western North America. Moreover, biodiversity hotspots were identified in Mesoamerica, central Mexico, California, and Florida, with corresponding centers of endemism in Mexico, the southwestern USA, and the southeastern USA. Ongoing studies are integrating traits, phylogenies, and distributional data to forecast risks and resilience both phylogenetically and regionally in the North American flora. The North American Coastal Plain, a global biodiversity hotspot that encompasses the southeastern USA and extends from Texas to the northeastern USA, is a composite of areas of paleo- and neoendemism, which in some cases correspond to regions of significant habitat heterogeneity. Environmental gradients in temperature and precipitation have shaped plant distributions across the hotspot, producing a patchwork of lineage-based adaptive zones. Many rare lineages converge in Florida, where areas of high and low phylogenetic diversity are in close juxtaposition and regions of high endemicity correspond to key structural features such as ridges and river valleys. These nested analyses at multiple geographic scales promise new perspectives for conservation.