Phylogenomics, biogeography, and evolution of morphology and ecological niche of the eastern Asian–eastern North American Nyssa (Nyssaceae)

• Published in: Journal of systematics and evolution : JSE 2020-09, Vol.58 (5), p.571-603
• Main Authors: Zhou, Wenbin, Xiang, Qiu‐Yun (Jenny), Wen, Jun
• Format: Article
• Language: English
• Subjects: Biogeography; Biological evolution; Dating; Disjunction; Dispersion; Divergence; Diversification; eastern Asian–eastern North American–Central American disjunction; Ecological niches; Eocene; Evolution; evolution of morphology and ecological niche; Flora; Fluidigm sequencing; Fossils; gene tree/species tree; Geographical distribution; Land bridges; Macroevolution; Morphology; Neogene; Niches; Nyssa; Nyssaceae; Oligocene; Paleocene; Paleogene; phylogenomics; Phylogeny; Refugia; Species; Species extinction
• ISSN: 1674-4918; 1759-6831
• DOI: 10.1111/jse.12599

Nyssa (Nyssaceae, Cornales) represents a classical example of the well‐known eastern Asian–eastern North American floristic disjunction. The genus consists of three species in eastern Asia, four species in eastern North America, and one species in Central America. Species of the genus are ecologically important trees in eastern North American and eastern Asian forests. The distribution of living species and a rich fossil record of the genus make it an excellent model for understanding the origin and evolution of the eastern Asian–eastern North American floristic disjunction. However, despite the small number of species, relationships within the genus have remained unclear and have not been elucidated using a molecular approach. Here, we integrate data from 48 nuclear genes, fossils, morphology, and ecological niche to resolve species relationships, elucidate its biogeographical history, and investigate the evolution of morphology and ecological niches, aiming at a better understanding of the well‐known EA–ENA floristic disjunction. Results showed that the Central American (CAM) Nyssa talamancana was sister to the remaining species, which were divided among three, rapidly diversified subclades. Estimated divergence times and biogeographical history suggested that Nyssa had an ancestral range in Eurasia and western North America in the late Paleocene. The rapid diversification occurred in the early Eocene, followed by multiple dispersals between and within the Erasian and North American continents. The genus experienced two major episodes of extinction in the early Oligocene and end of Neogene, respectively. The Central American N. talamancana represents a relic lineage of the boreotropical flora in the Paleocene/Eocene boundary that once diversified in western North America. The results supported the importance of both the North Atlantic land bridge and the Bering land bridge (BLB) for the Paleogene dispersals of Nyssa and the Neogene dispersals, respectively, as well as the role of Central America as refugia of the Paleogene flora. The total‐evidence‐based dated phylogeny suggested that the pattern of macroevolution of Nyssa coincided with paleoclimatic changes. We found a number of evolutionary changes in morphology (including wood anatomy and leaf traits) and ecological niches (precipitation and temperature) between the EA–ENA disjunct, supporting the ecological selection driving trait evolutions after geographic isolation. We also demonstrated challenge