Resolving the Speciation Patterns and Evolutionary History of the Intercontinental Disjunct Genus Corylus (Betulaceae) Using Genome-Wide SNPs

Understanding the underlying mechanisms of species origin, divergence, and distribution patterns of the intercontinental disjunct taxa has long fascinated botanists. Based on 4,894 genome-wide single-nucleotide polymorphism dataset, we present a molecular phylogenetic reconstruction of genus (Betulaceae), which have a disjunct distribution between Eurasia and North America (NA). The aim is to explore the speciation patterns and evolutionary relationships of species by establishing a general phylogenetic framework with extensive sampling. Both the molecular phylogeny inferred from recombination-free dataset and structure analysis support the division of into four major clades (A-D). Recombination tests and hybridization detection reveal extensive recombination and hybridization events among different clades, which have potentially influenced the speciation process of . Divergence time estimation indicates that recent common ancestor (MRCA) of occurred in late Eocene (∼36.38 Ma) and subsequent rapid diversification began during Miocene. Ancestral area reconstruction shows that originated from southwest China. The arrival of two clades (Clades B and C) to NA was well supported by the long distance dispersal crossing the Bering land bridge. The Himalayas, European-Mediterranean area, and other distribution regions are primarily the recipients of dispersal taxa. Vicariance after dispersal plays an important role in speciation.