Format: ORAL

Zeng-Yuan Wu

Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming , Yunnan, China

Urticaceae consists of approximately 54 genera with more than 2000 species, and is widely distributed in tropical regions but less common in temperate regions, with by far the largest concentration of genera and species in tropical Asia. This family has important economic and medicinal value, a full understanding of relationships within this family would help to understand how these ecological assemblages evolved, and also to detect potential new sources of medicinal compounds. However, the infra-familial classification of Urticaceae has been controversial for more than one century, and relationships within it remain poorly known. In this talk, I will introduce some of my studies on the systematics of Urticaceae in the last 10 years based on different molecular markers and research methods. In addition, I will present an in-depth study of the biogeography of Urticaceae Integrated multiple lines of evidence including phylogenetic, molecular-dating, biogeographical, ecological, seed biology and oceanographic data, we found that Urticaceae originated in Eurasia ~69 Ma, followed by 92 LDD events between landmasses. Under experimental conditions, it was demonstrated that seeds of many Urticaceae floated for 220 days, and remained viable after ten months in seawater, long enough for most detected LDD events, according to oceanographic current modeling. Ecological trait analyses indicated that preferences for disturbed habitats might facilitate LDD. Nearly half of all LDD events involved dioecious taxa, so population establishment in dioecious Urticaceae requires multiple seeds, or for occasional selfing to be possible. This work clearly shows that seawater LDD played an important role in shaping the geographic distributions of Urticaceae, providing empirical evidence for Darwins transoceanic dispersal hypothesis.