Format: ORAL

Jie Liu1

1 CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences

The conservation of endangered plants is a crucial step for the maintenance of biodiversity in a changing world. However, the lack of comprehensive phylogeographic information for most endangered species greatly impedes effective action, especially for species distributed across national borders. Beaked hickory (Carya sinensis), which is endemic to China and Vietnam, part of the Indo-Burma biodiversity hotspot, exemplifies these issues. Here, based on comprehensive field sampling, we used three genomic datasets (i.e. plastid, mitochondrial, and nrDNA) and ecological niche modeling to reveal its genetic diversity, phylogeographic structure, and population history, shedding insights into conservation. Three distinct clades were resolved, i.e. Clade A in Vietnam, Clade B in China, and Clade C covering both countries. Genetic diversity is low at species and within-clade levels, but multiple private haplotypes were observed in each clade. The three clades diverged between 6 and 8 million years ago, making this a far older species than others within Carya, and each likely had a separate glacial refugium. Bottlenecks were detected in all three clades after the LGM, probably driven by the late Pleistocene glacial oscillations, but Clade C experienced a recent (~800 years ago) expansion which might have been anthropogenic. From this, we recommend treating the three clades as distinct conservation units for C. sinensis and propose a precise evidence-based in and ex situ conservation management strategy, as part of a practical transboundary conservation framework. This sets a model for transboundary conservation through joint efforts between nations, for other threatened species using a similar integrative approach.