Ocean currents play a significant role in driving the long-distance dispersal (LDD), spatial distribution and phylogeographic patterns of many organisms. Integrating phylogeographic analyses and mechanistic ocean current modelling can provide novel insights into the evolutionary history of terrestrial littoral species but has been rarely applied in this context. We focused on a group of Cycas that have buoyant seeds and occupy coastal habitats. By integrating evidence from mechanistic simulations and whole plastomic data, we examined the role of ocean circulation in shaping the phylogeography of these Cycas species. Plastomes of the studied Cycas species showed extreme conservatism, following a post-Pleistocene divergence. Phylogenies revealed three subclades, corresponding to the Pacific Ocean, Sunda Shelf and Indian Ocean. The ocean modelling results indicate that hotspots of seed stranding coincide well with the contemporary distribution of the Cycas species and that drifting trajectories from the three subclades are largely confined to separate regions. These findings suggest that ocean current systems, by driving long-distance dispersal, have shaped the distribution and phylogeography for Cycas with buoyant seeds. This study highlights how the combination of genomic data and ocean drift modelling can help explain phylogeographic patterns and diversity in terrestrial littoral ecosystems.
Bibliographical noteFunding Information:
We would like to thank three anonymous reviewers for their thoughtful comments and constructive suggestions towards improving our manuscript. This work is supported by the Biodiversity Survey, Observation and Assessment of the Ministry of Ecology and Environment, China (2019HJ2096001006), the National Natural Science Foundation of China (31900184, 31800191 and 32000169), the West Light Foundation of the Chinese Academy of Sciences (Y8246811W1), and Natural Science Foundation of Yunnan Province (202001AT070072). We thank James Shevock and Maia M. Jones for their linguistic assistance during the preparation and revision of this manuscript.
© 2021 The Authors. New Phytologist © 2021 New Phytologist Foundation
- long-distance dispersal
- ocean drift modelling