Chromosome-level genome and population genomics reveal demographic history,incomplete divergence and coastal adaptation of Rhododendron simsii var.putuoense in East ChinaOA

Geographical isolation plays a crucial role in species divergence and adaptive evolution(Worsham et al.,2017;Loretán et al.,2020).This phenomenon is especially pronounced in land-sea interactive habitats,where geological shifts and climatic variations have significantly influenced genetic structures and distribution patterns by repeatedly modifying habitat connectivity(Jiang et al.,2021).Land-bridge islands,which extend from continental shelves and experience alternating phases of connection and isolation due to glacially driven sea-level fluctuations,function as natural laboratories for investigating species divergence,gene flow,and ecological adaptation(Jin et al.,2016;Cros et al.,2020).The Zhoushan Archipelago,China''s largest archipelago,located on the northern margin of the subtropical zone,has undergone similar geological dynamics(repeated geological linkages and separations from the mainland),forming a distinct"island-continent disjunct distribution"pattern.This characteristic makes it an ideal system to study plant responses to geographical isolation in East Asia(Zhang et al.,2025).