摘要The mountains of Southwest China comprise a sig-nificant large mountain range and biodiversity hot-spot imperiled by global climate change.The high species diversity in this mountain system has long been attributed to a complex set of factors,and re-cent large-scale macroevolutionary investigations have placed a broad timeline on plant diversification that stretches from 10 million years ago(Mya)to the present.Despite our increasing understanding of the temporal mode of speciation,finer-scale population-level investigations are lacking to better refine these temporal trends and illuminate the abiotic and biotic influences of cryptic speciation.This is largely due to the dearth of organismal sampling among closely related species and populations,spanning the in-credible size and topological heterogeneity of this region.Our study dives into these evolutionary dy-namics of speciation using genomic and eco-morphological data of Stellera chamaejasme L.We identified four previously unrecognized cryptic spe-cies having indistinct morphological traits and large metapopulation of evolving lineages,suggesting a more recent diversification(～2.67-0.90 Mya),largely influenced by Pleistocene glaciation and biotic fac-tors.These factors likely influenced allopatric spe-ciation and advocated cyclical warming-cooling episodes along elevational gradients during the Pleistocene.The study refines the evolutionary timeline to be much younger than previously im-plicated and raises the concern that projected future warming may influence the alpine species diversity,necessitating increased conservation efforts.