Existence of biogeographic barriers for the long-term Neogene–Quaternary divergence and differentiation of <i>Koenigia forrestii</i> in the Himalaya–Hengduan Mountains

Abstract The prolonged interplay between orographic and climatic changes creates biogeographic barriers, resulting in the allopatric differentiation of plants Himalaya–Hengduan Mountains. Such consequences have led us to investigate long-term Neogene–Quaternary geo-climatic history Eastern Narrowly distributed populations Koenigia forrestii were sampled (ten populations, 97 individuals) analysed for their genetic architecture, including phylogenetic reconstruction (based on plastome plastid DNA/nuclear regions), molecular dating demography, combination with niche dynamics. We estimated that K. (stem age: 11.39 Mya) diverged into three non-overlapping lineages during periods (5.84–2.57 Mya), Himalaya (EHa) being first most diverse lineage. ‘Isolation by environment’ revealed existence structures significantly affected disparate environment. presence demographic events is well supported Bayesian skyline plot, indicating recent expansion. Hence, lineage divergence mainly triggered heterogeneous environment associated barriers due Tsangpo-Brahmaputra Grand Canyon, Mekong-Salween Divide local mountain systems. Nevertheless, shift adaptation are keys determining dynamics diversification forrestii.