Ecological differentiation of closely related species has attracted wide attention to explore its evolutionary significance in speciation. Numerous studies using widespread species on or near to the Qinghai-Tibetan Plateau (QTP) have revealed the impact of QTP uplift and Quaternary climate change on the speciation and diversification.
    Researchers from Xishuangbanna Tropical Botanical Garden (XTBG) used two parapatric sister species, Roscoea humeana and R. cautleoides, to test whether ecological speciation was associated with Quaternary climate changes in these taxa. They employed neutral chloroplast DNA and nuclear DNA, and ENMs to test their hypotheses on geology- versus climate-driven divergence between R. humeana and R. cautleoides to illuminate the role of Quaternary climate changes in ecological speciation.
   Phylogeographical data and niche modelling supported the hypothesis that Roscoea humeana and R. cautleoides underwent allopatric divergence and speciation caused by the uplift of QTP during the Neogene. Gene genealogies indicated that Roscoea humeana evolved from R. cautleoides by climate-niche divergence following colonization of high-elevation areas. Molecular estimates of divergence time placed the timing of speciation in the middle to late Quaternary (0.01–1.48 million years).
The species distribution and phylogeographical pattern were inconsistent with a geographical barrier. Niche models and statistical analyses showed significant ecological differentiation. Divergence between R. humeana and R. cautleoides was recent and coincident with Quaternary climate cycles. Ecological niche differentiation within Quaternary refugia may have promoted speciation.
The study provided an additional case to help understand the origin of the extraordinary biodiversity of the Hengduan-Mountain Region.
The study entitled “Ecological divergence of two closely related Roscoea species associated with late Quaternary climate change” has been published online in Journal of Biogeography.

Contact
LI Qingjun Ph.D Principal Investigator
Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303, China
Tel: 86-871-68125332
E-mail: lqj@xtbg.org.cn