Abstract
The geological events and climatic fluctuations during the Pleistocene played important roles in shaping patterns of species distribution. However, few studies have evaluated the patterns of species distribution that were influenced by the Yellow River. The present work analyzed the demography of two endemic tree species that are widely distributed along the Yellow River, Tamarix austromongolica and Tamarix chinensis, to understand the role of the Yellow River and Pleistocene climate in shaping their distribution patterns. The most common chlorotype, chlorotype 1, was found in all populations, and its divergence time could be dated back to 0.19 million years ago (Ma). This dating coincides well with the formation of the modern Yellow River and the timing of Marine Isotope Stages 5e-6 (MIS 5e-6). Bayesian reconstructions along with models of paleodistribution revealed that these two species experienced a demographic expansion in population size during the Quaternary period. Approximate Bayesian computation analyses supported a scenario of expansion approximately from the upper to lower reaches of the Yellow River. Our results provide support for the roles of the Yellow River and the Pleistocene climate in driving demographic expansion of the populations of T. austromongolica and T. chinensis. These findings are useful for understanding the effects of geological events and past climatic fluctuations on species distribution patterns.
Highlights
The uplift of the Qinghai-Tibet Plateau (QTP) dramatically changed the topography of Asia, and the direction of flow of the Yellow River system from west to east is closely tied to this uplift
These climatic changes can influence the distribution of species because the distributions of some species migrated during glacial periods, and the species survived in refugia, after which many species re-colonized some areas during the postglacial period[22,23,24]; alternatively, other species persisted and adapted to the changed conditions[25,26], while others became extinct[27]
Tamarix austromongolica and Tamarix chinensis are endemic tree species in China[28]; T. austromongolica is naturally distributed in the upper reaches of the Yellow River, from Qinghai to the ravine region between Shanxi and Shaanxi provinces; T. chinensis, mainly occurs in the lower reaches of the Yellow River
Summary
The uplift of the Qinghai-Tibet Plateau (QTP) dramatically changed the topography of Asia, and the direction of flow of the Yellow River system from west to east is closely tied to this uplift. Lacustrine sporopollen records indicated that wetter conditions progressed from western China to the east during the early Pleistocene[21] These climatic changes can influence the distribution of species because the distributions of some species migrated during glacial periods, and the species survived in refugia, after which many species re-colonized some areas during the postglacial period[22,23,24]; alternatively, other species persisted and adapted to the changed conditions[25,26], while others became extinct[27]. Tamarix is an ancient genus occurring in ancient times in the Mediterranean region[31] These two species can serve as good candidates for investigating the influence of the Yellow River and paleoclimate on patterns of species distribution. To better understand the distribution of these two species, we evaluated the following: (1) the relationship between the divergence time of chlorotypes and the paleoclimate, formation, and evolution of the Yellow River; (2) the demographic history of two Tamarix species using genetic data and species distribution models
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
