Phylogeography Reveals Geographic and Environmental Factors Driving Genetic Differentiation of Populus sect. Turanga in Northwest China

Abstract

Populus sect. Turanga (hereafter referred to as “Populus”), including Populus euphratica and Populus pruinosa, are the predominant tree species in desert riparian forests in northwestern China. These trees play key roles in maintaining ecosystem balance, curbing desertification, and protecting biodiversity. However, the distribution area of Populus forests has been severely diminished and degraded in recent years due to increased habitat destruction and human activity. Understanding the genetic diversity among Populus individuals and populations is essential for designing conservation strategies, but comprehensive studies of their genetic diversity in northwest China are lacking. Here, we assessed the population structures and genetic diversity of 1,620 samples from 85 natural populations of Populus (59 P. euphratica and 26 P. pruinosa populations) covering all of northwestern China using 120 single nucleotide polymorphism (SNP) markers. Analysis of population structure revealed significant differentiation between these two sister species and indicated that strong geographical distribution patterns, a geographical barrier, and environmental heterogeneity shaped the extant genetic patterns of Populus. Both P. euphratica and P. pruinosa populations in southern Xinjiang had higher genetic diversity than populations in other clades, perhaps contributing to local geographic structure and strong gene flow. Analysis of molecular variance (AMOVA) identified 15% variance among and 85% variance within subpopulations. Mantel tests suggested that the genetic variation among P. euphratica and P. pruinosa populations could be explained by both geographical and environmental distance. The genetic diversity of P. euphratica showed a significant negative correlation with latitude and longitude and a positive correlation with various environmental factors, such as precipitation of warmest quarter and driest month, temperature seasonality, and annual mean temperature. These findings provide insights into how the genetic differentiation of endangered Populus species was driven by geographical and environmental factors, which should be helpful for designing strategies to protect these genetic resources in the future.

Genetic relationships and low diversity among the tea-oil Camellia species in Sect. Oleifera, a bulk woody oil crop in China

“…The above analysis showed that the tea-oil Camellia resources on Hainan Island constitute a special group that differs from all of the tested off-island populations. This difference may be caused by the homogenized habitat conditions on the island (Binks et al, 2019;Gai et al, 2021) as well as the limited hybridization and genetic introgression with off-island tea-oil Camellia resources due to the isolation of the island (Li et al, 2020). Therefore, we suggest that the Hainan tea-oil Camellia resources belong to a special ecological type or variant of C. drupifera.…”

Population Structure, Genetic Diversity and Differentiation of Triplophysa tenuis in Xinjiang Tarim River

“…Previous studies have revealed that geographical distance, ecological or environmental differences can bring about genetic isolation of populations and reduce the rate of successful migration ( Chen and Wang, 2021 ; Gai et al, 2021 ). We found that the WS (Toxkan River) and SF individuals (Kashgar River) differentiated obviously and formed two separate clusters in cluster 1, and the AETS individuals (Yarkant River) differentiated with WLWT (Krakech River) and LF individuals (Yurungkash River) in cluster 2.…”

Phylogeography and Ecological Niche Modeling of the Alashan Pit Viper (Gloydius cognatus; Reptilia, Viperidae) in Northwest China and Adjacent Areas

“…Additionally, the uplift of the Qinghai-Tibetan Plateau (QTP) and global Pleistocene cooling promoted the formation and subsequent evolution of the deserts in North China [26,27]. As such, the desert zone may have acted as a geographic barrier that hindered gene flow among populations, which led to high genetic diversity among the populations and low genetic diversity within populations in arid Northwest China, e.g., [16,[28][29][30][31]. However, the influence of historical climate oscillations on the evolutionary history of endemic animals in this region is poorly understood [32].…”