Fan Xingke, Yan Xia, Qian Chaoju, Awuku Ibrahim, Zhao Pengshu, Liao Yuqiu, Li Zhijun, Li Xinrong, Ma Xiao-Fei
Key Laboratory of Ecological Safety and Sustainable Development in Arid Lands Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences Lanzhou China.
Key Laboratory of Stress Physiology and Ecology in Cold and Arid Regions, Department of Ecology and Agriculture Research, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences Lanzhou China.
Ecol Evol. 2024 Aug 29;14(9):e70199. doi: 10.1002/ece3.70199. eCollection 2024 Sep.
Hybrid speciation plays an important role in species diversification. The establishment of reproductive isolation is crucial for hybrid speciation, and the identification of diverse types of hybrids, particularly homoploid hybrid species, contributes to a comprehensive understanding of this process. is a constructive shrub widespread in arid Central Asia. Previous studies have inferred that the populations in the Gurbantunggut Desert (GuD) originated from homoploid hybridizations between its eastern and western lineages and may have evolved into an incipient species. To further elucidate the genetic composition of different hybrid populations and to determine the species boundary of this hybrid lineage, we investigated the overall phylogeographic structure of based on variation patterns of five cpDNA and one nrITS sequences across 32 populations. Phylogenetic analyses demonstrated that within the GuD lineage, the Wuerhe population evolved directly from ancestral lineages, whereas the others originated from hybridizations between the eastern and western lineages. PCoA and genetic barrier analysis supported the subdivision of the GuD lineage into the southern (GuD-S) and northern (GuD-N) groups. Populations in the GuD-S group had a consistent genetic composition and the same ancestral female parent, indicating that they belonged to a homoploid hybrid lineage. However, the GuD-N group experienced genetic admixture of the eastern and western lineages on nrITS and cpDNA, with some populations inferred to be allopolyploid based on ploidy data. Based on cpDNA haplotypes, BEAST analyses showed that the GuD-S and GuD-N groups originated after 0.5 Ma. Our results suggest that multiple expansions and contractions of GuD, driven by Quaternary climatic oscillations and the Kunlun-Yellow River tectonic movement, are important causes of the complex origins of populations in northern Xinjiang. This study highlights the complex origins of the Junggar Basin flora and the underappreciated role of hybridization in increasing its species diversity.
杂交物种形成在物种多样化中起着重要作用。生殖隔离的建立对于杂交物种形成至关重要，识别不同类型的杂种，特别是同源多倍体杂交物种，有助于全面理解这一过程。[物种名称]是一种广泛分布于干旱中亚地区的建设性灌木。先前的研究推断，古尔班通古特沙漠（GuD）中的[物种名称]种群起源于其东部和西部谱系之间的同源多倍体杂交，并且可能已经进化为一个初始物种。为了进一步阐明不同杂交种群的遗传组成并确定这个杂交谱系的物种边界，我们基于32个种群的五个叶绿体DNA（cpDNA）和一个核糖体内部转录间隔区（nrITS）序列的变异模式，研究了[物种名称]的整体系统地理学结构。系统发育分析表明，在GuD谱系中，乌尔禾种群直接从祖先谱系进化而来，而其他种群则起源于东部和西部谱系之间的杂交。主坐标分析（PCoA）和遗传屏障分析支持将GuD谱系细分为南部（GuD-S）和北部（GuD-N）组。GuD-S组的种群具有一致的遗传组成和相同的母系祖先，表明它们属于同源多倍体杂交谱系。然而，GuD-N组在nrITS和cpDNA上经历了东部和西部谱系的遗传混合，根据倍性数据推断一些种群为异源多倍体。基于cpDNA单倍型，贝叶斯进化分析采样树（BEAST）分析表明，GuD-S和GuD-N组在0.5百万年前之后起源。我们的结果表明，由第四纪气候振荡和昆仑-黄河构造运动驱动的GuD多次扩张和收缩，是新疆北部[物种名称]种群复杂起源的重要原因。这项研究突出了准噶尔盆地植物区系的复杂起源以及杂交在增加其物种多样性方面未得到充分认识的作用。
