Adaptive introgression and maintenance of a trispecies hybrid complex in range-edge populations of Populus
Adaptive introgression and maintenance of a trispecies hybrid complex in range-edge populations of Populus
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DOI：
10.1111/mec.14820
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发表时间：
2018-12-01
影响因子：
4.9
通讯作者：
Keller, Stephen R.
中科院分区：
文献类型：
--
作者：
Chhatre, Vikram E.;Evans, Luke M.;Keller, Stephen R.
在发生在边缘环境的杂交区，从一个物种到另一个物种的基因组背景的适应性渐渗可能构成一种机制，促进适应范围的限制。虽然最近的研究提高了我们的理解广泛分布的树种的适应性基因渗入，很少有人知道这个过程中的种群在物种范围的边缘的动态。我们调查了美国和加拿大落基山脉地区的三个种杨属Tacamahaca组（P. balsamifera，P. angustifolia和P. duccarpa）在其分布边缘的渐渗程度。使用测序基因分型（GBS），我们分析了来自这三个物种的29个异域和同域种群的296个个体的83，000个单核苷酸多态性基因型。我们发现了一个三种混合复杂的范围重叠的整个区域，包括早期以及先进的世代回交杂交，表明经常性的基因流在这个混合复杂。利用基因组无性系分析，我们发现在杂种中23%的基因座处存在非中性渐渗模式的证据，其中47%和8%分别代表来自P. angustifolia和P. balsamifera的过量祖先。基因本体分析表明，这些基因组区域丰富的基因与光周期调节，金属离子运输，氧化还原稳态的维持和细胞壁代谢产物参与调节季节性休眠。我们的研究表明，在范围边缘人群的多物种混合复杂的适应性渐渗的作用，并有影响的理解在混合区，特别是在物种分布的边缘适应的进化动力学。
In hybrid zones occurring in marginal environments, adaptive introgression from one species into the genomic background of another may constitute a mechanism facilitating adaptation at range limits. Although recent studies have improved our understanding of adaptive introgression in widely distributed tree species, little is known about the dynamics of this process in populations at the margins of species ranges. We investigated the extent of introgression between three species of the genus Populus sect. Tacamahaca (P. balsamifera, P. angustifolia and P. trichocarpa) at the margins of their distributions in the Rocky Mountain region of the United States and Canada. Using genotyping by sequencing (GBS), we analysed similar to 83,000 single nucleotide polymorphisms genotyped in 296 individuals from 29 allopatric and sympatric populations of the three species. We found a trispecies hybrid complex present throughout the zone of range overlap, including early as well as advanced generation backcross hybrids, indicating recurrent gene flow in this hybrid complex. Using genomic cline analysis, we found evidence of non-neutral patterns of introgression at 23% of loci in hybrids, of which 47% and 8% represented excess ancestry from P. angustifolia and P. balsamifera, respectively. Gene ontology analysis suggested these genomic regions were enriched for genes associated with photoperiodic regulation, metal ion transport, maintenance of redox homeostasis and cell wall metabolites involved in regulation of seasonal dormancy. Our study demonstrates the role of adaptive introgression in a multispecies hybrid complex in range-edge populations and has implications for understanding the evolutionary dynamics of adaptation in hybrid zones, especially at the margins of species distributions.