Strong divergent selection at multiple loci in two closely related species of ragworts adapted to high and low elevations on Mount Etna.
Strong divergent selection at multiple loci in two closely related species of ragworts adapted to high and low elevations on Mount Etna.
复制标题
适应埃特纳火山高海拔和低海拔的两种密切相关的狗舌草物种在多个位点上存在强烈的分歧选择。
DOI：
10.1111/mec.15319
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发表时间：
2020
影响因子：
4.9
通讯作者：
Wong ELY
中科院分区：
文献类型：
--
作者：
Wong ELY
最近分化的物种提供了特别丰富的信息系统，用于研究物种形成和面对基因流维持遗传分化。我们研究了两个密切相关的千里光物种的物种形成，S。 aethnensisandS。 chrysanthemifolius，分别生长在西西里岛埃特纳火山的高海拔和低海拔地区，并在中海拔地区形成混合带。我们使用了新生成的全基因组单核苷酸多态性 (SNP) 数据集，该数据集来自沿着海拔梯度收集的 18 个地点的 192 个个体，以重建可能的物种形成历史，识别高度分化的 SNP，并估计发散选择的强度。我们发现该系统中的物种形成涉及沿基因组的异质和双向基因流，并且物种在过去经历了显着的种群规模变化。此外，我们还发现了物种之间高度差异的 SNP，其中一些位于可能涉及物种之间生态差异（例如光合作用和紫外线响应）的基因中。我们分析了这些 SNP 等位基因频率曲线沿海拔梯度的形状。这些谱系显示出显着变化的巧合和一致性，表明存在多种选择力。据估计，对杂种的选择非常强（0.16-0.78），是文献报道的最高选择之一。整个基因组中强大的累积选择与先前发现的内在不相容性的结合可能共同维持这些物种之间的遗传和表型分化——这表明在研究分歧和物种形成时考虑内在和外在因素的重要性。
Recently diverged species present particularly informative systems for studying speciation and maintenance of genetic divergence in the face of gene flow. We investigated speciation in two closely relatedSeneciospecies,S. aethnensisandS. chrysanthemifolius, which grow at high and low elevations, respectively, on Mount Etna, Sicily and form a hybrid zone at intermediate elevations. We used a newly generated genome‐wide single nucleotide polymorphism (SNP) dataset from 192 individuals collected over 18 localities along an elevational gradient to reconstruct the likely history of speciation, identify highly differentiated SNPs, and estimate the strength of divergent selection. We found that speciation in this system involved heterogeneous and bidirectional gene flow along the genome, and species experienced marked population size changes in the past. Furthermore, we identified highly‐differentiated SNPs between the species, some of which are located in genes potentially involved in ecological differences between species (such as photosynthesis and UV response). We analysed the shape of these SNPs’ allele frequency clines along the elevational gradient. These clines show significantly variable coincidence and concordance, indicative of the presence of multifarious selective forces. Selection against hybrids is estimated to be very strong (0.16–0.78) and one of the highest reported in literature. The combination of strong cumulative selection across the genome and previously identified intrinsic incompatibilities probably work together to maintain the genetic and phenotypic differentiation between these species – pointing to the importance of considering both intrinsic and extrinsic factors when studying divergence and speciation.