Data from: Temperature-related natural selection in a wind-pollinated tree across regional and continental scales

Adaptive genetic variation is a key factor in evolutionary biology, but the detection of signatures of natural selection remains challenging in non-model organisms. We used a genome scan approach to detect signals of natural selection in the Black alder (Alnus glutinosa), a widespread wind-pollinated tree. Gene flow through pollen dispersal is believed to be high in this species, and we therefore expected to find a clear response to natural selection. In combination with two different landscape genetic approaches, we determined which environmental variables were most associated with the inferred selection. This analysis was performed on a regional scale (northern Belgium) and on a continental scale (Europe). Because climate-related differences are much more pronounced at the continental scale, we expected to find more selection-sensitive genetic markers across Europe than across northern Belgium. At both spatial scales a substantial number of genetic loci were considered outliers, with respect to neutral expectations, and were therefore identified as selective. Based on results from our combined approach, four putative selective loci (or 2.5 %) were recovered with high statistical support. Although these loci seemed to be associated with different environmental variables, they were mainly temperature-related. Our study demonstrates that the use of complementary methods in landscape genetics allows the discovery of selective loci which otherwise might stay hidden. In combination with a genome scan, the selective loci can be verified and the nature of the selection pressure can be identified.适应性遗传变异是进化生物学的核心研究要素之一，但在非模式生物（non-model organism）中检测自然选择的信号仍存在较大挑战。我们采用基因组扫描（genome scan）方法，针对广泛分布的风媒林木欧洲桤木（Alnus glutinosa）开展自然选择信号检测。该物种被认为具备较高的花粉传播基因流（gene flow），因此我们预期能够观测到明确的自然选择响应信号。结合两种不同的景观遗传学（landscape genetics）分析方法，我们明确了与推断得到的选择作用关联度最高的环境变量。本分析分别在区域尺度（比利时北部）与大陆尺度（欧洲）两个空间尺度下开展。由于气候相关差异在大陆尺度上更为显著，我们预期在欧洲范围内相较于比利时北部，能够发现更多对选择作用敏感的遗传标记（genetic marker）。在两个空间尺度下，均有大量遗传位点（genetic locus）相较于中性进化预期呈现离群特征，因此被鉴定为受选择位点。基于联合分析的结果，我们以较高的统计学支持度筛选出4个推定受选择位点，占总检测位点的2.5%。尽管这些位点看似与不同的环境变量相关，但它们主要与温度因素相关联。本研究证实，在景观遗传学研究中采用互补性分析方法，能够发现原本可能被遗漏的受选择位点。结合基因组扫描方法，可对这些受选择位点进行验证，并明确选择压力的作用本质。