Admixture in European Populus hybrid zones makes feasible the mapping of loci that contribute to reproductive isolation and trait differences
Admixture in European Populus hybrid zones makes feasible the mapping of loci that contribute to reproductive isolation and trait differences
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DOI：
10.1038/sj.hdy.6800898
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发表时间：
2007-02-01
期刊：
影响因子：
3.8
通讯作者：
Fay, M. F.
中科院分区：
文献类型：
--
作者：
Lexer, C.;Buerkle, C. A.;Fay, M. F.
使用混合的人群来扫描基因组中影响复杂表型性状的染色体片段已被证明是一种强大的分析工具。然而，它在其他生物体中的潜力尚未得到评估。在这里，我们使用DNA微卫星来评估这种方法的可行性，在杂交区的两个成员之间的“模型树”属杨：白杨（白色杨）和白杨（欧洲白杨）。我们分析了这两个物种和中欧杂交区（N = 544染色体）的全基因组的19个多态性DNA微卫星的样本。我们的研究结果表明，两个物种之间的等位基因频率差异是实质性的（平均δ = 0.619 +/- 0.067）。背景连锁不平衡（LD）在亲本基因库的样本是中度的，并应响应采样方案，最大限度地减少漂移和罕见的等位基因。杂交后代的LD随回交世代数的增加而衰减，并接近高世代回交亲本基因库的背景水平。从美洲山杨向白花山杨的渐渗在标记基因座之间变化很大。对于几个标记，来自P. tremula的等位基因相对于中性预期稍微过度代表，而单个基因座表现出对P. tremula基因型的选择的证据。我们解释我们的研究结果在这两个生态不同的杨树品种的混合物映射的潜力，我们验证了一种修改后的方法研究基因型渐变在“马赛克”杂交区。
The use of admixed human populations to scan the genome for chromosomal segments affecting complex phenotypic traits has proved a powerful analytical tool. However, its potential in other organisms has not yet been evaluated. Here, we use DNA microsatellites to assess the feasibility of this approach in hybrid zones between two members of the 'model tree' genus Populus: Populus alba (white poplar) and Populus tremula (European aspen). We analyzed samples of both species and a Central European hybrid zone (N = 544 chromosomes) for a genome-wide set of 19 polymorphic DNA microsatellites. Our results indicate that allele frequency differentials between the two species are substantial (mean delta = 0.619 +/- 0.067). Background linkage disequilibrium (LD) in samples of the parental gene pools is moderate and should respond to sampling schemes that minimize drift and account for rare alleles. LD in hybrids decays with increasing number of backcross generations as expected from theory and approaches background levels of the parental gene pools in advanced generation backcrosses. Introgression from P. tremula into P. alba varies strongly across marker loci. For several markers, alleles from P. tremula are slightly over-represented relative to neutral expectations, whereas a single locus exhibits evidence of selection against P. tremula genotypes. We interpret our results in terms of the potential for admixture mapping in these two ecologically divergent Populus species, and we validate a modified approach of studying genotypic clines in 'mosaic' hybrid zones.