The genetics of adaptive shape shift in stickleback: Pleiotropy and effect size
The genetics of adaptive shape shift in stickleback: Pleiotropy and effect size
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DOI：
10.1111/j.1558-5646.2007.00259.x
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发表时间：
2008-01-01
期刊：
影响因子：
3.3
通讯作者：
Schluter, Dolph
中科院分区：
文献类型：
--
作者：
Albert, Arianne Y. K.;Sawaya, Sterling;Schluter, Dolph
适应基因的效应量分布尚不清楚（Orr 2005）。在自然选择下发生分化的性状组是由几个多效的大效应基因控制（主基因模型），还是由许多独立作用的小效应基因控制（无穷小模型），还是由一种频率与效应大小成反比的组合控制（几何模型）？为了解决这个问题，我们进行了一套54个位置性状描述两个threespine棘鱼物种的体型：一个祖先的太平洋海洋形式和一个高度衍生的底栖物种栖息在一个地质年轻的湖泊数量性状位点（QTL）的研究。在检测到的26个QTL中，约有一半只影响一个坐标，净效应较小，但几个基因组区域影响形状的多个方面，净效应较大。效应量的分布遵循伽马分布，如考虑检测限时适应的几何模型所预测的。在所有QTL中，性别决定染色体区域的效应最大。祖先的性别二型性是相似的分歧的方向，并在很大程度上消除了淡水适应，这表明性别差异可能提供的选择可以采取行动的变化。几个形状QTL与Eda连锁，Eda是淡水中负责减少侧面盔甲的主效基因。我们的研究结果是一致的几何模型的预测适应。棘鱼的形态进化是由少数几个影响较大且可能分布广泛的基因和多个影响较小的基因共同作用的结果。
The distribution of effect sizes of genes underlying adaptation is unknown (Orr 2005). Are suites of traits that diverged under natural selection controlled by a few pleiotropic genes of large effect (major genes model), by many independently acting genes of small effect (infinitesimal model), or by a combination, with frequency inversely related to effect size (geometric model)? To address this we carried out a quantitative trait loci (QTL) study of a suite of 54 position traits describing body shapes of two threespine stickleback species: an ancestral Pacific marine form and a highly derived benthic species inhabiting a geologically young lake. About half of the 26 detected QTL affected just one coordinate and had small net effects, but several genomic regions affected multiple aspects of shape and had large net effects. The distribution of effect sizes followed the gamma distribution, as predicted by the geometric model of adaptation when detection limits are taken into account. The sex-determining chromosome region had the largest effect of any QTL. Ancestral sexual dimorphism was similar to the direction of divergence, and was largely eliminated during freshwater adaptation, suggesting that sex differences may provide variation upon which selection can act. Several shape QTL are linked to Eda, a major gene responsible for reduction of lateral body armor in freshwater. Our results are consistent with predictions of the geometric model of adaptation. Shape evolution in stickleback results from a few genes with large and possibly widespread effects and multiple genes of smaller effect.