The Ground Tit (Pseudopodoces humilis) has lived on the Qinghai-Tibet Plateau for ∼5.7 My and has the highest altitudinal distribution among all parids. This species has evolved an elongated beak in response to long-term selection imposed by ground-foraging and cavity-nesting habits, yet the genetic basis for beak elongation remains unknown. Here, we perform genome-wide analyses across 14 parid species and identify 25 highly divergent genomic regions that are significantly associated with beak length, finding seven candidate genes involved in bone morphogenesis and remolding. Neutrality tests indicate that a model allowing for a selective sweep in the highly conserved COL27A1 gene best explains variation in beak length. We also identify two nonsynonymous fixed mutations in the collagen domain that are predicted to be functionally deleterious yet may have facilitated beak elongation. Our study provides evidence of adaptive alleles in COL27A1 with major effects on beak elongation of Ps. humilis.

中文翻译：

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比较基因组学揭示了高海拔鸣禽中喙形态学位点的进化。

地面山雀（Pseudopodoces humilis）在青藏高原上的生存时间约为5.7 My，在所有幼体中的海拔分布最高。该物种响应地面觅食和巢巢习性的长期选择而进化出细长的喙，但喙延伸的遗传基础仍然未知。在这里，我们对14种parid物种进行了全基因组分析，并确定了25个高度分化的基因组区域，这些区域与喙的长度显着相关，发现了7个与骨骼形态发生和重塑有关的候选基因。中性测试表明，该模型允许在高度保守的COL27A1中进行选择性扫描基因最能解释喙长的变化。我们还确定了胶原蛋白域中的两个非同义的固定突变，这些突变被预测为功能有害，但可能促进了喙的伸长。我们的研究提供了在COL27A1中具有适应性等位基因的证据，对Ps的喙伸长有重要影响。谦卑。