Phylogenetic position of the presumably extinct slender-billed curlew, <i>Numenius tenuirostris</i>

The high-capacity DNA analysis of museum samples opens new opportunities, associated with the investigation of extinct species evolution. Here, the complete mitochondrial genome of the presumably extinct bird species, the slender-billed curlew <i>Numenius tenuirostris</i> (Charadriiformes: Scolopacidae) is presented. Our results showed that mitochondrial DNA (mtDNA) is 16,705 base pairs (bp) in length and contain 13 protein-coding genes, two rRNA genes, and 22 tRNA genes. The overall base composition of the genome is 30.8% – A, 29.8% – C, 25.4% – T, 14.0% – G, and without a significant GC bias of 43.7%. Phylogenetic analyses based on the cytochrome B (<i>cytB</i>) gene and the whole mtDNA sequences revealed that <i>N. tenuirostris</i> had a close genetic relationship to Eurasian curlew (<i>N. arquata</i>), Far Eastern curlew (<i>N. madagascariensis</i>), and long-billed curlew – <i>N. americanus</i>. Besides, it reveals that <i>Numenius</i> genus is genetically distant from other Scolopacidae taxons. Together, these results provide a clear genetic perspective into the speciation process among the curlew genus members and points to a clear taxonomic position of <i>N. tenuirostris</i>.对馆藏标本的高通量DNA分析（high-capacity DNA analysis）为灭绝物种演化研究开辟了全新机遇。本研究报道了疑似已灭绝鸟类——细嘴杓鹬（<i>Numenius tenuirostris</i>，鸻形目Charadriiformes：鹬科Scolopacidae）的完整线粒体基因组（mitochondrial genome）。研究结果显示，该线粒体DNA（mitochondrial DNA，mtDNA）全长16705个碱基对（base pairs，bp），包含13个蛋白质编码基因（protein-coding genes）、2个核糖体RNA（ribosomal RNA，rRNA）基因以及22个转运RNA（transfer RNA，tRNA）基因。该基因组的整体碱基组成为：A占30.8%、C占29.8%、T占25.4%、G占14.0%，整体GC含量为43.7%，无显著GC偏倚（GC bias）。基于细胞色素B（cytochrome B，cytB）基因及完整线粒体DNA序列的系统发育分析（phylogenetic analyses）显示，细嘴杓鹬（<i>N. tenuirostris</i>）与白腰杓鹬（<i>N. arquata</i>）、远东杓鹬（<i>N. madagascariensis</i>）及美洲长嘴杓鹬（<i>N. americanus</i>）具有较近的亲缘关系。此外，分析结果表明杓鹬属（<i>Numenius</i>）与鹬科其他类群在遗传上存在较远分化。综上，本研究结果为杓鹬属物种的物种形成（speciation）过程提供了清晰的遗传学视角，并明确了细嘴杓鹬（<i>N. tenuirostris</i>）的分类学地位。