Data from: Morphological and molecular evolution and their consequences for conservation and taxonomy in the Le Conte's Thrasher (Toxostoma lecontei)

We evaluated geographic variation and subspecific taxonomy in the Le Conte's Thrasher (Toxostoma lecontei) by analyzing DNA sequences from 16 nuclear loci, one mitochondrial DNA locus, and four study skin characters, and compared these data sets with previously published data on plumage coloration and different mtDNA genes. Morphological support for the southernmost taxon, T. l. arenicola, is relatively weak: multivariate analyses of morphometrics or back coloration do not provide diagnostic support, although one color character differs statistically. However, combined DNA analyses indicate that T. l. arenicola is diagnosable and reciprocally monophyletic, diverging from T. l. lecontei at least 140,000 years ago. Little to no past introgression across a very short geographic distance despite the long period of isolation is strong evidence of independently evolving taxa. We suggest that the lack of morphological divergence in traits related to niche use has prevented the two taxa from invading each other's range. Despite relatively weak morphological differences we suggest that these two deeply divergent lineages merit species status, and we suggest Vizcaino Thrasher for the common name corresponding to T. l. arenicola. The population size of T. l. arenicola is small and the taxon is in need of preservation attention.

本研究针对莱康特嘲鸫（Le Conte's Thrasher，Toxostoma lecontei）的地理变异与亚种分类学问题展开评估，通过分析16个核基因座、1个线粒体DNA（mitochondrial DNA，mtDNA）基因座以及4个剥制标本皮肤性状的DNA序列，并将上述数据集与已发表的羽色及不同线粒体DNA基因相关数据进行比对。针对最南部类群T. l. arenicola的形态学支持证据相对薄弱：尽管有1个颜色性状存在统计学差异，但基于形态测量学或背部羽色的多变量分析并未提供有效的鉴定支持。然而，联合DNA分析结果显示，T. l. arenicola具备可鉴别的特征且互为单系群，其与T. l. lecontei的分化时间至少可达14万年。尽管二者已长期隔离，但在极短的地理距离内几乎未发生过既往的遗传渐渗，这一现象为两类群的独立演化提供了强有力的证据。我们推测，与生态位利用相关的性状未出现形态分化，阻碍了两个类群相互入侵对方的分布范围。尽管二者的形态差异相对微弱，但我们认为这两个分化程度极深的支系应当被提升至物种等级，并建议将对应T. l. arenicola的通用中文名称定为维萨尼奥嘲鸫（Vizcaino Thrasher）。T. l. arenicola的种群规模较小，该类群亟需得到保护关注。