Kryukov Alexey P, Kryukov Kirill A, Collier Kathleen, Fang Bohao, Edwards Scott V
Laboratory of Evolutionary Zoology and Genetics, Federal Scientific Center of the East Asia Terrestrial Biodiversity, Russian Academy of Sciences, Vladivostok 690022, Russia.
Center for Genome Informatics, Bioinformation and DDBJ Center, National Institute of Genetics, 1111 Yata, Mishima 411-8540, Japan.
Curr Zool. 2023 Nov 1;70(5):618-630. doi: 10.1093/cz/zoad048. eCollection 2024 Oct.
Partial separation of a peripheral population may lead to its divergence and, potentially, speciation due to genetic drift followed by selection and geographic isolation. This process may cause taxonomic uncertainty because reproductive isolation in allopatry cannot be verified directly. The two Nearctic allopatric species of magpies (Aves, Corvidae: ) serve as a good example of these problems. The Black-billed magpie is widely distributed in North America, whereas the Yellow-billed Magpie is endemic to a restricted range in California. Their relationships with Palearctic species have been little studied. We obtained complete mitochondrial genomes of both Nearctic magpie species, along with the Eurasian Magpie () and the Oriental Magpie (), 20 mitogenomes in total. Phylogenetic analysis reveals a basal position of , and as a sister clade to the two Nearctic species. and form reciprocal monophyletic subclades, showing recent divergence between and within them. Our data show that the Nearctic magpie lineage diverged from the common ancestor with , with a single migration wave via the Beringia. Within the Nearctic, we hypothesize a peripatric mode of speciation among taxa due to the divergence and separation of the small marginal population in California below the Sierra-Nevada mountains. Diversifying amino acid substitutions in genes along the branch leading to the New World clade may indicate selection for heat-tolerance. Considering the clear phenotypic differences between and , our data, showing their reciprocal monophylies and genetic distinctness, is consistent with the two-species taxonomy.
外围种群的部分隔离可能会由于遗传漂变，随后的选择和地理隔离而导致其分化，并有可能形成物种。这个过程可能会导致分类学上的不确定性，因为异域性生殖隔离无法直接得到验证。两种新北界异域分布的喜鹊（雀形目，鸦科： ）就是这些问题的一个很好的例子。黑嘴喜鹊在北美广泛分布，而黄嘴喜鹊则仅分布于加利福尼亚州的一个受限区域。它们与古北界物种的关系鲜有研究。我们获得了这两种新北界喜鹊物种的完整线粒体基因组，以及欧亚喜鹊（ ）和东方喜鹊（ ）的线粒体基因组，总共20个线粒体基因组。系统发育分析揭示了 的基部位置，以及 作为两个新北界物种的姐妹分支。 和 形成相互单系的子分支，显示出它们之间以及内部的近期分化。我们的数据表明，新北界喜鹊谱系与 的共同祖先发生了分化，通过白令陆桥有一次单一的迁移浪潮。在新北界内部，我们推测由于内华达山脉以南加利福尼亚州小边缘种群的分化和分离， 类群之间存在边域成种模式。导致新世界分支的分支上 基因中多样化的氨基酸替换可能表明对耐热性的选择。考虑到 和 之间明显的表型差异，我们的数据显示它们的相互单系性和遗传独特性，与两物种分类法一致。
