Speciation on Oceanic Islands: Rapid Adaptive Divergence vs. Cryptic Speciation in a Guadalupe Island Songbird (Aves: Junco)
Speciation on Oceanic Islands: Rapid Adaptive Divergence vs. Cryptic Speciation in a Guadalupe Island Songbird (Aves: Junco)
复制标题
DOI：
10.1371/journal.pone.0063242
复制
发表时间：
2013-05-10
期刊：
影响因子：
3.7
通讯作者：
Mila, Borja
中科院分区：
文献类型：
--
作者：
Aleixandre, Pau;Hernandez Montoya, Julio;Mila, Borja
岛屿种群的进化分化，特别是中性和选择性因素的克里思和相对重要性，是物种形成研究的核心。在岛屿殖民的表型进化的速度可以有很大的不同类群，趋同进化的情况下，可以进一步混淆正确的进化历史的推断。鉴于表型性状的潜在不稳定性，在系统发育框架中分析的岛屿谱系的分子测年提供了一个重要的工具来检验自殖民以来表型分歧的假设。瓜达卢佩junco是唯一的岛屿形式的多态黑眼junco（Junco hyemalis），并分享眼睛和羽毛的颜色与大陆变种，但提出了一个扩大的法案和减少身体大小。在这里，我们使用的mtDNA序列，形态特征和歌曲变量的变化，以测试是否Guadalanjunco进化迅速，最近殖民化的大陆形式的黑眼睛junco，或相反，代表了一个分化良好的“神秘”的血统适应岛屿环境，通过长期隔离，羽毛着色的进化收敛的结果。我们发现，相对于大陆J.hyemalis和J.phaeonotus，岛屿血统的mtDNA差异很大，代表了大约60万年的隔离历史。岛屿血统也显着分化的形态和男性歌曲变量。此外，相反的小海洋岛屿上的多样性损失的预测，我们记录相对较高的水平，单倍型和歌曲单元的多样性瓜达拉哈拉岛，尽管长期隔离在一个非常小的地理区域。与流行的分类学相反，瓜达卢佩junco是一个古老的，分化良好的进化谱系，其在羽毛和眼睛颜色上与大陆容科斯的相似性是由于进化趋同。我们的研究结果证实了偏远岛屿在推动分化和物种形成方面的作用，但也证实了它们作为祖先多样性储存库的潜在作用。
The evolutionary divergence of island populations, and in particular the tempo and relative importance of neutral and selective factors, is of central interest to the study of speciation. The rate of phenotypic evolution upon island colonization can vary greatly among taxa, and cases of convergent evolution can further confound the inference of correct evolutionary histories. Given the potential lability of phenotypic characters, molecular dating of insular lineages analyzed in a phylogenetic framework provides a critical tool to test hypotheses of phenotypic divergence since colonization. The Guadalupe junco is the only insular form of the polymorphic dark-eyed junco (Junco hyemalis), and shares eye and plumage color with continental morphs, yet presents an enlarged bill and reduced body size. Here we use variation in mtDNA sequence, morphological traits and song variables to test whether the Guadalupe junco evolved rapidly following a recent colonization by a mainland form of the dark-eyed junco, or instead represents a well-differentiated "cryptic" lineage adapted to the insular environment through long-term isolation, with plumage coloration a result of evolutionary convergence. We found high mtDNA divergence of the island lineage with respect to both continental J. hyemalis and J. phaeonotus, representing a history of isolation of about 600,000 years. The island lineage was also significantly differentiated in morphological and male song variables. Moreover, and contrary to predictions regarding diversity loss on small oceanic islands, we document relatively high levels of both haplotypic and song-unit diversity on Guadalupe Island despite long-term isolation in a very small geographic area. In contrast to prevailing taxonomy, the Guadalupe junco is an old, well-differentiated evolutionary lineage, whose similarity to mainland juncos in plumage and eye color is due to evolutionary convergence. Our findings confirm the role of remote islands in driving divergence and speciation, but also their potential role as repositories of ancestral diversity.