Departamento de Biología Animal, Universidad de La Laguna, La Laguna, Tenerife, Spain.
PLoS One. 2010 Sep 23;5(9):e12956. doi: 10.1371/journal.pone.0012956.
Evolutionary studies of insular biotas are based mainly on extant taxa, although such biotas represent artificial subsets of original faunas because of human-caused extinctions of indigenous species augmented by introduced exotic taxa. This makes it difficult to obtain a full understanding of the history of ecological interactions between extant sympatric species. Morphological bill variation of Fringilla coelebs and F. teydea (common and blue chaffinches) has been previously studied in the North Atlantic Macaronesian archipelagos. Character displacement between both species has been argued to explain bill sizes in sympatry. However, this explanation is incomplete, as similar patterns of bill size have been recorded in F. coelebs populations from islands with and without F. teydea.
METHODOLOGY/PRINCIPAL FINDINGS: The discovery of a new extinct species in Tenerife (Canary Islands), here named Carduelis aurelioi n. sp. (slender-billed greenfinch), provides the opportunity to study ancient ecological interactions among Macaronesian finches. To help understand the evolutionary histories of forest granivores in space and time, we have performed a multidisciplinary study combining: (1) morphological analyses and radiocarbon dating (11,460±60 yr BP) of the new taxon and, (2) molecular divergence among the extant finch species and populations in order to infer colonization times (1.99 and 1.09 My for F. teydea and F. coelebs respectively).
CONCLUSION/SIGNIFICANCE: C. aurelioi, F. coelebs and F. teydea co-habited in Tenerife for at least one million years. The unique anatomical trends of the new species, namely chaffinch-like beak and modified hind and forelimbs, reveal that there was a process of divergence of resource competition traits among the three sympatric finches. The results of our study, combined with the presence of more extinct greenfinches in other Macaronesian islands with significant variation in their beak sizes, suggests that the character displacement has influenced patterns of divergence in bill size and shape on other Macaronesian islands as well.
岛屿生物群的进化研究主要基于现存分类群，但由于人类导致的本地物种灭绝以及引入的外来分类群，这些生物群代表了原始动物群的人为子集。这使得很难全面了解现存同域物种之间生态相互作用的历史。Frigilla coelebs 和 F. teydea（普通和蓝雀）的喙形态变异先前在北大西洋马卡罗尼西亚群岛上进行了研究。物种之间的特征替代被认为可以解释同域物种的喙大小。然而，这种解释并不完整，因为在有和没有 F. teydea 的岛屿上，Frigilla coelebs 种群中也记录到了类似的喙大小模式。
方法/主要发现：在特内里费岛（加那利群岛）发现了一个新的灭绝物种，命名为 Carduelis aurelioi n. sp.（细嘴绿雀），为研究马卡罗尼西亚雀类之间的古代生态相互作用提供了机会。为了帮助了解森林食谷者在空间和时间上的进化历史，我们进行了一项多学科研究，结合了：（1）对新分类群进行形态分析和放射性碳测年（11460±60 年 BP），以及（2）对现存雀类物种和种群进行分子分化，以推断出它们的殖民时间（F. teydea 和 F. coelebs 分别为 1.99 和 1.09 百万年）。
结论/意义：C. aurelioi、F. coelebs 和 F. teydea 在特内里费岛共存了至少一百万年。新物种独特的解剖趋势，即雀类的喙和改良的后肢和前肢，表明在这三个同域雀类中，资源竞争特征的分化过程已经开始。我们的研究结果，结合其他马卡罗尼西亚岛屿上更多已灭绝的绿雀的存在以及它们喙大小的显著差异，表明特征替代也影响了其他马卡罗尼西亚岛屿上喙大小和形状的分化模式。
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