Vertebrate time-tree elucidates the biogeographic pattern of a major biotic change around the K-T boundary in Madagascar
Vertebrate time-tree elucidates the biogeographic pattern of a major biotic change around the K-T boundary in Madagascar
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DOI：
10.1073/pnas.1112487109
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发表时间：
2012-04-03
影响因子：
11.1
通讯作者：
Vences, Miguel
中科院分区：
文献类型：
--
作者：
Crottini, Angelica;Madsen, Ole;Vences, Miguel
马达加斯加生物群的地理和时间起源长期以来一直是争论的焦点。我们重建了一个时间树，包括几乎所有的本地nonflying和nonmarine脊椎动物的分支存在于岛上，从DNA序列的两个单拷贝的蛋白质编码核基因（BDNF和RAG 1）和一组一致的时间限制。重建计算的自相关或独立的替代率超过分支同意放置在白垩纪至新生代的31个分支的起源。在南美洲有姐妹群的两个分支是最古老的，其次是那些假定的亚洲祖先，他们比非洲祖先的普遍分支要古老得多。始新世之后没有来自亚洲的殖民地，这表明亚洲/印度群体的分散和替代在印度和马达加斯加分离期间和之后不久的相对较短的时期内受到青睐。分支的物种丰富度与它们的年龄相关，但是那些在热带雨林中具有大比例物种多样性的分支的物种丰富度明显更高。这一发现表明，马达加斯加脊椎动物中存在一种持续物种形成的潜在模式，这些进化枝中的适应性多样化加速发生，并成功地辐射到雨林中。
The geographic and temporal origins of Madagascar's biota have long been in the center of debate. We reconstructed a time-tree including nearly all native nonflying and nonmarine vertebrate clades present on the island, from DNA sequences of two single-copy protein-coding nuclear genes (BDNF and RAG1) and a set of congruent time constraints. Reconstructions calculated with autocorrelated or independent substitution rates over clades agreed in placing the origins of the 31 included clades in Cretaceous to Cenozoic times. The two clades with sister groups in South America were the oldest, followed by those of a putative Asian ancestry that were significantly older than the prevalent clades of African ancestry. No colonizations from Asia occurred after the Eocene, suggesting that dispersal and vicariance of Asian/Indian groups were favored over a comparatively short period during, and shortly after, the separation of India and Madagascar. Species richness of clades correlates with their age but those clades that have a large proportion of species diversity in rainforests are significantly more species-rich. This finding suggests an underlying pattern of continuous speciation through time in Madagascar's vertebrates, with accelerated episodes of adaptive diversification in those clades that succeeded radiating into the rainforests.