Phylogenies reveal new interpretation of speciation and the Red Queen
Phylogenies reveal new interpretation of speciation and the Red Queen
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DOI：
10.1038/nature08630
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发表时间：
2010-01-21
期刊：
影响因子：
64.8
通讯作者：
Pagel, Mark
中科院分区：
文献类型：
--
作者：
Venditti, Chris;Meade, Andrew;Pagel, Mark
红皇后（1）描述了一种自然观，其中物种不断进化，但并没有变得更好地适应。这是进化生物学中比较独特的隐喻之一，但从未针对可以预测几乎相同结果的竞争模型对其物种形成以恒定速率发生的主张进行过检验（2），也没有提出任何可能导致恒定速率现象的机制。在这里，我们使用 101 个动物、植物和真菌类群的系统发育来测试针对四个竞争模型的恒定速率主张。系统发育分支长度记录了连续的物种形成事件之间的时间或进化变化。这些模型通过指定因素如何组合以产生物种形成，或通过描述整个树的物种形成速率如何变化来预测这些长度的分布。我们发现，物种形成遵循许多乘法或加法作用的小事件的积累的假设分别在 8% 的树中得到支持，而没有一棵树得到支持。另外 8% 的树木暗示物种形成的概率根据与祖先物种的分化程度而变化，6% 的树木暗示物种形成率因类群而异。相比之下，78% 的树木符合最简单的模型，即新物种从单一事件中出现，每个物种都很罕见，但单独足以引起物种形成。该模型预测了物种形成的恒定速率，并为红皇后提供了新的解释：物种在与日益恶化的环境的竞赛中失败的隐喻被将物种形成与导致生殖隔离的罕见随机事件联系起来的观点所取代。试图了解物种辐射（3）或为什么某些群体拥有更多或更少的物种，应该着眼于一组密切相关的生物体共有的物种形成潜在原因目录的大小，而不是这些原因如何组合。
The Red Queen(1) describes a view of nature in which species continually evolve but do not become better adapted. It is one of the more distinctive metaphors of evolutionary biology, but no test of its claim that speciation occurs at a constant rate(2) has ever been made against competing models that can predict virtually identical outcomes, nor has any mechanism been proposed that could cause the constant-rate phenomenon. Here we use 101 phylogenies of animal, plant and fungal taxa to test the constant-rate claim against four competing models. Phylogenetic branch lengths record the amount of time or evolutionary change between successive events of speciation. The models predict the distribution of these lengths by specifying how factors combine to bring about speciation, or by describing how rates of speciation vary throughout a tree. We find that the hypotheses that speciation follows the accumulation of many small events that act either multiplicatively or additively found support in 8% and none of the trees, respectively. A further 8% of trees hinted that the probability of speciation changes according to the amount of divergence from the ancestral species, and 6% suggested speciation rates vary among taxa. By comparison, 78% of the trees fit the simplest model in which new species emerge from single events, each rare but individually sufficient to cause speciation. This model predicts a constant rate of speciation, and provides a new interpretation of the Red Queen: the metaphor of species losing a race against a deteriorating environment is replaced by a view linking speciation to rare stochastic events that cause reproductive isolation. Attempts to understand species-radiations(3) or why some groups have more or fewer species should look to the size of the catalogue of potential causes of speciation shared by a group of closely related organisms rather than to how those causes combine.