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物种分化恰是因为地貌稳定?
发表日期: 2014-12-15 作者: Brian Tilston Smith 文章来源:《Nature》
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长久以来,人们认为类似安第斯山隆起和亚马逊河形成这样的地貌变化是物种分化的主要驱动力。但最近一项研究表明,物种进化发生在这些变化之后。美国路易斯安那州立大学自然科学博物馆的科研人员发现时间和物种的迁移能力在其进化中扮演了更重要的角色。相关论文发表在近日的《自然》上。

学过生物的人都会认识一种鸟类达尔文雀,它们是一群近缘的雀鸟,但为了适应不同的生存环境,进化出了不同的生物特征:喙大小不一,有些习性也不大一样。这种差异成为物种进化理论的经典例证。

该研究同样也从鸟类着手。论文的作者之一罗伯·布拉姆菲尔德教授表示:南美鸟类丰富的多样性往往被归因于地质年代上地貌的变化,但是我们的研究表明,长时间的地貌稳定性更加重要。

据物理学家组织网近日报道,布拉姆菲尔德和其同事在生物多样性最丰富的新热带地区研究了27种鸟类的谱系,新热带地区从墨西哥南部经中美洲一直延伸到巴西南部,还包括亚马逊热带雨林。

我们对许多鸟类谱系进行了深入、详细地取样研究,对这些物种何时、怎样形成有了更加清晰和广泛的认识。基因数据显示这里有过多次物种分化,随着时间推移,在整个安第斯山脉地区发生929次这样的分化。这表明安第斯山脉的形成并非物种分化的主因,它其实是一种半渗透屏障,对物种分化起到间接影响。

他们接着将目光投向历史和生态环境的影响,结果发现,某一物种在其栖息地呆的时间越长,越可能分散和分化;相应的,一个物种越少迁徙,他们越可能分化。具体来说,相比那些栖息于开阔森林之上的鸟类,被局限于森林地面的鸟类展现出了显著的高度多样性。也就是说,如果一个物种无法在一固定栖息地生活足够久,可能根本没有机会进化。

我们的研究认为,对景观地貌的人为改造会打断物种进化进程。布拉姆菲尔德说。(来源:生物360

 

The drivers of tropical speciation

 

Abstract  Since the recognition that allopatric speciation can be induced by large-scale reconfigurations of the landscape that isolate formerly continuous populations, such as the separation of continents by plate tectonics, the uplift of mountains or the formation of large rivers, landscape change has been viewed as a primary driver of biological diversification. This process is referred to in biogeography as vicariance. In the most species-rich region of the world, the Neotropics, the sundering of populations associated with the Andean uplift is ascribed this principal role in speciation. An alternative model posits that rather than being directly linked to landscape change, allopatric speciation is initiated to a greater extent by dispersal events, with the principal drivers of speciation being organism-specific abilities to persist and disperse in the landscape. Landscape change is not a necessity for speciation in this model. Here we show that spatial and temporal patterns of genetic differentiation in Neotropical birds are highly discordant across lineages and are not reconcilable with a model linking speciation solely to landscape change. Instead, the strongest predictors of speciation are the amount of time a lineage has persisted in the landscape and the ability of birds to move through the landscape matrix. These results, augmented by the observation that most species-level diversity originated after episodes of major Andean uplift in the Neogene period, suggest that dispersal and differentiation on a matrix previously shaped by large-scale landscape events was a major driver of avian speciation in lowland Neotropical rainforests.

原文链接:http://www.nature.com/nature/journal/v515/n7527/pdf/nature1687.pdf

 

 


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