How sympatric is speciation in the Howea palms of Lord Howe Island?
How sympatric is speciation in the Howea palms of Lord Howe Island?
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DOI：
10.1111/j.1365-294x.2009.04306.x
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发表时间：
2009-09-01
影响因子：
4.9
通讯作者：
Savolainen, Vincent
中科院分区：
文献类型：
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作者：
Babik, Wieslaw;Butlin, Roger K.;Savolainen, Vincent
豪勋爵岛是塔斯曼海的一个小火山岛，岛上有两种棕榈属的植物，现在被认为是同域物种形成的最有说服力的例子之一，尽管这种观点仍然受到一些作者的质疑。人口遗传和生态数据是必要的，以提供一个更连贯和全面的了解这一新兴的模式系统。在这里，我们分析了这两个物种的丰度，少年招聘，授粉模式和遗传变异和结构的数据。我们发现Howea forsteriana比Howea belmoreana丰富。基于扩增片段长度多态性标记的遗传数据表明，尽管估计的人口普查规模的H。belmoreana是H. forsteriana。物种内的遗传结构是低，虽然一些微弱的隔离距离是可检测的。物种之间的基因流似乎是非常有限的，并限制在早期的一代杂种-只有三个混合的个人，被归类为F2或第一代回交到一个亲本物种，被发现在采样的棕榈树。我们的结论是，物种形成在Howea确实是同域的，虽然在某些严格的定义，它可能被称为parapatric。
The two species of the palm genus Howea (Arecaceae) from Lord Howe Island, a minute volcanic island in the Tasman Sea, are now regarded as one of the most compelling examples of sympatric speciation, although this view is still disputed by some authors. Population genetic and ecological data are necessary to provide a more coherent and comprehensive understanding of this emerging model system. Here, we analyse data on abundance, juvenile recruitment, pollination mode and genetic variation and structure in both species. We find that Howea forsteriana is less abundant than Howea belmoreana. The genetic data based on amplified fragment length polymorphisms markers indicate similar levels of variation in the two species, despite the estimated census population size of H. belmoreana being three times larger than that of H. forsteriana. Genetic structure within species is low although some weak isolation by distance is detectable. Gene flow between species appears to be extremely limited and restricted to early-generation hybrids - only three admixed individuals, classified as F2s or first generation backcrosses to a parental species, were found among sampled palms. We conclude that speciation in Howea was indeed sympatric, although under certain strict definitions it may be called parapatric.