Into and out of the tropics: global diversification patterns in a hyperdiverse clade of ectomycorrhizal fungi
Into and out of the tropics: global diversification patterns in a hyperdiverse clade of ectomycorrhizal fungi
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DOI：
10.1111/mec.13506
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发表时间：
2016-01-01
影响因子：
4.9
通讯作者：
Matheny, P. Brandon
中科院分区：
文献类型：
--
作者：
Looney, Brian P.;Ryberg, Martin;Matheny, P. Brandon
外生菌根真菌(ECM)是许多优势乔灌木物种的共生共生体，表现出与大多数大型动植物的纬向多样性梯度相反的生物地理格局。然而，这种模式的进化基础还没有在不同的谱系中得到明确的测试。在这项研究中，我们重建了一个世界性和高度多样性的ECM真菌属Russula的巨型系统发育图，从注释样本中提取样本，并利用GenBank中存储的公开可用序列。对分子操作单元聚类集的元数据进行了检验，以推断该属的分布和植物关联性。这使得我们能够测试热带和温带类群之间多样化模式的差异，以及它们与不同植物谱系的联系如何可能成为多样性的驱动因素。结果表明，红菇属在温带地区物种最丰富，祖先状态重建表明该属在温带地区最初是多样化的。迁入和迁出热带是该属早期进化的特征，自那时以来，这些转变一直很频繁。我们提出了广义多样化比率假说，来解释鲁苏拉的纬度多样性梯度反转模式，因为我们在温带以外的谱系中发现了更高的净多样化比率。与植物伴生的多样化模式支持寄主转换和寄主扩展作为驱动多样化的因素，与松科相关的谱系具有更高的多样化比率，并频繁地过渡到被子植物。
Ectomycorrhizal (ECM) fungi, symbiotic mutualists of many dominant tree and shrub species, exhibit a biogeographic pattern counter to the established latitudinal diversity gradient of most macroflora and fauna. However, an evolutionary basis for this pattern has not been explicitly tested in a diverse lineage. In this study, we reconstructed a mega-phylogeny of a cosmopolitan and hyperdiverse genus of ECM fungi, Russula, sampling from annotated collections and utilizing publically available sequences deposited in GenBank. Metadata from molecular operational taxonomic unit cluster sets were examined to infer the distribution and plant association of the genus. This allowed us to test for differences in patterns of diversification between tropical and extratropical taxa, as well as how their associations with different plant lineages may be a driver of diversification. Results show that Russula is most species-rich at temperate latitudes and ancestral state reconstruction shows that the genus initially diversified in temperate areas. Migration into and out of the tropics characterizes the early evolution of the genus, and these transitions have been frequent since this time. We propose the generalized diversification rate' hypothesis to explain the reversed latitudinal diversity gradient pattern in Russula as we detect a higher net diversification rate in extratropical lineages. Patterns of diversification with plant associates support host switching and host expansion as driving diversification, with a higher diversification rate in lineages associated with Pinaceae and frequent transitions to association with angiosperms.