Laboratory of Evolutionary Entomology, Institute of Biology, University of Neuchâtel, Emile-Argand 11, 2000 Neuchâtel, Switzerland.
Mol Phylogenet Evol. 2012 May;63(2):466-74. doi: 10.1016/j.ympev.2012.01.018. Epub 2012 Feb 8.
Coevolution is among the main forces shaping the biodiversity on Earth. In Eurasia, one of the best-known plant-insect interactions showing highly coevolved features involves the fly genus Chiastocheta and its host-plant Trollius. Although this system has been widely studied from an ecological point of view, the phylogenetic relationships and biogeographic history of the flies have remained little investigated. In this integrative study, we aim to test the monophyly of the five Chiastocheta eco-morphological groups, defined by Pellmyr in 1992, by inferring a mitochondrial phylogeny. We further apply a new approach to assess the effect of (i) different molecular substitution rates and (ii) phylogenetic uncertainty on the inference of the spatio-temporal evolution of the group. From a taxonomic point of view, we demonstrate that only two of Pellmyr's groups (rotundiventris and dentifera) are phylogenetically supported, the other species appearing para- or polyphyletic. We also identify the position of C. lophota, which was not included in previous surveys. From a spatio-temporal perspective, we show that the genus arose during the Pliocene in Europe. Our results also indicate that at least four large-scale dispersal events are required to explain the current distribution of Chiastocheta. Moreover, each dispersal to or from Asia is associated with a host-shift and seems to correspond to an increase in speciation rates. Finally, we highlight the correlation between diversification and climatic fluctuations, which indicate that the cycles of global cooling over the last million years had an influence on the radiation of the group.
共同进化是塑造地球上生物多样性的主要力量之一。在欧亚大陆，最著名的涉及高度共同进化特征的植物-昆虫相互作用之一是涉及蝇属 Chiastocheta 和其宿主植物毛茛属 Trollius。尽管这个系统已经从生态学角度进行了广泛研究，但蝇类的系统发育关系和生物地理历史仍然很少被研究。在这项综合研究中，我们旨在通过推断线粒体系统发育来检验 Pellmyr 于 1992 年定义的五个 Chiastocheta 生态形态群的单系性。我们进一步应用一种新方法来评估（i）不同的分子替代率和（ii）系统发育不确定性对群的时空进化推断的影响。从分类学的角度来看，我们证明只有 Pellmyr 的两个群（rotundiventris 和 dentifera）在系统发育上得到支持，其他物种表现出并系或多系性。我们还确定了 Pellmyr 没有包括在以前的调查中的 C. lophota 的位置。从时空角度来看，我们表明该属起源于上新世的欧洲。我们的结果还表明，至少需要四次大规模的扩散事件来解释 Chiastocheta 的当前分布。此外，每次向亚洲或从亚洲的扩散都与宿主转移有关，似乎与物种形成率的增加相对应。最后，我们强调了多样化和气候波动之间的相关性，这表明过去一百万年的全球冷却周期对该群的辐射有影响。
