Stone Graham N, White Sarah C, Csóka György, Melika George, Mutun Serap, Pénzes Zsolt, Sadeghi S Ebrahim, Schönrogge Karsten, Tavakoli Majid, Nicholls James A
Institute of Evolutionary Biology, University of Edinburgh, Edinburgh, UK.
National Agricultural Research and Innovation Centre, Forest Research Institute, Mátrafüred, Hungary.
Mol Ecol. 2017 Dec;26(23):6685-6703. doi: 10.1111/mec.14372. Epub 2017 Nov 18.
Approximate Bayesian computation (ABC) is a powerful and widely used approach in inference of population history. However, the computational effort required to discriminate among alternative historical scenarios often limits the set that is compared to those considered more likely a priori. While often justifiable, this approach will fail to consider unexpected but well-supported population histories. We used a hierarchical tournament approach, in which subsets of scenarios are compared in a first round of ABC analyses and the winners are compared in a second analysis, to reconstruct the population history of an oak gall wasp, Synergus umbraculus (Hymenoptera, Cynipidae) across the Western Palaearctic. We used 4,233 bp of sequence data across seven loci to explore the relationships between four putative Pleistocene refuge populations in Iberia, Italy, the Balkans and Western Asia. We compared support for 148 alternative scenarios in eight pools, each pool comprising all possible rearrangements of four populations over a given topology of relationships, with or without founding of one population by admixture and with or without an unsampled "ghost" population. We found very little support for the directional "out of the east" scenario previously inferred for other gall wasp community members. Instead, the best-supported models identified Iberia as the first-regional population to diverge from the others in the late Pleistocene, followed by divergence between the Balkans and Western Asia, and founding of the Italian population through late Pleistocene admixture from Iberia and the Balkans. We compare these results with what is known for other members of the oak gall community, and consider the strengths and weaknesses of using a tournament approach to explore phylogeographic model space.
近似贝叶斯计算（ABC）是群体历史推断中一种强大且广泛使用的方法。然而，区分不同历史情景所需的计算量常常限制了与那些先验认为更有可能的情景进行比较的集合。虽然这种方法通常是合理的，但它将无法考虑到意外但有充分证据支持的群体历史。我们使用了一种分层竞赛方法，即在第一轮ABC分析中比较情景子集，然后在第二轮分析中比较获胜者，以重建西方古北区橡树瘿蜂Synergus umbraculus（膜翅目，瘿蜂科）的群体历史。我们使用了跨越七个基因座的4233个碱基对的序列数据，来探究伊比利亚、意大利、巴尔干半岛和西亚四个假定的更新世避难群体之间的关系。我们在八个组中比较了对148种替代情景的支持度，每个组包含在给定关系拓扑下四个群体的所有可能重排，有或没有一个群体通过混合建立，以及有或没有一个未采样的“幽灵”群体。我们发现，对于先前为其他瘿蜂群落成员推断出的方向性“走出东方”情景，几乎没有支持。相反，得到最强支持的模型表明，伊比利亚是在更新世晚期第一个与其他群体分化的区域群体，随后是巴尔干半岛和西亚之间的分化，以及通过更新世晚期来自伊比利亚和巴尔干半岛的混合建立意大利群体。我们将这些结果与橡树瘿蜂群落其他成员的已知情况进行比较，并考虑使用竞赛方法探索系统发育地理模型空间时的优缺点。
