Escudero Marcial
Department of Integrative Ecology, Estación Biológica de Doñana (EBD-CSIC), Américo Vespucio sn 41092 Seville, Spain; Department of Plant Biology and Ecology, University of Seville, Av. Reina Mercedes sn 41012 Seville, Spain.
Am J Bot. 2015 Jul;102(7):1108-14. doi: 10.3732/ajb.1500130. Epub 2015 Jul 14.
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Fahrenholz's rule states that common ancestors of extant parasites were parasites of the common ancestors of extant hosts. Consequently, parasite phylogeny should mirror host phylogeny. The smut fungi genus Anthracoidea (Anthracoideaceae) is mainly hosted by species of the genus Carex (Cyperaceae). Whether smut fungi phylogeny mirrors sedge phylogeny is still under debate.•
The nuclear large subunit DNA region (LSU; 57 accessions) from 31 Anthracoidea species and the ITS, ETS, and trnL-F spacer-trnL intron complex from 41 Carex species were used to infer the phylogenetic history of parasites and their hosts using a maximum likelihood approach. Event-based and distance-based cophylogenetic methods were used to test the hypothesis of whether the phylogeny of smut fungi from the genus Anthracoidea matches the phylogeny of the sedge Carex species they host.•
Cophylogenetic reconstructions taking into account phylogenetic uncertainties based on event-based analyses demonstrated that the Anthracoidea phylogeny has significant topological congruence with the phylogeny of their Carex hosts. A distance-based test was also significant; therefore, the phylogenies of Anthracoide and Carex are partially congruent.•
The phylogenetic congruence of Anthracoidea and Carex is partially based on smut fungi species being preferentially hosted by closely related sedges (host conservatism). In addition, many different events rather than only codivergence events are inferred. All of this evidence suggests that host-shift speciation rather than cospeciation seems to explain the cophylogenetic patterns of Anthracoidea and Carex.
研究前提：法伦霍尔茨法则指出，现存寄生虫的共同祖先曾是现存宿主共同祖先的寄生虫。因此，寄生虫系统发育应反映宿主系统发育。黑粉菌属炭疽黑粉菌属（炭疽黑粉菌科）主要寄生于苔草属（莎草科）物种。黑粉菌系统发育是否反映莎草系统发育仍存在争议。
方法：利用来自31种炭疽黑粉菌的核大亚基DNA区域（LSU；57个样本）以及来自41种苔草的ITS、ETS和trnL-F间隔区-trnL内含子复合体，采用最大似然法推断寄生虫及其宿主的系统发育历史。基于事件和基于距离的协同系统发育方法用于检验炭疽黑粉菌属黑粉菌的系统发育是否与其所寄生的苔草属物种的系统发育相匹配这一假设。
结果：基于事件分析并考虑系统发育不确定性的协同系统发育重建表明，炭疽黑粉菌的系统发育与其苔草宿主的系统发育具有显著的拓扑一致性。基于距离的检验也具有显著性；因此，炭疽黑粉菌和苔草的系统发育部分一致。
结论：炭疽黑粉菌和苔草的系统发育一致性部分基于黑粉菌物种优先寄生于亲缘关系较近的莎草（宿主保守性）。此外，推断出许多不同的事件而非仅共分化事件。所有这些证据表明，宿主转移物种形成而非共物种形成似乎可以解释炭疽黑粉菌和苔草的协同系统发育模式。
