When hybridization or other forms of lateral gene transfer have occurred, evolutionary relationships of species are better represented by phylogenetic networks than by trees. While inference of such networks remains challenging, several recently proposed methods are based on quartet concordance factors -- the probabilities that a tree relating a gene sampled from the species displays the possible 4-taxon relationships. Building on earlier results, we investigate what level-1 network features are identifiable from concordance factors under the network multispecies coalescent model. We obtain results on both topological features of the network, and numerical parameters, uncovering a number of failures of identifiability related to 3-cycles in the network.

翻译：当杂交或其他形式的水平基因转移发生时，物种的进化关系更适合用系统发育网络而非树结构来表示。尽管此类网络的推断仍具挑战性，但近期提出的多种方法均基于四元组一致性因子——即从物种中采样的基因所对应的树显示可能的四种分类单元关系的概率。基于已有研究成果，我们探究在网络多物种溯祖模型下，哪些级别-1网络特征可从一致性因子中识别。我们获得了网络拓扑特征与数值参数两方面的结果，并揭示了与网络中三周期结构相关的若干可识别性失败案例。