BackgroundMitochondrial markers are widely used as a first approach in determining evolutionary relationships among vertebrate taxa at different hierarchical scales. Cytochrome b and cytochrome oxidase I are among the most common markers; they are particularly useful in phylogeography and species delineation studies. Simulation and empirical studies show that increasing the taxon sampling has a clear and strong effect on the accuracy of the inferred trees and therefore on hypothesized phylogenetic relationships (and eventually in new taxonomic rearrangements); this should be considered in the design of studies. The lizard genus Liolaemus is widely distributed in southern South America and includes more than 250 described species. The number of taxa and the distribution of Liolaemus species/populations makes them a good model for testing different hypotheses in systematics.MethodsWe studied two Liolaemus species, Liolaemus nigroviridis and L. monticola as focal species to evaluate their monophyly and the influence of adding new samples from related taxa in the resulting phylogenies. We performed phylogenetic analyses (maximum likelihood and Bayesian inference) using 141 sequences of the mitochondrial DNA Cytochrome b (cyt-b) of 11 Liolaemus species.ResultsOur study show that using intensive taxon sampling for phylogenetic reconstructions, two species (L. uniformis and L. nitidus) are placed within the clades of the two focal species (L. nigroviridis and L. monticola, respectively).ConclusionsOur study confirms the importance of taxon sampling to infer more accurate phylogenetic relationships, particularly to reveal hidden polyphyly or paraphyly, which may have a strong impact on taxonomic proposals and/or inferring cryptic diversity.

中文翻译：

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分子系统发育分析揭示了分类群采样在隐性多样性中的重要性：Liolaemus nigroviridis 和 L. monticola (Liolaeminae) 作为焦点物种

背景线粒体标记被广泛用作确定不同层次尺度脊椎动物分类群之间进化关系的第一种方法。细胞色素 b 和细胞色素氧化酶 I 是最常见的标志物；它们在系统地理学和物种划分研究中特别有用。模拟和实证研究表明，增加分类单元采样对推断树的准确性具有明显而强烈的影响，因此对假设的系统发育关系（并最终在新的分类学重排中）具有明显而强烈的影响；在设计研究时应考虑到这一点。蜥蜴属 Liolaemus 广泛分布于南美洲南部，包括 250 多种已描述的物种。分类群的数量和 Liolaemus 物种/种群的分布使其成为系统学中检验不同假设的良好模型。 方法我们研究了 Liolaemus nigroviridis 和 L. monticola 两个作为焦点物种的 Liolaemus 物种，以评估它们的单系和添加新样本的影响来自相关分类群的结果系统发育。我们使用 11 个 Liolaemus 物种的线粒体 DNA 细胞色素 b (cyt-b) 的 141 个序列进行了系统发育分析（最大似然和贝叶斯推断）。 . nitidus）被放置在两个焦点物种（分别为 L. nigroviridis 和 L. monticola）的进化枝中。