Covain Raphaël, Dray Stéphane, Fisch-Muller Sonia, Montoya-Burgos Juan I
Département d'herpétologie et d'ichtyologie, Muséum d'histoire naturelle, 1 route de Malagnou, C.P. 6434, CH-1211 Genève 6, Switzerland.
Mol Phylogenet Evol. 2008 Mar;46(3):986-1002. doi: 10.1016/j.ympev.2007.12.015. Epub 2007 Dec 25.
With the increase of laboratory facilities, molecular phylogenies are playing a predominant role in evolutionary analyses. However, understanding the evolution of morphological traits remains essential for a comprehensive view of the evolution of a group. Here we present a new approach based on co-inertia analysis for identifying characters which variations are dependent to the phylogeny, a prerequisite for analyzing the evolution of characters. Our approach has the advantage of treating the full data set at once, including qualitative and quantitative variables. It provides a graphical output giving the contribution of each variable to the co-structure, allowing a direct discrimination among phylogenetically dependent and independent variables. We have implemented this approach in deciphering the evolution of morphological traits in a highly specialized group of Neotropical catfishes: the Loricariinae. We have first inferred a molecular phylogeny of this group based on the 12S and 16S mitochondrial genes. The resulting phylogeny indicated that the subtribe Harttiini was restricted to the single genus Harttia, and within the subtribe Loricariini, two sister subtribes were distinguished, Sturisomina (new subtribe), and Loricariina. Among Loricariina, the morphological groups Loricariichthys and Loricaria+Pseudohemiodon were confirmed. The co-inertia analysis highlighted a strong relationship between the morphological and the genetic data sets, and identified three quantitative and eight qualitative variables linked to the phylogeny. The evolution of quantitative variables was assessed using the orthogram method and showed a major punctual event in the evolution of the number of caudal-fin rays, and a more gradual pattern of evolution of the number of teeth along the phylogeny. The evolution of qualitative variables was inferred using ancestral states reconstructions and highlighted parallel patterns of evolution in characters linked to the mouth, suggesting co-evolution of the traits for adapting to divergent substrates.
随着实验室设施的增加，分子系统发育在进化分析中发挥着主导作用。然而，对于全面了解一个类群的进化而言，理解形态特征的进化仍然至关重要。在此，我们提出一种基于协惯性分析的新方法，用于识别其变异依赖于系统发育的性状，这是分析性状进化的一个前提条件。我们的方法具有一次性处理完整数据集的优势，包括定性和定量变量。它提供了一种图形输出，显示每个变量对协结构的贡献，从而能够直接区分系统发育依赖变量和独立变量。我们已将此方法应用于解读新热带鲶鱼的一个高度特化类群——甲鲶亚科的形态特征进化。我们首先基于12S和16S线粒体基因推断了该类群的分子系统发育。所得的系统发育表明，哈氏甲鲶族仅限于单属哈氏甲鲶属，在甲鲶族内，区分出了两个姐妹族，即新族斯图里甲鲶族和甲鲶族。在甲鲶族中，确认了甲鲶属和甲鲶属 + 拟半齿甲鲶属的形态类群。协惯性分析突出了形态数据集和遗传数据集之间的紧密关系，并识别出与系统发育相关的三个定量变量和八个定性变量。使用正视图法评估定量变量的进化，结果显示尾鳍鳍条数目的进化中有一个主要的 punctual 事件，并且沿着系统发育，牙齿数目的进化模式更为渐进。使用祖先状态重建推断定性变量的进化，并突出了与口部相关性状的平行进化模式，表明这些性状为适应不同底物而共同进化。
