Ziermann Janine M, Mitgutsch Christian, Olsson Lennart
Department of Anatomy, Howard University College of Medicine, Washington, District of Columbia.
J Exp Zool B Mol Dev Evol. 2014 Dec;322(8):586-606. doi: 10.1002/jez.b.22566. Epub 2014 Apr 2.
Parsimov is a parsimony-based method for identifying the minimum number of heterochronic event-shifts on all branches of a given phylogenetic framework to explain the developmental sequences seen in the species investigated, and has been used to investigate the evolution of developmental sequences in various animal groups. However, the biological interpretation of the results is difficult not least because Parsimov uses non-independent data resulting from event-pairing as the basis for its analyses. To test the applicability of Parsimov to a large data set, larval cranial muscle development was studied in 15 anurans, three caudates and the Australian lungfish. We analyzed the developmental sequences with Parsimov to investigate: if there are (1) heterochronies on deep branches of a cladogram indicating changes in the ancestral sequences, (2) heterochronies that can be related to larval life-history, and (3) the sensitivity of the analysis to different underlying cladograms. We discovered general patterns of cranial muscle development, such as an anterior-to-posterior gradient, an outside-in pattern and a tendency for cranial muscles to develop from their region of origin toward their insertion. We found most heterochronies on terminal branches and only a few shifts on deep branches in the cladograms indicating changes in the ancestral sequences. No changes could be related to larval life-history. The underlying cladogram clearly influenced the outcome of the analysis. We propose that Parsimov has the potential, combined with other methods, to find evolutionary important changes and to aid the biological interpretation of these changes.
Parsimov是一种基于简约性的方法，用于确定给定系统发育框架所有分支上异时事件转移的最小数量，以解释在所研究物种中观察到的发育序列，并且已被用于研究各种动物类群发育序列的进化。然而，对结果的生物学解释很困难，尤其是因为Parsimov使用事件配对产生的非独立数据作为其分析的基础。为了测试Parsimov对大数据集的适用性，我们研究了15种无尾目动物、3种有尾目动物和澳大利亚肺鱼的幼体颅肌发育。我们用Parsimov分析发育序列以研究：（1）在系统发育树的深层分支上是否存在异时性，表明祖先序列的变化；（2）与幼体生活史相关的异时性；（3）分析对不同基础系统发育树的敏感性。我们发现了颅肌发育的一般模式，如从前向后的梯度、由外向内的模式以及颅肌从其起源区域向其插入点发育的趋势。我们在末端分支上发现了大多数异时性，而在系统发育树的深层分支上只有少数转移，表明祖先序列发生了变化。没有发现与幼体生活史相关的变化。基础系统发育树明显影响了分析结果。我们认为，Parsimov有潜力与其他方法相结合，找到具有进化重要性的变化，并有助于对这些变化进行生物学解释。
