We present a novel phylogenetic approach to infer ancestral ontogenies of shape characters described as landmark configurations. The method is rooted in previously published theoretical developments to analyse landmark data in a phylogenetic context with parsimony as the optimality criterion, in this case using the minimization of differences in landmark position to define not only ancestral shapes but also the changes in developmental timing between ancestor–descendant shape ontogenies. Evolutionary changes along the tree represent changes in relative developmental timing between ontogenetic trajectories (possible heterochronic events) and changes in shape within each stage. The method requires the user to determine the shape of the specimens between two standard events, for instance birth and onset of sexual maturity. Once the ontogenetic trajectory is discretized into a series of consecutive stages, the method enables the user to identify changes in developmental timing associated with changes in the offset and/or onset of the shape ontogenetic trajectories. The method is implemented in a C language program called SPASOS. The analysis of two empirical examples (anurans and felids) using this novel method yielded results in agreement with previous hypotheses about shape evolution in these groups based on non‐phylogenetic analyses.

中文翻译：

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PASOS：一种形状个体发育的系统发育分析方法

我们提出了一种新的系统发育方法来推断被描述为标志性配置的形状特征的祖先个体发育。该方法植根于先前发表的理论发展，以简约为最优标准，在系统发育背景下分析地标数据，在这种情况下，使用地标位置差异的最小化不仅定义祖先形状，还定义祖先之间发育时间的变化-后代形状个体发育。沿着树的进化变化代表个体发育轨迹（可能的异时事件）和每个阶段内形状变化之间的相对发展时间的变化。该方法要求用户确定两个标准事件之间样本的形状，例如出生和性成熟的开始。一旦个体发育轨迹被离散化为一系列连续的阶段，该方法使用户能够识别与形状个体发育轨迹的偏移和/或开始的变化相关的发育时间的变化。该方法是在名为 SPASOS 的 C 语言程序中实现的。使用这种新方法对两个经验实例（无尾猿和猫科动物）的分析产生的结果与先前基于非系统发育分析的关于这些群体形状进化的假设一致。