Klingenberg C P
Department of Biological Sciences, University of Alberta, Edmonton, Canada.
Biol Rev Camb Philos Soc. 1998 Feb;73(1):79-123. doi: 10.1017/s000632319800512x.
The connection between development and evolution has become the focus of an increasing amount of research in recent years, and heterochrony has long been a key concept in this relation. Heterochrony is defined as evolutionary change in rates and timing of developmental processes; the dimension of time is therefore an essential part in studies of heterochrony. Over the past two decades, evolutionary biologists have used several methodological frameworks to analyse heterochrony, which differ substantially in the way they characterize evolutionary changes in ontogenies and in the resulting classification, although they mostly use the same terms. This review examines how these methods compare ancestral and descendant ontogenies, emphasizing their differences and the potential for contradictory results from analyses using different frameworks. One of the two principal methods uses a clock as a graphical display for comparisons of size, shape and age at a particular ontogenic stage, whereas the other characterizes a developmental process by its time of onset, rate, and time of cessation. The literature on human heterochrony provides particularly clear examples of how these differences produce apparent contradictions when applied to the same problem. Developmental biologists recently have extended the concept of heterochrony to the earliest stages of development and have applied it at the cellular and molecular scale. This extension brought considerations of developmental mechanisms and genetics into the study of heterochrony, which previously was based primarily on phenomenological characterizations of morphological change in ontogeny. Allometry is the pattern of covariation among several morphological traits or between measures of size and shape; unlike heterochrony, allometry does not deal with time explicitly. Two main approaches to the study of allometry are distinguished, which differ in the way they characterize organismal form. One approach defines shape as proportions among measurements, based on considerations of geometric similarity, whereas the other focuses on the covariation among measurements in ontogeny and evolution. Both are related conceptually and through the use of similar algebra. In addition, there are close connections between heterochrony and changes in allometric growth trajectories, although there is no one-to-one correspondence. These relationships and outline links between different analytical frameworks are discussed.
发育与进化之间的联系近年来已成为越来越多研究的焦点，而异时性长期以来一直是这一关系中的关键概念。异时性被定义为发育过程的速率和时间安排上的进化变化；因此，时间维度是异时性研究的一个重要部分。在过去二十年中，进化生物学家使用了几种方法框架来分析异时性，尽管它们大多使用相同的术语，但在描述个体发育中的进化变化方式以及由此产生的分类方面存在很大差异。本综述考察了这些方法如何比较祖先和后代的个体发育，强调它们的差异以及使用不同框架进行分析可能产生矛盾结果的可能性。两种主要方法之一使用时钟作为图形显示，用于比较特定个体发育阶段的大小、形状和年龄，而另一种方法则通过发育过程的起始时间、速率和停止时间来表征发育过程。关于人类异时性的文献特别清楚地说明了这些差异在应用于同一问题时如何产生明显的矛盾。发育生物学家最近将异时性的概念扩展到发育的最早阶段，并将其应用于细胞和分子尺度。这种扩展将发育机制和遗传学的考虑引入了异时性研究，而异时性研究以前主要基于个体发育中形态变化的现象学特征。异速生长是几个形态特征之间或大小与形状测量之间的协变模式；与异时性不同，异速生长并不明确涉及时间。异速生长研究有两种主要方法，它们在表征生物体形态的方式上有所不同。一种方法基于几何相似性的考虑，将形状定义为测量值之间的比例，而另一种方法则关注个体发育和进化中测量值之间的协变。两者在概念上相关，并且通过使用相似的代数相关联。此外，异时性与异速生长轨迹的变化之间存在密切联系，尽管并非一一对应。本文讨论了这些关系以及不同分析框架之间的概述联系。
