Klingenberg Christian Peter, Spence John R
Department of Entomology, University of Alberta, Edmonton, Alberta, T6G 2E3, Canada.
Evolution. 1993 Dec;47(6):1834-1853. doi: 10.1111/j.1558-5646.1993.tb01273.x.
Heterochrony and allometry both deal with evolutionary modifications of ontogenies. Although data about both morphology and age are required to identify heterochronic processes, age data are not needed to study allometry. Using a simple graphical model, we show that allometric patterns cannot be used to infer the underlying heterochronic processes. We present a case study of the water strider genus Limnoporus Stål (Heteroptera: Gerridae) to illuminate the distinct roles that allometry and heterochrony play in integrated studies of the evolution of form. Multivariate analyses reveal several evolutionary modifications of growth trajectories (changes in direction, lateral transposition, and ontogenetic scaling), which are fairly consistent with the hypothesized phylogeny of the genus. Because there is no positive correlation between instar durations and size increments, size cannot be used as a proxy for age data in studies of heterochrony. In fact, a measure of overall size itself shows a remarkable variety of heterochronic changes among the six species. Mixtures of several heterochronic processes predominate over the more unitary reflections of "pure" processes. Heterochronic changes in different branches of the phylogeny, apparently independent of size scaling, suggest considerable potential for adaptive evolution. "Local" differentiation of ontogenetic traits within small clades may be at least as important as "global" evolutionary trends in large clades and will often be missed in "global" analyses.
异时性和异速生长都涉及个体发育的进化修饰。虽然识别异时过程需要形态学和年龄数据，但研究异速生长不需要年龄数据。通过一个简单的图形模型，我们表明异速生长模式不能用于推断潜在的异时过程。我们以水黾属Limnoporus Stål（半翅目：黾蝽科）为例，以阐明异速生长和异时性在形态进化综合研究中所起的不同作用。多变量分析揭示了生长轨迹的几种进化修饰（方向变化、横向移位和个体发育缩放），这与该属的假设系统发育相当一致。由于龄期持续时间和大小增量之间没有正相关，在异时性研究中，大小不能用作年龄数据的替代指标。事实上，整体大小的度量本身在六个物种中显示出显著多样的异时变化。几种异时过程的混合比“纯粹”过程的更单一反映更为普遍。系统发育不同分支中的异时变化显然与大小缩放无关，这表明适应性进化具有相当大的潜力。小分支内个体发育特征的“局部”分化可能至少与大分支中的“全局”进化趋势一样重要，并且在“全局”分析中常常会被忽略。
