Data from: On the relationship between ontogenetic and static allometry

Ontogenetic and static allometries describe how a character changes in size when the size of the organism changes during ontogeny and among individuals measured at the same developmental stage, respectively. Understanding the relationship between these two types of allometry is crucial to understanding the evolution of allometry and, more generally, the evolution of shape. However, the effects of ontogenetic allometry on static allometry remain largely unexplored. Here, we first show analytically how individual variation in ontogenetic allometry and body size affect static allometry. Using two longitudinal data sets on ontogenetic and static allometry, we then estimate variances and covariances for the different parameters of the ontogenetic allometry defined in our model and assess their relative contribution to the static allometric slope. The mean ontogenetic allometry is the main parameter that determines the static allometric slope, while the covariance between the ontogenetic allometric slope and body size generates most of the discrepancies between ontogenetic and static allometry. These results suggest that the apparent evolutionary stasis of the static allometric slope is not generated by internal (developmental) constraints but more likely results from external constraints imposed by selection.

个体发育异速生长（ontogenetic allometry）与静态异速生长（static allometry）分别描述了两类尺寸变化规律：前者刻画生物体在个体发育过程中，整体尺寸改变时某一性状的大小变化情况；后者则反映同一发育阶段下的不同被测个体间，性状尺寸随生物体整体尺寸的变化规律。明晰这两类异速生长之间的关联，对于理解异速生长的演化，乃至更广泛意义上的形态演化均至关重要。然而，个体发育异速生长对静态异速生长的影响，目前仍未得到充分探索。本研究首先通过解析方法，阐明了个体发育异速生长的个体差异与生物体尺寸如何对静态异速生长产生影响。我们利用两套包含个体发育异速生长与静态异速生长的纵向数据集，对研究模型中定义的个体发育异速生长各参数的方差与协方差进行估算，并评估它们对静态异速生长斜率的相对贡献度。结果表明，平均个体发育异速生长是决定静态异速生长斜率的核心参数；而个体发育异速生长斜率与生物体尺寸之间的协方差，则是造成个体发育异速生长与静态异速生长之间出现多数偏差的主要来源。这些结果提示，静态异速生长斜率所呈现的演化停滞现象，并非由内部（发育）约束所导致，而更可能源于自然选择施加的外部约束。