Morphometric variation at different spatial scales: coordination and compensation in the emergence of organismal form

It is a classic aim of quantitative and evolutionary biology to infer genetic architecture and potential evolutionary responses to selection from the variance-covariance structure of measured traits. But a meaningful genetic or developmental interpretation of raw covariances is difficult, and classic concepts of morphological integration do not directly apply to modern morphometric data. Here we present a new morphometric strategy based on the comparison of morphological variation across different spatial scales. If anatomical elements vary completely independently, then their variance accumulates at larger scales or for structures composed of multiple elements: morphological variance would be a power function of spatial scale. Deviations from this pattern of `variational self-similarity'' (serving as a null-model of completely uncoordinated growth) indicate genetic or developmental co-regulation of anatomical components. We present biometric strategies and R scripts for identifying pat...