Understanding the causes of body shape variability across the tree of life is one of the central issues surrounding the origins of biodiversity. One potential mechanism driving observed patterns of shape disparity is a strongly conserved relationship between size and shape. Conserved allometry has been shown to account for as much as 80% of shape variation in some vertebrate groups. Here, we quantify the amount of body shape disparity attributable to changes in body size across nearly 800 species of Indo-Pacific shore fishes using a phylogenetic framework to analyze 17 geometric landmarks positioned to capture general body shape and functionally-significant features. In marked contrast to other vertebrate lineages, we find that changes in body size only explain 2.9% of the body shape variation across fishes, ranging from 3-50% within our 11 sampled families. We also find a slight but significant trend of decreasing rates of shape evolution with increasing size. Our results suggest that the influence of size on fish shape has largely been overwhelmed by lineage-specific patterns of diversification that have produced the modern landscape of highly diverse forms that we currently observe in nature.

Landmark DataCSV file with landmark data for all species present in the phylogeny. This is a subset of previously unpublished data that were used in Claverie T, Wainwright PC (2014) A Morphospace for Reef Fishes: Elongation Is the Dominant Axis of Body Shape Evolution. PLoS ONE 9(11): e112732. https://doi.org/10.1371/journal.pone.0112732 Data provided courtesy of the authors.trimmed_tps_Claverie2014.csvTime Tree FileTime tree file trimmed to species with TPS data. Original tree published by Rabosky et al. (2013). If you use these data, please also credit the original source: Rabosky DL, Santini F, Eastman J, Smtih SA, Sidlauskas B, Chang J, Alfaro ME (2013) Rates of speciation and morphological evolution are correlated across the largest vertebrate radiation. Nature Communications 4: 1958. https://doi.org/10.1038/ncomms2958 and Rabosky DL, Santini F, Eastman J, Smtih SA, Sidlauskas B, Chang J, Alfaro ME (2013) Data from: Rates of speciation and morphological evolution are correlated across the largest vertebrate radiation. Dryad Digital Repository. https://doi.org/10.5061/dryad.j4802 trimmed_Rabosky2013.tre