Data from: Quantifying shape and ecology in avian pedal claws: the relationship between the bony core and keratinous sheath
Hedrick, Brandon, Louisiana State University Health Sciences Center New Orleans
Cordero, Samantha, University of Pennsylvania
Zanno, Lindsay, North Carolina State University
Noto, Christopher, University of Wisconsin–Parkside
Dodson, Peter, University of Pennsylvania
Published Oct 01, 2019 on Dryad.
Cite this dataset
Hedrick, Brandon et al. (2019). Data from: Quantifying shape and ecology in avian pedal claws: the relationship between the bony core and keratinous sheath [Dataset]. Dryad. https://doi.org/10.5061/dryad.k492m37
Terrestrial tetrapods use their claws to interact with their environments in a plethora of ways. Birds in particular have developed a diversity of claw shapes since they are often not bound to terrestrial locomotion and have heterogeneous body masses ranging several orders of magnitude. Numerous previous studies have hypothesized a connection between pedal claw shape and ecological mode in birds, yet have generated conflicting results, spanning from clear ecological groupings based on claw shape to a complete overlap of ecological modes. The majority of these studies have relied on traditional morphometric arc measurements of keratinous sheaths and have variably accounted for likely confounding factors such as body mass and phylogenetic relatedness. To better address the hypothesized relationship between ecology and claw shape in birds, we collected 580 radiographs allowing visualization of the bony core and keratinous sheath shape in 21 avian orders. Geometric morphometrics was used to quantify bony core and keratinous sheath shape and was compared to results using traditional arc measurements. Neither approach significantly separates bird claws into coarse ecological categories after integrating body size and phylogenetic relatedness; however, some separation between ecological groups is evident and we find a gradual shift from the claw shape of ground-dwelling birds to those of predatory birds. Further, the bony claw core and keratinous sheath are significantly correlated, and the degree of functional integration does not differ across ecological groups. Therefore, it is likely possible to compare fossil bony cores with extant keratinous sheaths after applying corrections. Finally, traditional metrics and geometric morphometric shape are significantly, yet loosely correlated. Based on these results, future workers are encouraged to use geometric morphometric approaches to study claw geometry and account for confounding factors such as body size, phylogeny, and individual variation prior to predicting ecology in fossil taxa.
Supplemental Tables 1-4
Supplemental Table 1: Statistical results for traditional morphometric analyses. Mean, standard deviation, and confidence intervals for intraspecific analyses. PGLS of log-transformed keratinous sheath arc and log-transformed bony core arc. Phylogenetic ANOVAs for traditional morphometrics. T-test comparing bony core and keratinous sheath log-transformed arc measurements.
Supplemental Table 2: Specimen number, species name, family, traditional morphometric metrics, and the first 10 PC scores for geometric morphometric data for all 580 individuals.
Supplemental Table 3: Statistical results for geometric morphometric analyses. Tests for allometry and phylogenetic signal. Claw shape by group including centroid size as a covariate and pairwise comparisons among ecological groups. Disparity, functional integration, and modularity analyses.
Supplemental Table 4: Specimen number, species name, family, centroid size mean, traditional morphometric metrics, and the first 10 PC scores for geometric morphometric data for species means (n = 145).
Figure S1. Tree based on Jetz et al. (2012) showing the phylogenetic relationships between the 145 taxa used in the study. Tips are colored by locomotor mode, showing numerous convergences in mode across taxa studied. Blue = predatory, red = flying, yellow = ground.
Figure S2. Individual level two-block partial least squares analysis of the bony core landmark configuration and the keratinous sheath landmark configuration using geometric morphometrics. TPS grids show differences in shape along each shape block. Blue = predatory, red = flying, yellow = ground.
580 radiographs of bird claws. See supplemental tables (Table S2) for additional information.