DOI: 10.5061/dryad.7vf4004
title: Data from: Morphological diversification of biomechanical traits: mustelid locomotor specializations and the macroevolution of long bone cross-sectional morphology

description: Morphological diversity of limb bone lengths, diameters, and proportions
 in mammals is known to vary strongly with locomotor habit. It remains less
 well known how different locomotor habits are correlated with
 cross-sectional traits of the limb skeleton, such as cross-sectional area
 (CSA), second moments of area (SMA), and section modulus (MOD) and whether
 these traits have evolved adaptively. CSA and SMA represent the bone’s
 resistance to axial compression and bending, respectively, whereas MOD
 represents bone structural strength related to shape. Sampling 28 species
 of mustelids, a carnivoran lineage with diverse locomotor habits, we
 tested for differences in humeral, radial, and ulnar cross-sectional
 traits among specialists for climbing, digging, and swimming, in addition
 to generalists. Given that the limbs of digging specialists function in
 the dense substance of soil, and that swimming specialists need to
 counteract buoyancy, we predicted that these mustelids with these
 specializations should have the greatest values of cross-sectional traits.
 We analyzed cross-sectional traits (calculated via µCT scanning and
 rendered dimensionless) in 5% increments along a bone’s length and found
 significant differences in among locomotor habits, though the differences
 in ulnar cross-sectional traits were fewer than those for the humerus and
 radius. Swimming specialists had the greatest values of cross-sectional
 traits, followed by digging specialists. Climbing specialists had the
 lowest values of cross-sectional traits. However, phylogenetic affinity
 underlies these results. Fitting models of trait evolution to CSA and SMA
 revealed that a multi-rate Brownian motion model and a multi-optima
 Ornstein-Uhlenbeck model are the best-fitting models of evolution for
 these traits. However, inspection of α-values uncovered that many of the
 OU models did not differ from a Brownian motion model. Within Mustelidae,
 differences in limb function and locomotor habit influence cross-sectional
 traits in ways that produce patterns that may diverge from adaptive
 patterns exhibited by external traits (e.g., bone lengths) of the
 mammalian limb skeleton. These results suggest that not all the traits of
 a single organ evolve under a single evolutionary process and that models
 of trait evolution should be fit to a range of traits for a better
 understanding of the evolution of the mammalian locomotor system.
description: Humerus
 LengthsHumeral lengths used to
 render humeral cross-sectional traits dimensionless.Radius
 LengthsRadial lengths used to
 render radial cross-sectional traits dimensionless.Ulna
 LengthsUlnar lengths used to
 render ulnar cross-sectional traits dimensionless.Mustelid
 GroupingsLocomotor habit of each
 mustelid species. For source of assigned habit, see Table 1 of
 article.Humeral Cross-Sectional
 Data All IndividualsRaw humeral
 cross-sectional trait data for all individuals. Cross-sectional area
 (CSA), second moment of area (SMA), and section modulus (MOD) respectively
 have units of mm^2, mm^4, and mm^3. Column names denote increment of bone
 length (i.e., P5 indicates 5% of bone length, P10 indicates 10% of bone
 length, etc.).Dimensionless Humeral
 Cross-Sectional Data Species MeansSpecies means for
 humeral cross-sectional traits. Values were rendered dimensionless using
 humeral lengths (see article). Column names denote increment of bone
 length (i.e., P5 indicates 5% of bone length, P10 indicates 10% of bone
 length, etc.).Radial Cross-Sectional
 Data All IndividualsRaw radial
 cross-sectional trait data for all individuals. Cross-sectional area
 (CSA), second moment of area (SMA), and section modulus (MOD) respectively
 have units of mm^2, mm^4, and mm^3. Column names denote increment of bone
 length (i.e., P5 indicates 5% of bone length, P10 indicates 10% of bone
 length, etc.).Dimensionless Radial
 Cross-Sectional Data Species MeansSpecies means for radial
 cross-sectional traits. Values were rendered dimensionless using ulna
 lengths (see article). Column names denote increment of bone length (i.e.,
 P5 indicates 5% of bone length, P10 indicates 10% of bone length,
 etc.).Ulnar Cross-Sectional
 Data All IndividualsRaw ulnar
 cross-sectional trait data for all individuals. Cross-sectional area
 (CSA), second moment of area (SMA), and section modulus (MOD) respectively
 have units of mm^2, mm^4, and mm^3. Column names denote increment of bone
 length (i.e., P5 indicates 5% of bone length, P10 indicates 10% of bone
 length, etc.).Dimensionless Ulnar
 Cross-Sectional Data Species MeansSpecies means for ulnar
 cross-sectional traits. Values were rendered dimensionless using ulna
 lengths (see article). Column names denote increment of bone length (i.e.,
 P5 indicates 5% of bone length, P10 indicates 10% of bone length,
 etc.).Phylogeny of Sampled
 Mustelidae.Phylogeny trimmed from
 Law, C.J., Slater, G.J., & Mehta, R.S. 2018. Lineage diversity and
 size disparity in Musteloidea: testing patterns of adaptive radiation
 using molecular and fossil-based methods. Syst. Biol. 67:
 127-144.Mustelidae
 N_28R Code for Analysis of
 Cross-Sectional TraitsR code to run the
 analyses of our study, from rendering the original data dimensionless to
 fitting models of trait evolution and testing for allometry. The code uses
 humeral CSA as an example (this can of course be changed to other traits),
 being annotated for clarity.Cross-Section
 Code.zipImage Stacks BoneJ
 AnalysisTIFF (originally DICOM)
 image stacks analyzed with BoneJ for each sampled individual. Notes on
 institutional abbreviation, orientation of the cranio-caudal axis, and
 image stacks as increments of bone length included as a PDF
 document.BoneJ
 MeasurementsOutput from image stacks
 analyzed with BoneJ for each sampled individual. Notes on institutional
 abbreviation, orientation of the cranio-caudal axis, and image stacks as
 increments of bone length included as a PDF document.