A Morphological Method to Approximate Jumping Performance in Anurans for Macroevolutionary Studies

Abstract

Organismal performance is often key in understanding macroevolutionary patterns but characterizing performance across many species is challenging, as the disparate geographic locations of taxa often prohibit in vivo measures. In theory, however, inferences on the evolution of performance could be investigated using anatomical approximations of performance parameters, allowing for a wider range of species to be sampled. In this study, we use biological and physical principles to mathematically derive three size-standardized anatomical approximations for three different aspects of jumping performance at take-off in anurans: peak jumping velocity, energy, and power. We also describe several ways to parameterize these approximations using, for example, measurements of leg length, leg muscle mass, and body mass. We evaluate the efficacy of these approaches via comparison with direct size-standardized measures of jumping performance across 256 individuals from 51 anuran species. Using both phylogenetic and non-phylogenetic approaches, we find that two of the three anatomical approximations (velocity and energy) are highly correlated with in vivo measures, while a third (power) is not. This reveals that the former may serve as reliable estimates of those aspects of jumping performance, while the latter approximation does not capture all aspects of jumping power in anurans. We also report significant phylogenetic signal for the approximations, as found in in vivo measures. These analyses demonstrate the utility of anatomical approximations for use in macroevolutionary studies. Relative to in vivo laboratory methods, this new method allows for broad museum-based taxonomic surveys of jumping performance in anurans and possibly other jumping animals.Motivated by their example, we develop three size-standardized anatomical approximations for jumping performance to serve as estimates of three key aspects of jumping performance at take-off in anurans: peak velocity, energy, and power. Since these three performance measures commonly scale with body size (see e.g., Marsh and John-Alder 1994;Astley 2016), we account for this pattern by size-standardizing the approximations. Specifically, our concern is whether these may serve as reasonable approximations of the relative differences in jumping performance between species, and thus may serve as approximate measures of performance in macroevolutionary studies. Thus, we evaluate the efficacy of the sizestandardized approximations by comparing them with direct size-standardized measures of performance using a dataset containing 256 individuals and 51 species of anurans that span a broad range of morphological, ecological, and geographic diversity. We also describe several ways to parameterize these anatomical approximations to obtain precise estimates of jumping performance. In developing these approximations, we provide a new avenue for obtaining estimates of jumping performance, and we set the stage for future broad-scale macroevolutionary studies of jumping performance in anurans a...

Evolutionary allometry of sexual dimorphism of jumping performance in anurans

“…Anatomical approximations of peak jumping performance (velocity and energy) at take-off were obtained using Eqs. 1 and 3 of Juarez et al (2020), based upon a series of anatomical measurements, as per below. To obtain these estimates, we measured body mass, snout-vent length, muscle volume, and limb length (L com ) from each individual.…”

“…To obtain these estimates, we measured body mass, snout-vent length, muscle volume, and limb length (L com ) from each individual. Briefly, L com , the distance from the toes to the center of mass, was found as the summation of the sacral length and hindlimb length (Peplowski and Marsh 1997;Juarez et al 2020), and limb muscle volume was obtained as the bilateral sum of the muscle volume of the fore and hind limbs:…”

“…, where r 1 and r 2 are the radii represented by half the muscle depth and width of the thigh, r 3 and r 4 are half the muscle depth and width of the calf, and H 1 and H 2 are cone heights represented by half the femur and tibiofibula lengths, respectively (for additional details see Appendix). From these measures, approximations of jumping velocity and jumping energy were then obtained (see Juarez et al 2020). Specifically, the anatomical approximation for peak jump- .…”

“…Furthermore, fecundity selection has been linked to the evolution of sexual size dimorphism in some species (Han and Fu 2013) and this may be important in the evolution of interspecific allometry. Furthermore, the biomechanics of jumping performance is well-studied in this group, including recent advancements that allow the approximation of jumping performance from anatomical information (Juarez et al 2020).…”

“…Since several of these traits covary strongly with body size (Moen 2019;Juarez et al 2020), interpretations of sex-specific patterns are compromised. Thus, as is common in the field (e.g., Astley 2016), we size-standardized L com using snout-vent length, and muscle vol- ume and jumping energy using body mass; the resulting relative muscle volume, relative L com , and mass-specific jumping energy were used in subsequent analyses.…”