Ecological associations of autopodial osteology in Neotropical geckos

Abstract

Coevolution of form and function inspires investigation of associations between morphological variation and the exploitation of specific ecological settings. Such relationships, based mostly on traits of external morphology, have been extensively described for vertebrates, and especially so for squamates. External features are, however, composed by both soft tissues and bones, and these likely play different biomechanical roles during locomotion, such as in the autopodia. Therefore, ecological trends identified on the basis of external morphological measurements may not be directly correlated with equivalent variation in osteology. Here, we investigate how refined parameters of autopodial osteology relate to ecology, by contrasting climbing and nonclimbing geckos. Our first step consisted of inferring how external and osteological morphometric traits coevolved in the group. Our results corroborate the hypothesis of coevolution between external and osteological elements in the autopodia of geckos, and provides evidence for associations between specific osteological traits and preferred locomotor habit. Specifically, nonclimbers exhibit longer ultimate and penultimate phalanges of Digit V in the manus and pes and also a longer fifth metatarsal in comparison with climbers, a pattern discussed here in the context of the differential demands made upon locomotion in specific ecological contexts. Our study highlights the relevance of osteological information for discussing the evolution of ecological associations of the tetrapod autopodium. J. Morphol. 278:290-299, 2017. © 2017 Wiley Periodicals, Inc.

Evolution of pedal digit orientation and morphology in relation to acquisition and secondary loss of the adhesive system in geckos

“…The results of other studies of gecko lineages are somewhat consistent with our findings. Differences between climbers and non‐climbers were not able to be clearly delineated by Johnson et al () in the Pachydactylus radiation, but among neotropical geckos, climbing geckos have shorter digits and a shorter fifth metatarsal when compared to nonclimbing lineages (Rothier, Brandt, & Kohlsdorf, ). These latter results are compatible with our findings and suggest that this pattern is repeated across the gekkotan phylogeny.…”

Development and function explain the modular evolution of phalanges in gecko lizards

“…We measured three digits exhibiting the same phalangeal formula across all sampled species (digit III = 4, digit IV = 5, digit V = 3). We measured digit V in 13 gecko species for a previous publication [16], and new measurements for digits III and IV were acquired from the same X-ray images used before. Digit I was not measured because its developmental identity differs from that of the remaining digits [30]; digit II was also excluded because it was damaged in several specimens and inclusion would have restricted sample royalsocietypublishing.org/journal/rspb Proc.…”

“…Although scarce, exceptions for such a constrained pattern of variation have been detected in extant lineages, including Squamata (lizards and snakes). Lizards emerge as an excellent model system to evaluate modularity in the autopodium also owing to the ecological diversity and the remarkable variation in limb morphology reported in several clades [16][17][18][19][20].…”

“…Geckos are renowned for the presence of sub-digital adhesive toepads, which have independently evolved several times in the lineage, often associated with remarkable climbing abilities [17,21,22]. In these lizards, pad evolution seems associated with several anatomical modifications in the autopodium, including specific shape and size patterns of the phalanges [16,17,23,24]. Biomechanical specialization during locomotion in padded geckos also involves distoproximal hyperextension of the digits [23,25].…”

Skin hydrophobicity as an adaptation for self‐cleaning in geckos

“…The study of evolutionary morphology tackles questions examining how morphological traits may have evolved (Richter & Wirkner, 2014). Common study designs include mapping traits onto a phylogeny (Finarelli & Flynn, 2006; Hwang & Weirauch, 2012; King & Lee, 2015) or identifying correlations between traits and ecological factors (Kohlsdorf, Garland Jr, & Navas, 2001; Mihalitsis & Bellwood, 2019; Riedel, Vucko, Blomberg, Robson, & Schwarzkopf, 2019; Rothier, Brandt, & Kohlsdorf, 2017). Although these studies provide useful insights into the complex evolution of organisms and potential processes of adaptation, they only constitute the starting point of evolutionary research.…”