Trabecular bone architecture in the stylopod epiphyses of mustelids (Mammalia, Carnivora)

Abstract

Mustelidae, a carnivoran clade that includes for instance weasels, badgers, otters and martens, has undergone several evolutionary transitions of lifestyle, resulting in specializations for fossorial, natatorial and scansorial locomotion, in addition to more generalized species. The family is therefore regarded as offering an adequate framework for morpho-functional analyses. However, the architecture of the epiphyseal trabecular bone, which is argued to be particularly responsive to the biomechanical environment, has never been studied. Here, we quantify trabecular bone parameters of the proximal and distal epiphyses of the humerus and femur in 29 species of mustelids and assess the differences of these parameters among groups defined a priori based on the aforementioned locomotor types. The parameters are assessed in a phylogenetic framework, taking into account the potential effect on an individual's body mass. The range of variation described by the acquired parameters is relatively restricted when compared to that of other clades. Generalists, however, are featuring a wider range of variation than the other types. While clear discrimination of locomotor types is difficult, some differences were highlighted by our analysis, such as a greater bone fraction associated with the natatorial taxa, which we discuss in a functional context.

Differing effects of size and lifestyle on bone structure in mammals

“…Previous examinations of several levels of organisation of bone structure, be it histology [70,71], microanatomy (e.g. trabecular architecture [43,50,[72][73][74][75]), or gross morphology [22,23], documented various patterns of correlation with species' phylogenetic relationships, lifestyle, and body size. This work attempts to tease apart these effects with a comparative analysis relying on a sample encompassing multiple convergent acquisitions of the same lifestyle, covering as extensively as possible the body size range within each clade, and using subsets of data when lifestyles significantly differ in the represented species' body size.…”

First evidence of convergent lifestyle signal in reptile skull roof microanatomy

“…This transformed tree was then used for an rrpp regression with 10,000 permutations. If the recovered lambda was negative or greater than 1, its value was forced to be 0 or 1, respectively (see similar protocol in Amson and Kilbourne [ 167 ]). All p values were adjusted with the Holm method [ 168 ] using the p.adjust function of the built-in stats package.…”

Integrative Approach Uncovers New Patterns of Ecomorphological Convergence in Slow Arboreal Xenarthrans

“…However, some in vivo works have revealed that diaphyseal internal bone functional adaptation can be more complex than modeled (e.g., Lanyon and Rubin 1985;Judex et al 1997;Demes et al 1998;Wallace et al 2014). Recent analyses of how CSP and trabecular structure have evolved according to ecology using a phylogenetic framework have revealed complex/unexpected adaptative scenarios that can probably be explained by heterogeneous and disparate bone-dependent or trait-dependent models of morphological diversification (e.g., Amson and Kilbourne 2019;Scheidt et al 2019;Parsi-Pour and Kilbourne 2020). It is another element in support of the need to use model-fitting analysis in future studies, as suggested above.…”