Eloy Gálvez-López

The diversity of brain size and organization across mammals reflects how evolutionary and ecological pressures have shaped neural architecture through time. Yet, how these selective pressures translated into measurable variation in the proportions and overall shape of the brain across species remains poorly understood. In this study, we used high‐resolution virtual endocasts from 41 musteloid species (e.g., otters, skunks, raccoons) to quantify variation in endocranial composition and shape. We analyzed both the complete endocast and its principal subdivisions (olfactory bulbs (OB), cerebrum, and hindbrain) using a combination of compositional data analysis and 3D geometric morphometrics. Phylogenetically informed regressions (PGLS) and model comparisons were used to assess the effects of endocranial size, locomotion, diet, and taxonomy on both the regional proportions and the overall shape of the endocranial cast. Musteloid brain organization is mostly driven by size‐dependent scaling: larger brains have enlarged cerebra, reduced olfactory and hindbrain regions, and rounder endocasts. However, some lineages markedly deviate from this largely conserved allometry: otters (Lutrinae) exhibit proportionally enlarged cerebra and strongly reduced OB, whereas skunks (Mephitidae) show the reverse pattern, emphasizing enhanced olfactory investment. Feeding ecology also contributes to variation in brain organization, as piscivores show disproportionately smaller OB compared with other feeding guilds. In contrast, locomotor mode has little explanatory power for either endocranial composition or shape. Brain evolution in musteloids is therefore not uniform: a common scaling pattern dominates, but lineage‐ and diet‐specific adjustments modify how brain regions are proportioned.

The veiled chameleon, Chamaeleo calyptratus, is a model organism in the study of reptile development. The extreme size of its cranial casque relative to other chameleons has been linked to high bite forces and conspecific signaling, yet its unique head anatomy has not been described. In general, detailed accounts of chameleon cranial musculature are scarce and not in formats that are easily accessible for use by researchers and educators. In this study, we provide the first complete description of both the cranial osteology and soft tissues in two adult specimens, exploring differences between sexes. Utilizing contrast‐enhancing staining techniques, microCT scanning and deep learning models for segmentation, we have generated the first digital anatomical atlases of the chameleon skull, nervous system, cranial muscles and, in the female, hyolingual muscles. This includes the first maps of chameleon cranial sutures and muscle attachment sites. Our results show that the sexes differ most in the structure of the facial skeleton and the enlarged cranial casque. Many osteological differences are reflected in muscle topology and size, where the male presents a considerably larger jaw adductor. These atlases represent novel insights and potential applications for future research and education in reptile evolution and development. As an example, we have published a series of lesson plans alongside our atlases to help educators bridge the gap between theoretical knowledge and hands‐on analysis in comparative anatomy.

The mechanical properties of dietary items are known to influence skull morphology, either through evolution or by phenotypic plasticity. Here, we investigated the impact of supplementary feeding of peanuts on the morphology of red squirrels (Sciurus vulgaris) from five populations in Britain (North Scotland, Borders, Jersey and two temporally distinct populations from Formby (Merseyside)). Stable isotope analysis confirmed dietary ecology in 58 specimens. Geometric morphometrics were used to analyse three-dimensional and two-dimensional shape variation across 113 crania and 388 mandibles, respectively. Nitrogen isotope ratios (δ15N) were lower in the 1990s and 2010s Formby squirrels (suggesting a diet with an increased proportion of peanuts), and higher in other populations. Significant differences in cranio-mandibular shape were found between all populations, with 1990s Formby red squirrels exhibiting a morphology associated with reduced masticatory efficiency. This effect was partially reversed following a reduction in supplementary feeding of peanuts. We propose that these morphological changes are related to the reduced mechanical effort needed to process peanuts relative to naturally occurring food items. This could be an example of diet-induced plastic changes to the skeleton in non-muroid wild mammals, although further research is needed to exclude other driving factors such as genetics.

The increase in student mobility world-wide and the globalization of teaching and learning practices has resulted in the prevalence of multicultural classrooms. However, knowledge on how cultural differences interact with increasingly student-centered practices is scarce. This is especially relevant for the provision of effective formative feedback, which as any form of dialogue, is bound to be affected by cultural customs and expectations. This rigorous literature review aims to examine the current knowledge on the role of culture in the provision of formative feedback in higher education: cultural differences, potential conflicts, and mitigation strategies. The results highlight three main themes of variation: perception of formative feedback, feedback as communication, and the affective/interpersonal domain. Three strategies to address potential clashes derived from these cultural differences are provided, and their applicability discussed. Finally, some issues and concerns are raised about current practices on studying cultural differences in the provision of formative feedback.

The effect of size, phylogeny, and locomotor habit, on shape was tested in 213 scapulas from 101 carnivoran species using 3D geometric morphometric methods. The sampled species spanned the whole size range and locomotor patterns in Carnivora. The results of the present study indicate that, in this order, scapula shape responds to the complex interaction of allometric, phylogenetic, and functional effects. Furthermore, evidence for differential scaling in the shape of the carnivoran scapula was found, which might be related to scaling differences among carnivoran families. Additionally, most allometric shape variation in the carnivoran scapula was related to size changes along phyletic lines. Locomotor-related shape differences were assessed using canonical variate analysis. Most locomotor habits could be significantly separated from each other based on scapula shape, although high misclassification rates were obtained when comparing semiarboreal and semifossorial carnivorans to other locomotor types. Locomotor indicators in the scapula shape of extant carnivorans seemed independent of size or shared ancestry and could be related to muscular function. These locomotor indicators were then used to infer the locomotor habits of several internal nodes of the carnivoran phylogeny, whose scapular size and shape was reconstructed using weighted square-change parsimony. According to scapula size and shape, the carnivoran ancestor was a medium-sized scansorial animal (i.e., it spent most of its time on the ground, but was a good climber).

The scaling pattern of the hind limb in Carnivora was determined using a sample of 13 variables measured on the femur, tibia, and calcaneus, of 429 specimens belonging to 141 species. Standardized major axis regressions on body mass were calculated for all variables, using both traditional regression methods and phylogenetically independent contrasts (PIC). Significant differences were found between the allometric slopes obtained with traditional and PIC regression methods, emphasizing the need to take into account phylogenetic relatedness in scaling studies. Overall, the scaling of the carnivoran hind limb conformed to geometric similarity, although some deviations from its predictions (including differential scaling) were detected, especially in relation with swimming adaptations. The scaling pattern of several phyletic lines and locomotor habits within Carnivora was also determined. Significant deviations from the scaling pattern of the order were found in some phyletic lines, but not in the locomotor habit subsamples. This suggests that the scaling of the carnivoran hind limb is both more heavily influenced by phylogenetic relatedness than by locomotor specializations, and more conservative than that of the forelimb. Finally, together with our previous work on the carnivoran forelimb, the results of the present study suggest that, in large non-aquatic carnivorans, size-related increases in bone stresses are compensated primarily by limb posture changes instead of by modifying limb bone scaling. However, increasing bone robusticity might also occur in the forelimb in response to the heavier stresses acting on the forelimbs due to asymmetrical body weight distribution.

The scaling pattern of the forelimb in Carnivora was determined using a sample of 30 variables measured on the scapula, humerus, radius, ulna, and third metacarpal, of 429 specimens belonging to 137 species of Carnivora. Standardized major axis regressions on body mass were calculated for all variables, using both traditional regression methods and phylogenetically independent contrasts (PIC). In agreement with previous studies on the scaling of the appendicular skeleton, conformity to either the geometric similarity hypothesis or the elastic similarity hypothesis was low. The scaling pattern of several phyletic lines and locomotor types within Carnivora was also determined, and significant deviations from the scaling pattern of the order were found in some of these subsamples. Furthermore, significant evidence for differential scaling was found for several variables, both in the whole sample and in various phylogenetic and locomotor subsamples. Contrary to previous studies, significant differences were found between the allometric exponents obtained with traditional and PIC regression methods, emphasizing the need to take into account phylogenetic relatedness in scaling studies. In light of these and previous results, we conclude that similarity hypotheses are too simplistic to describe scaling patterns in the carnivoran appendicular skeleton, and thus we propose that scaling hypotheses should be built from similarities in the scaling patterns of phylogenetically narrow samples of species with similar locomotor requirements. The present work is a first step in the study of those samples.

European and American minks are very similar in ecology, behavior and morphology. Both species hunt terrestrial vertebrates and aquatic prey, but the American mink is a more generalist predator which, among other factors, allows it to outcompete the European mink in areas where it has been introduced. We used 3D geometric morphometrics and estimates of muscle mechanical advantage to assess the degree of variation in mandibular morphology, and to determine whether such variation reflects dietary differences between the two species. The three main axes of variation represented interspecific differences, a common allometric trajectory between species and sexes, and the interspecific effect of sexual size dimorphism, with males having overall stronger bites than females. Differences in mandible shape and biomechanical parameters suggest that American minks are better equipped for preying on terrestrial vertebrates, while the features seen in European mink could be related to tougher prey, fish capture, or both. Additionally, within each species, the larger specimens of each sex present indicators of a higher percentage of terrestrial prey in their diet. These results indicate a low potential dietary overlap between both species, suggesting that factors other than prey competition may have a role in the decline of the European mink.

European and American minks (Mustela lutreola and Neovison vison, respectively) are very similar in their ecology, behavior, and morphology. However, the American mink is a generalist predator and seems to adapt better to anthropized environments, allowing it to outcompete the European mink in areas where it has been introduced, threatening the survival of the native species. To assess whether morphological differences may be contributing to the success of the American mink relative to the European mink, we analyzed shape variation in the cranium of both species using 3D geometric morphometrics. A set of 38 landmarks and 107 semilandmarks was used to study shape variation between and within species, and to assess how differences in size factored into that variation. Sexual dimorphism in both size and shape was also studied. Significant differences between species were found in cranial shape, but not in size. Relative to American mink, European mink have a shorter facial region with a rounder forehead and wider orbits, a longer neurocranium with less developed crests and processes, and an antero‐medially placed tympanic bullae with an anteriorly expanded cranial border. Within species, size‐related sexual dimorphism is highly significant, but sexual dimorphism in shape is only significant in American mink, not in European mink. Additionally, two trends common to both species were discovered, one related to allometric changes and another to sexual size dimorphism. Shape changes related to increasing size can be subdivided into two, probably related, groups: increased muscle force and growth. The first group somewhat parallels the differences between both mink species, while the second group of traits includes an anterodorsal expansion of the face, and the neurocranium shifting from a globous shape in small individuals to a dorsoventrally flattened ellipse in the largest ones. Finally, the sexual dimorphism trend, while also accounting for differences in muscle force, seems to be related to the observed dietary differences between males and females. Overall, differences between species and sexes, and shape changes with increasing size, seem to mainly relate to differences in masticatory‐muscle volume and therefore muscle force and bite force, which, in turn, relate to a wider range of potential prey (bigger prey, tougher shells). Thus, muscle force (and dietary range) would be larger in American mink than in European mink, in males than in females, and in larger individuals than in smaller ones.

Here, I study whether locomotor adaptations can be detected in limb bones using a univariate approach, and whether those results are affected by size and/or shared evolutionary history. Ultimately, it tests whether classical papers on locomotor adaptations should be trusted. To do that, I analyzed the effect of several factors (size, taxonomic group, and locomotor habit) on limb bone morphology using a set of 43 measurements of the scapula, long bones, and calcaneus, of 435 specimens belonging to 143 carnivoran species. Size was the main factor affecting limb morphology. Size‐corrected analyses revealed artifactual differences between various locomotion‐related categories in the analyses of raw data. Additionally, several between‐group differences were new to the size‐corrected analyses, suggesting that they were masked by the size‐effect. Phylogeny had also an important effect, although it only became apparent after removing the effect of size, probably due to the strong covariation of both factors. Regarding locomotor adaptations, locomotor type was used to represent locomotor specialization, and utilized habitat as an indicator of the capacity to adopt different modes of locomotion (running, swimming, climbing, and digging) and thus maximize resource exploitation by being capable of navigating all the substrates in the habitat they use. Locomotor type produced better results than utilized habitat, suggesting that carnivorans use locomotor specialization to minimize locomotion costs. The characteristic limb bone morphology for each locomotor type studied is described, including several adaptations and trends that are novel to the present study. Finally, the results presented here support the hypothesis of a “viverrid‐like”, forest‐dwelling carnivoran ancestor, either arboreal or terrestrial.