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ABSTRACT Aim Location Methods Results Main Conclusions Global warming has highlighted the importance of understanding the role of thermal tolerance as a driver of species distributions, especially for ectotherms. Here we analyse interactions between latitude, elevation and arboreality as predictors of geographic patterns of thermal tolerance in ants.The collected data are distributed globally.We first tested the effect of latitude, elevation and its interactive effect on ant CTmax and CTmin. Second, we tested whether CTmax and CTmin are phylogenetic clustering. Finally, we tested whether CTmax and CTmin can be explained by nesting microhabitat (ground vs. tree‐nesting species) and whether the probability of occurrence of tree‐nesting species along thermal gradients helps explain the global pattern in ant CTmax.CTmax and CTmin displayed high and low phylogenetic signals respectively and therefore showed different responses to geographic gradients. Notably, we found that CTmax was higher in higher latitudes. This was explained by a lack of elevational turnover at high latitudes among tree‐nesting species, which are exposed to warmer microclimates and have higher CTmax compared with ground‐nesting species. CTmin decreased with elevation at low latitudes, but did not vary with elevation at higher latitudes.Our findings highlight the important influence of arboreality on the macroecology of thermal tolerance, substantially modifying traditional notions of variation along latitudinal and elevation gradients. [ABSTRACT FROM AUTHOR]

Because of the brief and cryptic nature of predatory behavior, sentinel prey has been widely adopted as an indirect way to identify predators and understand trophic interactions. However, sentinel prey presents only static visual cues, potentially biasing toward visually oriented predators while ignoring those that utilize other sensory cues for foraging. Despite this, the effectiveness of sentinel prey has rarely been tested. In this study, we focused on the weaver ant Oecophylla smaragdina Fabricius (Hymenoptera: Formicidae), a keystone predator widespread in the Asian and Australian tropics. As this species has large eyes and is known to visually navigate in its arboreal habitats, we hypothesized that it relies on visual cues to forage and that its predatory behavior will be captured by caterpillar‐shaped sentinel prey. Ants were collected as colonies, and preference trials on baits were conducted using combinations of olfactory and static visual cues, including the caterpillar shape. Surprisingly, O. smaragdina showed little or no preference for baits in the absence of olfactory cues and did not differentiate the shapes of baits regardless of olfactory cues. Our results indicate that O. smaragdina is likely to make predatory decisions based primarily on olfactory cues, whereas visual cues might be used for other behaviors. Furthermore, O. smaragdina is likely to be left out by the predation studies using sentinel prey models, which is particularly alarming considering the dominant role of this species in the trophic interactions of tropical rainforests. Our study demonstrates that morphological characteristics, arboreal habitats, and visually oriented behavior do not necessarily suggest the use of static visual cues for predatory decisions. We suggest that sentinel prey models should not be used alone when the dominant predators are unlikely to use visual cues to make predatory decisions. [ABSTRACT FROM AUTHOR]

Objectives: Calcaneal external shape differs among nonhuman primates relative to locomotion. Such relationships between whole‐bone calcaneal trabecular structure and locomotion, however, have yet to be studied. Here we analyze calcaneal trabecular architecture in Gorilla gorilla gorilla, Gorilla beringei beringei, and G. b. graueri to investigate general trends and fine‐grained differences among gorilla taxa relative to locomotion. Materials and methods: Calcanei were micro‐CT scanned. A three‐dimensional geometric morphometric sliding semilandmark analysis was carried out and the final landmark configurations used to position 156 volumes of interest. Trabecular thickness (Tb.Th), trabecular spacing (Tb.Sp), and bone volume fraction (BV/TV) were calculated using the BoneJ plugin for ImageJ and MATLAB. Non‐parametric MANOVAs were run to test for significant differences among taxa in parameter raw values and z‐scores. Parameter distributions were visualized using color maps and summarized using principal components analysis. Results: There are no significant differences in raw BV/TV or Tb.Th among gorillas, however G. b. beringei significantly differs in z‐scores for both parameters (p = <0.0271). All three taxa exhibit relatively lower BV/TV and Tb.Th in the posterior half of the calcaneus. This gradation is exacerbated in G. b. beringei. G. b. graueri significantly differs from other taxa in Tb.Sp z‐scores (p < 0.001) indicating a different spacing distribution. Discussion: Relatively higher Tb.Th and BV/TV in the anterior calcaneus among gorillas likely reflects higher forces associated with body mass (transmitted through the subtalar joint) relative to forces transferred through the posterior calcaneus. The different Tb.Sp pattern in G. b. graueri may reflect proposed differences in foot positioning during locomotion. [ABSTRACT FROM AUTHOR]

Objectives: An accident during arboreal locomotion can lead to risky falls, but it remains unclear that the extent to which primates, as adept arborealists, change their locomotion in response to the perceived risk of moving on high supports in the tree canopy. By using more stable forms of locomotion on higher substrates, primates might avoid potentially fatal consequences. Materials and Methods: Using high‐speed cameras, we recorded the quadrupedal locomotion of four wild lemur species—Eulemur rubriventer, Eulemur rufifrons, Hapalemur aureus, and Lemur catta (N = 113 total strides). We quantified the height, diameter, and angular orientation of locomotor supports using remote sensors and tested the influence of support parameters on gait kinematics, specifically predicting that in response to increasing substrate height, lemurs would decrease speed and stride frequency, but increase stride length and the mean number of supporting limbs. Results: Lemurs did not adjust stride frequency on substrates of varying height. Adjustments to speed, stride length, and the mean number of supporting limbs in response to varying height often ran counter to predictions. Only E. rubriventer decreased speed and increased the mean number of supporting limbs on higher substrates. Discussion: Results suggest that quadrupedal walking is a relatively safe form of locomotion for lemurs, requiring subtle changes in gait to increase stability on higher—that is, potentially riskier—substrates. Continued investigation of the impact of height on locomotion will be important to determine how animals assess risk in their environment and how they choose to use this information to move more safely. Research Highlights: Substrate height can increase the risk of injury after a fall.Lemurs make subtle and variable adjustments to gait in response to substrate height.Substrate height will be important to include in future studies of wild primate locomotion. [ABSTRACT FROM AUTHOR]

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Objectives: Despite qualitative observations of wild primates pumping branches before leaping across gaps in the canopy, most studies have suggested that support compliance increases the energetic cost of arboreal leaping, thus limiting leaping performance. In this study, we quantified branch pumping behavior and tree swaying in wild primates to test the hypothesis that these behaviors improve leaping performance. Materials and Methods: We recorded wild colobine monkeys crossing gaps in the canopy and quantitatively tracked the kinematics of both the monkey and the compliant support during behavioral sequences. We also empirically measured the compliance of a sample of locomotor supports in the monkeys' natural habitat, allowing us to quantify the resonant properties of substrates used during leaping. Results: Analyses of three recordings show that adult red colobus monkeys (Piliocolobus tephrosceles) use branch compliance to their advantage by actively pumping branches before leaping, augmenting their vertical velocity at take‐off. Quantitative modeling of branch resonance periods, based on empirical measurements of support compliance, suggests that monkeys specifically employed branch pumping on relatively thin branches with protracted periods of oscillation. Finally, an additional four recordings show that both red colobus and black and white colobus monkeys (Colobus guereza) utilize tree swaying to cross large gaps, augmenting horizontal velocity at take‐off. Discussion: This deliberate branch manipulation to produce a mechanical effect for stronger propulsion is consistent with the framework of instrumental problem‐solving. To our knowledge, this is the first study of wild primates which quantitatively shows how compliant branches can be used advantageously to augment locomotor performance. [ABSTRACT FROM AUTHOR]

Gliding has evolved independently as an isolated adaptive event within many vertebrate taxa. Yet, the underlying selection forces that led to these innovative adaptations remain ambiguous, especially in species that preclude direct observation. Our study utilized accelerometry and machine learning algorithms to compare the behavioural repertoires of two sympatric species, the Mahogany glider (Petaurus gracilis) and brushtail possum (Trichosaurus vulpecula), as to explore previously proposed selection pressures such as energy expenditure (VeBA), canopy use and ground avoidance measured by activity budgets. We found that mahogany gliders on average expend more activity‐related energy than brushtail possums but at different stages throughout the day. Canopy use was observed to be greater amongst mahogany gliders than brushtail possums, and we observed frequent ground use in brushtail possums yet none in mahogany gliders. The study found strong evidence to support ground avoidance as a potential driver for gliding evolution. The implications of these findings are important when considering the lack of knowledge surrounding evolved gliding behaviours in marsupials. Furthermore, the use of accelerometers and machine learning algorithms in behavioural studies has proven to be a robust and informative method and should be incorporated into future studies to understand the evolution of gliding behaviour. [ABSTRACT FROM AUTHOR]

At what inclination does climbing begin? In this paper, we investigate the transition from walking to climbing in two species of parrot (Agapornis roseicollis and Nymphicus hollandicus) that are known to incorporate both their tail and their craniocervical system into the gait cycle during vertical climbing. Locomotor behaviors ranging in inclination were observed at angles between 0° and 90° for A. roseicollis, and 45°–85° degrees for N. hollandicus. Use of the tail in both species was observed at 45° inclination, and was joined at higher inclinations (> 65°) by use of the craniocervical system. Additionally, as inclination approached (but remained below) 90°, locomotor speeds were reduced while gaits were characterized by higher duty factors and lower stride frequency. These gait changes are consistent with those thought to increase stability. At 90°, A. roseicollis significantly increased its stride length, resulting in higher overall locomotor speed. Collectively these data demonstrate that the transition between horizontal walking and vertical climbing is gradual, incrementally altering several components of gait as inclinations increase. Such data underscore the need for further investigation into how exactly "climbing" is defined and the specific locomotor characteristics that differentiate this behavior from level walking. [ABSTRACT FROM AUTHOR]

Hypotheses have historically linked the emergence and evolution of defining human characteristics such as bipedal walking to ground-dwelling, envisioning our earliest ancestors as living in treeless savannahs (i.e. the traditional savannah hypothesis). However, over the last two decades, evidence from the fossil record combined with comparative studies of extant apes have challenged this hypothesis, instead favoring the importance of arboreality during key phases of hominin evolutionary history. Here we review some of these studies, including a recent study of savannah chimpanzees that provides the first model of how bipedalism could have been adaptive as an arboreal locomotor behavior in early hominins, even after the forests receded during the early Miocene-Pliocene transition. We suggest that whilst a shift to exploiting open habitats catalyzed hominin divergence from great apes, adaptations to arboreal living have been key in shaping what defines humans today, in counter to the traditional savannah hypothesis. Future comparative studies within and between great ape species will be instrumental to understanding variation in arboreality in extant apes, and thus the processes shaping human evolution over the last 3-7 million years. [ABSTRACT FROM AUTHOR]

It is thought arboreal species avoid foraging on the ground due to perceived predation risk, making the study of when and where arboreal species use the ground key in understanding foraging versus safety tradeoffs. We used publicly available, opportunistic, camera-trap observations from surveys across Madagascar to examine whether arboreal lemur ground use was spatially and temporally related to fosa (Cryptoprocta ferox), a native predator, and human presence. We observed 14 species of diurnal lemur (n = 287 individual observations) and six species of nocturnal lemur (n = 105 individual observations). With static two-species occupancy models and kernel density estimation, we found diurnal and nocturnal lemur ground use was spatially and temporally related to fosa presence. Diurnal lemurs used the ground less at camera locations where fosa were present compared to camera locations where they were absent, particularly if those camera locations lacked other native carnivores. Nocturnal lemurs used the ground more at camera locations fosa were observed at within the past 5 days compared with camera locations where fosa were not observed at within the past 5 days. Despite humans and diurnal lemurs being active at the same time 80% of the diel cycle (temporal overlap Δ = 0.80; 95% confidence interval [CI]: 0.75–0.85), diurnal lemur spatial or temporal use of the ground and human presence were unrelated. Diurnal lemur temporal overlap with humans at camera locations where fosa were uncommon was higher (Δ = 0.79; 95% CI: 0.71–0.86) compared with where fosa were common (Δ = 0.57; 95% CI: 0.46–0.66). Future research on how arboreal lemurs navigate ground use in a multipredator landscape should include behavioral observations to better understand animal decision-making. [ABSTRACT FROM AUTHOR]

ABSTRACTHypotheses have historically linked the emergence and evolution of defining human characteristics such as bipedal walking to ground-dwelling, envisioning our earliest ancestors as living in treeless savannahs (i.e. the traditional savannah hypothesis). However, over the last two decades, evidence from the fossil record combined with comparative studies of extant apes have challenged this hypothesis, instead favoring the importance of arboreality during key phases of hominin evolutionary history. Here we review some of these studies, including a recent study of savannah chimpanzees that provides the first model of how bipedalism could have been adaptive as an arboreal locomotor behavior in early hominins, even after the forests receded during the early Miocene-Pliocene transition. We suggest that whilst a shift to exploiting open habitats catalyzed hominin divergence from great apes, adaptations to arboreal living have been key in shaping what defines humans today, in counter to the traditional savannah hypothesis. Future comparative studies within and between great ape species will be instrumental to understanding variation in arboreality in extant apes, and thus the processes shaping human evolution over the last 3–7 million years.

Objectives: Differences in talar articular morphology relative to locomotion have recently been found within Pan and Gorilla. Whole‐bone talar morphology within, and shared variation among, Pan and Gorilla (sub)species, however, has yet to be investigated. Here we separately analyze talar external shape within Pan (P. t. troglodytes, P. t. schweinfurthii, P. t. verus, P. paniscus) and Gorilla (G. g. gorilla, G. b. beringei, G. b. graueri) relative to degree of arboreality and body size. Pan and Gorilla are additionally analyzed together to determine if consistent shape differences exist within the genera. Materials and Methods: Talar external shape was quantified using a weighted spherical harmonic analysis. Shape variation both within and among Pan and Gorilla was described using principal component analyses. Root mean square distances were calculated between taxon averages, and resampling statistics conducted to test for pairwise differences. Results: P. t. verus (most arboreal Pan) talar shape significantly differs from other Pan taxa (p < 0.05 for pairwise comparisons) driven by more asymmetrical trochlear rims and a medially‐set talar head. P. t. troglodytes, P. t. schweinfurthii, and P. paniscus do not significantly differ (p > 0.05 for pairwise comparisons). All gorilla taxa exhibit significantly different talar morphologies (p < 0.007 for pairwise comparisons). The more terrestrial subspecies of G. beringei and P. troglodytes exhibit a superoinferiorly taller talar head/neck complex. Discussion: P. t. verus exhibits talar morphologies that have been previously related to more frequent arboreality. The adaptations in the more terrestrial G. beringei and P. troglodytes subspecies may serve to facilitate load transmission. [ABSTRACT FROM AUTHOR]

Regionalization of the vertebral column can help animals adapt to different kinds of locomotion, including arboreal locomotion. Although functional axial regionalization has been described in both chameleons and arboreal mammals, no morphological basis for this functional regionalization in chameleons has been proposed. However, recent studies have described regionalization in the presacral vertebral column of other extant squamates. To investigate possible morphological regionalization in the vertebral column of chameleons, we took morphometric measurements from the presacral vertebrae of 28 chameleon species representing all extant chameleon genera, both fully arboreal and ground-dwelling, and performed comparative analyses. Our results support chameleons exhibiting three or four presacral morphological regions that correspond closely to those in other sauropsids, but we detected evolutionary shifts in vertebral traits occurring in only arboreal chameleons. Specifically, the anterior dorsal region in arboreal chameleons has more vertically oriented zygapophyseal joints, predicting decreased mediolateral flexibility. This shift is functionally significant because stiffening of the anterior thoracic vertebral column has been proposed to help bridge gaps between supports in primates. Thus, specialization of existing morphological regions in the vertebral column of chameleons may have played an important role in the evolution of extreme arboreal locomotion, paralleling the adaptations of arboreal primates.

Rhagomys is a genus of South American cricetids composed of three living species. They occur in eastern Andean and lowland tropical forests. Since description of this genus more than a century ago, it was treated as an enigmatic form within Sigmodontinae, varyingly thought to be allied to different suprageneric groups, with several scholars highlighting their presumptive autapomorphies. However, this morphologically based controversy was resolved with the advent of molecular data, indicating a weak affiliation to Thomasomyini. Here we resume the anatomical scrutiny of Rhagomys based on new evidence. New data, including CT-scan craniodental exploration and an ICAMER molar analysis, reinforce the uniqueness of this cricetid in the subfamily. In addition, we have enlarged and reworked the genetic data, composed of mitochondrial and nuclear markers, supporting not only the monophyly of Rhagomys , but also its resolution as a distinct branch of the sigmodontine radiation. To accommodate these results, we describe a new tribe for Rhagomys. The recognized clade is the most phenotypically differentiated of the Oryzomyalia and inaugurates a new arboreal morphotype. We hypothesize that Rhagomys has a set of anatomical features used to exploit understory resources by primarily insectivorous mice. [ABSTRACT FROM AUTHOR]

A key characteristic of primate above‐branch arboreal locomotion is hindlimb‐biased weight support, subverting the typical mammalian condition in which the majority of the body weight is supported by the forelimb. This shift is thought to reflect an adaptation toward the arboreal niches exploited by early primates. However, above‐branch quadrupedalism represents only one locomotor mode employed by primates in arboreal contexts. Inverted quadrupedal gaits, in which primates are suspended beneath branches by their hands and feet, have been documented in more than 50 primate taxa. This gait is characterized by a return to forelimb‐biased weight distributions and a transition from peak vertical forces being greatest in the hindlimb to being greatest in the forelimb, which may occur to protect the hindlimb from high magnitudes of tensile loading when inverted. In this study, we compare kinetic and kinematic data during upright and inverted quadrupedalism in Lemur catta, Varecia variegata, Cebus capucinus, and Saimiri sciureus. These data are referenced against a classical inverted quadrupedal model: the two‐toed sloth (Choloepus didactylus). Our findings show that inverted quadrupedalism in primates is differentiated from above‐branch quadrupedalism by increases in forelimb weight support, forelimb contact times, and both forelimb and hindlimb joint excursions. Previously postulated biomechanical models outlining mechanisms relating to the control of weight support during upright walking do not translate well to inverted quadrupedal walking. We suggest that inverted primates may simply be adopting basal neuromuscular gait characteristics and applying them facultatively to this infrequent locomotor behavior. Research Highlights: Inverted quadrupedalism has evolved several times in mammals, and is relatively widespread among primates. We compare kinematic and kinetic data during upright and inverted quadrupedal walking in four primate speciess, showing that inverted quadrupedalism is characterized by increases in forelimb weight support, forelimb contact times, and both forelimb and hindlimb joint excursions. [ABSTRACT FROM AUTHOR]

Abstract The interaction between morphology, performance, and ecology has long been studied in order to explain variation in the natural world. Within arboreal salamanders, diversification in foot morphology and microhabitat use are thought to be linked by the impact of foot size and shape on clinging and climbing performance, resulting in an ability to access new habitats. We examine whether various foot shape metrics correlate with stationary cling performance and microhabitat to explicitly quantify this performance gradient across 14 species of salamander, including both arboreal and nonarboreal species. Clinging performance did not correlate with foot shape, as quantified by landmark‐based geometric morphometrics, nor with microhabitat use. Mass‐corrected foot centroid size and foot contact area, on the other hand, correlated positively with clinging performance on a smooth substrate. Interestingly, these foot variables correlated negatively with clinging performance on rough substrates, suggesting the use of multiple clinging mechanisms dependent upon the texture of the surface. These findings demonstrate that centroid size and foot contact area are more functionally relevant for clinging in salamanders than foot shape, suggesting that foot shape need not converge in order to achieve convergent performance. More broadly, our results provide an example of how the quantification of the performance gradient can provide the appropriate lens through which to understand the macroevolution of morphology and ecology.

Harpesaurus tricinctus is an Asian agamid lizard described in 1851 from Java, Indonesia, and since then known only from its holotype located at the Paris Natural History Museum (MNHN-RA), supposedly a male, characterized by a long sickle-shaped rostral appendage. Ecological data are virtually lacking since no other specimen have ever been found. Here we review its morphology as compared with its congeners. We also review the morphology of other lizards and some snakes with rostral appendages and discuss their possible functional implications. We identified a South American dactyloid lizard, Anolis proboscis, the males of which show by their general habitus and a long, sword-shaped rostral appendage a striking convergence with the possibly extinct H. tricinctus. Anolis proboscis was also for long considered a rare and little-known lizard but recent field work allowing new observations provided additional data on its ecology. We suggest to use these new data on its habitat requirements which might be comparable to those of the externally so similar but allegedly extinct Indonesian agamid which might have survived in the canopy of tropical humid forests in one of the Greater Sunda Islands of Indonesia. [ABSTRACT FROM AUTHOR]

The interaction between morphology, performance, and ecology has long been studied in order to explain variation in the natural world. Within arboreal salamanders, diversification in foot morphology and microhabitat use are thought to be linked by the impact of foot size and shape on clinging and climbing performance, resulting in an ability to access new habitats. We examine whether various foot shape metrics correlate with stationary cling performance and microhabitat to explicitly quantify this performance gradient across 14 species of salamander, including both arboreal and nonarboreal species. Clinging performance did not correlate with foot shape, as quantified by landmark‐based geometric morphometrics, nor with microhabitat use. Mass‐corrected foot centroid size and foot contact area, on the other hand, correlated positively with clinging performance on a smooth substrate. Interestingly, these foot variables correlated negatively with clinging performance on rough substrates, suggesting the use of multiple clinging mechanisms dependent upon the texture of the surface. These findings demonstrate that centroid size and foot contact area are more functionally relevant for clinging in salamanders than foot shape, suggesting that foot shape need not converge in order to achieve convergent performance. More broadly, our results provide an example of how the quantification of the performance gradient can provide the appropriate lens through which to understand the macroevolution of morphology and ecology. [ABSTRACT FROM AUTHOR]

We describe a new species of Selvasaura from the montane forests of the eastern slopes of the Andes in northern Peru, based on external and hemipenial morphological characters and previous phylogenetic analyses. The new species can be differentiated from the other two Selvasaura species in having keeled dorsal scales usually flanked by longitudinal striations, in adults and juveniles; adult males with a yellow vertebral stripe bordered by broad dark brown stripes on each side and a unilobed hemipenis surrounded by the branches of the sulcus spermaticus. The description of the new species contributes information about new states of diagnostic characters of Selvasaura and natural history. [ABSTRACT FROM AUTHOR]

Abstract Background Previous analyses of factors influencing footfall timings and gait selection in quadrupeds have focused on the implications for energetic cost or gait mechanics separately. Here we present a model for symmetrical walking gaits in quadrupedal mammals that combines both factors, and aims to predict the substrate contexts in which animals will select certain ranges of footfall timings that (1) minimize energetic cost, (2) minimize rolling and pitching moments, or (3) balance the two. We hypothesize that energy recovery will be a priority on all surfaces, and will be the dominant factor determining footfall timings on flat, ground-like surfaces. The ability to resist pitch and roll, however, will play a larger role in determining footfall choice on narrower and more complex branch-like substrates. As a preliminary test of the expectations of the model, we collected sample data on footfall timings in a primate with relatively high flexibility in footfall timings – the squirrel monkey (Saimiri sciureus) – walking on a flat surface, straight pole, and a pole with laterally-projecting branches to simulate simplified ground and branch substrates. We compare limb phase values on these supports to the expectations of the model. Results As predicted, walking steps on the flat surface tended towards limb phase values that promote energy exchange. Both pole substrates induced limb phase values predicted to favor reduced pitching and rolling moments. Conclusions These data provide novel insight into the ways in which animals may choose to adjust their behavior in response to movement on flat versus complex substrates and the competing selective factors that influence footfall timing in mammals. These data further suggest a pathway for future investigations using this perspective.

Euspondylus excelsum was described from 8 specimens from the Region Huánuco in central Peru. We obtained an adult female from the Region Junín and a subadult male (photo vouchers only) from the Region Madre de Dios. Our new records of E. excelsum extend the range of this species by 592 km to the south and increase the previously known elevational range from 1023–1159 m a.s.l. to 550–1550 m a.s.l. The adult female is the largest known specimen extending the maximum SVL to 90.1 mm. Our findings indicate that E. excelsum is relatively widely distributed in the montane forests and foothills of the eastern Andes. Its arboreal mode of life is probably one reason for its rarity and limited records during traditional field surveys.

To date, there have been no studies that have evaluated small mammal utilization of the understory of forests. In this study, we described the use of vertical strata by small mammals in patches of unflooded forests, known as "cordilheiras", in the Nhecolândia sub-region of the Pantanal, Brazil. We collected all species using the ground and understory, including the terrestrial didelphid Monodelphis domestica. We suppose that local habitat features (e.g., Acuri palms), rather than intrinsic species characteristics, may be more conducive to the use of understory vegetation by small mammals in the Nhecolândia region. [ABSTRACT FROM AUTHOR]

Objectives: The primate foot has been extensively investigated because of its role in weight‐bearing; however, the calcaneus has been relatively understudied. Here we examine entire gorilla calcaneal external shape to understand its relationship with locomotor behavior. Materials and methods: Calcanei of Gorilla gorilla gorilla (n = 43), Gorilla beringei graueri (n = 20), and Gorilla beringei beringei (n = 15) were surface or micro‐CT scanned. External shape was analyzed through a three‐dimensional geometric morphometric sliding semilandmark analysis. Semilandmarks were slid relative to an updated Procrustes average in order to minimize the bending energy of the thin plate spline interpolation function. Shape variation was summarized using principal components analysis of shape coordinates. Procrustes distances between taxa averages were calculated and resampling statistics run to test pairwise differences. Linear measures were collected and regressed against estimated body mass. Results: All three taxa exhibit statistically different morphologies (p <.001 for pairwise comparisons). G. g. gorilla demonstrates an anteroposteriorly elongated calcaneus with a deeper cuboid pivot region and mediolaterally flatter posterior talar facet. G. b. beringei possesses the flattest cuboid and most medially‐angled posterior talar facets. G. b. graueri demonstrates intermediate articular facet morphology, a medially‐angled tuberosity, and an elongated peroneal trochlea. Discussion: Articular facet differences separate gorillas along a locomotor gradient. G. g. gorilla is adapted for arboreality with greater joint mobility, while G. b. beringei is adapted for more stereotypical loads associated with terrestriality. G. b. graueri's unique posterolateral morphology may be due to a secondary transition to greater arboreality from a more terrestrial ancestor. [ABSTRACT FROM AUTHOR]

Climbing animals theoretically should optimize the energetic costs of vertical climbing while also maintaining stability. Many modifications to climbing behaviors have been proposed as methods of satisfying these criteria, focusing on controlling the center of mass (COM) during ascent. However, the link between COM movements and metabolic energy costs has yet to be evaluated empirically. In this study, we manipulated climbing conditions across three experimental setups to elicit changes in COM position, and measured the impact of these changes upon metabolic costs across a sample of 14 humans. Metabolic energy was assessed via open flow respirometry, while COM movements were tracked both automatically and manually. Our findings demonstrate that, despite inducing variation in COM position, the energetic costs of climbing remained consistent across all three setups. Differences in energetic costs were similarly not affected by body mass; however, velocity had a significant impact upon both cost of transport and cost of locomotion, but such a relationship disappeared when accounting for metabolic costs per stride. These findings suggest that climbing has inescapable metabolic demands driven by gaining height, and that attempts to mitigate such a cost, with perhaps the exception of increasing speed, have only minimal impacts. We also demonstrate that metabolic and mechanical energy costs are largely uncorrelated. Collectively, we argue that these data refute the idea that efficient locomotion is the primary aim during climbing. Instead, adaptations towards effective climbing should focus on stability and reducing the risk of falling, as opposed to enhancing the metabolic efficiency of locomotion., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2024. Published by The Company of Biologists Ltd.)

Disturbance shapes ecological communities. Frequency, predictability, and intensity characterize disturbances, which select for resistant and/or resilient traits of species. Unpredictable and infrequent disturbance events, especially those with no reliable cues, lack selection strength and have less calculable effects on species assemblages and trait-based species sorting. In a flood plain in Northeast Costa Rica, across sites with varying flood frequency and no reliable cues to signal flooding, we used ants as a focal taxon to assess the impact of disturbance on ant activity and species assemblage. We examined activity patterns such as extent of occupancy of baits and nesting guild (i.e. strata used) that might mediate the effects of stochastic flood events. We hypothesized that the ant community in the most frequently flooded site would be dominated by above-ground nesting ants whose nesting traits make them resilient to inundation. The site with the most frequent flooding had the lowest level of ant presence on baits and differed in species assemblage, as demonstrated by the analysis of similarity, compared with the sites with lower flooding frequency. Neither overall species richness nor richness of species in the above-ground nesting guild differed between sites. However, nesting in trees above flood waters may be beneficial to escape frequent and unreliable flooding of habitats, and, as we hypothesized, there was greater activity of above-ground nesting ants compared with ground nesting ants in the most frequently flooded site. These differences in nesting guilds were diminished in the drier sites. [ABSTRACT FROM AUTHOR]

Abstract Background Various factors, such as climate, body size and sociality are often linked to parasitism. This constrains the identification of other determinants driving parasite infections. Here, we investigate for the first time intestinal parasites in two sympatric arboreal primate species, which share similar activity patterns, feeding ecology, body size and sociality, and cope with the same climate conditions, but differ in sleeping site ecology: the Milne-Edward’s sportive lemur (Lepilemur edwardsi) and the Western woolly lemur (Avahi occidentalis). Comparison of these two species aimed to test whether differences in sleeping sites are related to differences in parasite infection patterns. Additionally, gender and seasonal factors were taken into account. Animals were radio-collared to record their sleeping site dynamics and to collect fecal samples to assess intestinal parasitism during both the dry and the rainy season. Results Only low parasite diversity was detected, which is attributable to the strict arboreal lifestyle of these lemurs, limiting their contact with infective parasite stages. L. edwardsi, which sleeps in tree holes and repeatedly uses the same sleeping site, excreted eggs of strongyle and oxyurid nematodes, whereby strongyles always occurred in coinfection with oxyurids. In contrast, A. occidentalis, which sleeps on open branches and frequently changes sleeping sites, only excreted eggs of strongyle nematodes. This difference can be attributed to a potential favorable environment presented by tree holes for infective stages, facilitating parasitic transmission. Additionally, Strongylida in A. occidentalis were only observed in the rainy season, suggesting an arrested development during the dry season in the nematodes’ life cycle. Males and females of both lemur species showed the same frequency of parasitism. No differences in body mass of infected and non-infected individuals were observed, indicating that the animals’ body condition remains unaffected by the detected gastrointestinal parasites. Conclusions The comparison of two primate hosts with a very similar lifestyle suggests an influence of the sleeping site ecology on intestinal parasites. In A. occidentalis there was a clear seasonal difference in strongyle egg excretion. These results improve our understanding of the parasite ecology in these endangered primate species, which may be critical in the light of species conservation.

During camera-trapping surveys for arboreal mammals within Yellingbo Nature Conservation Reserve we recorded arboreal behaviour in the mainland dusky antechinus, which is typically regarded as a strictly terrestrial species. The species was detected visiting baits positioned ~3.5 m high on trees on 29 occasions, providing additional evidence of arboreal behaviour in the species and further demonstrating the value of camera traps in providing novel insights into animal behaviour. [ABSTRACT FROM AUTHOR]

In tropical forests, epiphytes increase habitat complexity and provision services rare to canopy environments, such as water retention, nutrient cycling, and microclimate refuge. These services facilitate species diversity and coexistence in terrestrial ecosystems, and while their utility in forest ecosystems is appreciated for the Bromeliaceae of the Neotropics, fewer studies have examined the role of Paleotropic epiphytes in ecological niche theory. Here, we compare herpetofaunal presence, abundance, and diversity of in bird's nest fern (Asplenium nidus complex; BNF) to other microhabitats in Madagascar and the Philippines. We measure BNF fern microclimates, examine temporal use of canopy microhabitats, and test models of fern characteristics hypothesized to predict herpetofaunal use. In both countries, one in five BNFs were occupied by herpetofauna, mostly amphibians, and species using BNFs were highly dissimilar from those in other microhabitats. Herpetofaunal presence and abundance were greater in BNFs than in other canopy microhabitats and were most commonly used during the day when fern temperatures were highly buffered. Finally, BNF area was the best predictor of herpetofaunal presence and abundance, compared to canopy cover and BNF height. Importantly, these patterns remained consistent despite the distinct phylogenetic histories of our two communities (Asian versus African). Our results suggests that BNFs and their microclimate services play a critical role in the ecology of two Paleotropic forests, and facilitate the use of canopy habitats by climate-sensitive species. However, future studies are needed to assess the consistency of BNFs' utility as a microclimate refuge across their large range. [ABSTRACT FROM AUTHOR]

Evolutionary innovations and ecological competition are factors often cited as drivers of adaptive diversification. Yet many innovations result in stabilizing rather than diversifying selection on morphology, and morphological disparity among coexisting species can reflect competitive exclusion (species sorting) rather than sympatric adaptive divergence (character displacement). We studied the innovation of gliding in dragons (Agamidae) and squirrels (Sciuridae) and its effect on subsequent body size diversification. We found that gliding either had no impact (squirrels) or resulted in strong stabilizing selection on body size (dragons). Despite this constraining effect in dragons, sympatric gliders exhibit greater size disparity compared with allopatric gliders, a pattern consistent with, although not exclusively explained by, ecological competition changing the adaptive landscape of body size evolution to induce character displacement. These results show that innovations do not necessarily instigate further differentiation among species, as is so often assumed, and suggest that competition can be a powerful force generating morphological divergence among coexisting species, even in the face of strong stabilizing selection. [ABSTRACT FROM AUTHOR]

We describe a new species of Crocidura (Soricidae) from Sulawesi Island, Indonesia, documenting its novelty with both genetic and morphological characters. The new species is widespread on the island, with vouchered records from nine general localities distributed among five of the island's areas of endemism. Morphologically, the new species is readily distinguished from all other described Sulawesi Crocidura by its intermediate body size, gray pelage, and long, hairy tail. The new species was mainly captured in pitfalls placed in the ground, but we also obtained evidence that it readily climbs trees and may be scansorial in its locomotor habits. Populations of the new species sampled from across the island are closely related, separated by < 0.02 uncorrected mitochondrial p -distances. The new species is one member of an endemic radiation of shrews on Sulawesi now known to contain six valid species and several undescribed species, all within the genus Crocidura. Resolution of species limits and phylogenetic relationships in this radiation is hindered by habitat loss at type localities, historical designation of new species using very small sample sizes, and a lack of genetic data from type specimens. Kami mendeskripsikan spesies baru Crocidura (Soricidae) dari Pulau Sulawesi, Indonesia, sekaligus mendokumentasikan keunikan karakter secara genetik maupun morfologi dari spesies tersebut. Spesies baru ini tersebar luas di Pulau Sulawesi, diketahui berdasarkan spesimen yang berasal dari sembilan lokasi umum yang tersebar di lima kawasan endemik di pulau tersebut. Secara morfologi, spesies baru ini dapat dibedakan dari spesies Crocidura lainnya dari Sulawesi berdasarkan ukuran tubuh yang sedang, rambut tubuh berwarna abu-abu, dan ekor yang panjang dan berambut. Spesies baru ini sebagian besar diperoleh dari perangkap sumuran yang ditanam didalam tanah, selain itu kami juga mendapatkan bukti bahwa spesies ini mampu memanjat pohon dan kemungkinan memiliki perilaku sebagai pemanjat. Beberapa populasi spesies yang dikoleksi dari Sulawesi ini mempunyai kekerabatan yang dekat, hanya dipisahkan oleh jarak proporsi DNA mitokondria (tidak terkoreksi) sebesar < 0.02. Spesies baru ini merupakan salah satu anggota dari suatu kelompok radiasi endemik cecurut di Sulawesi yang sampai saat ini diketahui terdiri atas enam spesies yang valid, dan beberapa spesies yang belum dideskripsikan, semuanya termasuk didalam genus Crocidura. Kepastian dalam menetapkan batasan jarak antar spesies dan hubungan kekerabatan genetik dari radiasi kelompok cecurut di Sulawesi terkendala oleh kerusakan habitat pada lokasi spesimen tipe, sejarah penamaan spesies yang hanya berdasarkan sampel yang sedikit, dan keterbatasan data molekuler dari spesimen tipe. [ABSTRACT FROM AUTHOR]

Previous behavioral reports of the African lorisid, Perodicticus potto, have speculated that these animals have an extraordinary grip strength. This ability is hypothesized to be facilitated by a range of anatomical features within the forelimb, ranging from the presence of a retia mirabilia in its wrist to the hyper‐abduction of its pollex. Despite numerous behavioral reports, however, this claim of extraordinary grip strength has not been empirically substantiated. This study quantifies the physiological cross‐sectional area of the digital flexor muscles within P. potto. These data are compared with a broad primate sample, including several similarly sized strepsirrhines. Contrary to expectation, we found that P. potto actually has relatively below‐average digital flexor PCSA. However, we identified other myological characteristics in the upper limb of P. potto that were unexpected, including the largest brachioradialis muscle (an elbow flexor) among our primate sample, and – despite P. potto having only a vestigial second digit – an independent digital extensor indicis that is absent in almost a quarter of our primate sample. [ABSTRACT FROM AUTHOR]

The pandemic disease chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd), is a major threat to amphibian biodiversity. For most species, the exact mechanisms of chytridiomycosis that lead to negative population dynamics remain uncertain, though mounting evidence suggests that sublethal effects could be an important driver. In this review, we propose that tree frog attachment is a promising case to study the sublethal effects of a Bd infection on amphibians. A synthesis of the current knowledge on the functional morphology of the adhesive toe pads of tree frogs, on the underlying mechanisms of tree frog attachment, and on the epidermal pathology of chytridiomycosis substantiates the hypothesis that Bd-induced epidermal alterations have the potential to disrupt tree frog attachment. We highlight a series of (biomechanical) experiments to test this hypothesis and to shed some light on the sublethal disease mechanisms of chytridiomycosis. The knowledge generated from such an approach could contribute to future research on Bd epidemiology and ultimately to the conservation of the biodiversity of arboreal anurans.

Brain enlargement is an adaptation in animals that use the space in three dimensions and need to integrate information of complex environments. As consequence, this adaptation can result in differences in skull shape among species with different types of locomotion and level of arboreality. We directly tested for the relation between the cranial shape and arboreality (based on field data) of 11 Sigmodontinae rodent species from a Neotropical savanna (Cerrado). For that, we used geometric morphometrics considering both dorsal and lateral views of the cranium. We also accounted for any possible allometric effects (i.e. the relationship between size and shape) and evolutionary constraints (i.e. phylogenetic signal) on the cranial shape. The dorsal view presented strong allometric effects but no phylogenetic signal. On the other hand, the lateral view showed a weak allometric effect and a significant phylogenetic signal. After controlling for size and evolutionary constraints, we found significant relationships between rodent arboreality and cranial shape for both lateral (r2 = 0.74) and dorsal cranium views (r2 = 0.40). Patterns for both views showed that arboreal rodents present more expanded crania, suggesting larger brains. The dorsal view showed a general cranial expansion in arboreal rodents, whereas the lateral view showed a more rounded and posteriorly expanded cranium. This later suggests a larger cerebellum, an important brain portion responsible for orientation and sense of balance. Our study provides evidence that the cranial shape can be used as a proxy to infer arboreal activity of sigmodontine rodents. Moreover, the observed differences in cranial shape between arboreal and terrestrial species are probably related to brain enlargement in the former driven by the need to cope with a three‐dimensional environment. [ABSTRACT FROM AUTHOR]

Abstract Plesiadapiforms, like other Paleogene mammals, are known mostly from fossil teeth and jaw fragments. The several families of plesiadapiforms known from partial skeletons have all been reconstructed as arborealists, but differences in postcranial morphology among these taxa indicate a diversity of positional behaviors. Here we provide the first detailed descriptions and comparisons of a dentally associated partial skeleton (NMMNH P-54500) and of the most complete dentary with anterior teeth (NMMNH P-71598) pertaining to Torrejonia wilsoni , from the early Paleocene (late Torrejonian To3 interval zone) of the Nacimiento Formation, San Juan Basin, New Mexico, USA. NMMNH P-54500 is the oldest known partial skeleton of a plesiadapiform and the only known postcrania for the Palaechthonidae. This skeleton includes craniodental fragments with all permanent teeth fully erupted, and partial forelimbs and hind limbs with some epiphyses unfused, indicating that this individual was a nearly fully-grown subadult. Analysis of the forelimb suggests mobile shoulder and elbow joints, a habitually flexed forearm, and capacity for manual grasping. The hip joint allowed abduction and lateral rotation of the thigh and provides evidence for frequent orthograde postures on large diameter supports. Other aspects of the hind limb suggest a habitually flexed thigh and knee with no evidence for specialized leaping, and mobile ankle joints capable of high degrees of inversion and eversion. Although it is likely that some variability exists within the group, analysis of this skeleton suggests that palaechthonids are most like paromomyids among plesiadapiforms, but retain more plesiomorphic postcranial features than has been documented for the Paromomyidae. These observations are congruent with craniodental evidence supporting palaechthonids and paromomyids as closely related within the Paromomyoidea. The skeleton of T. wilsoni also demonstrates that many regions of the postcranium were already well adapted for arboreality within the first few million years of the diversification of placental mammals following the Cretaceous-Paleogene extinction event. [ABSTRACT FROM AUTHOR]

We describe a new arboreal genus and species of the family Gymnophthalmidae, subfamily Cercosaurinae, from Peru on the basis of genetic and morphological characters. Dendrosauridion gen. n. can be distinguished morphologically from all other genera of Cercosaurinae by having the lower palpebral disc transparent and undivided, dorsal scales smooth, lateral scales distinctly smaller than dorsal scales, and lateral scales adjacent to ventrals non-granular, not forming a distinct longitudinal line along body axis. Phenotypic synapomorphies are not known for the new genus. In a previously published phylogeny, Dendrosauridion gen. n. was identified as a distinct clade separated from all other cercosaurines. The monotypic genus contains Dendrosauridion yanesha sp. n., which is known from two localities in montane forests of the eastern Andes in central (Region Pasco) and southern Peru (Region Cusco) from 2780 to 2825 m a.s.l. with a distributional gap of 413 km in between. The two adult males (SVL 59.1-60.2 mm) and one juvenile were found in trees. The secretive habits of D. yanesha sp. n. are likely the reason for its rarity and we propose the threat status of the new species as "Data Deficient." [ABSTRACT FROM AUTHOR]

To better understand the relationship between forest complexity and small mammal diversity, we investigated the vertical stratification of marsupials and rodents in 2 forest types with distinct levels of complexity in a Neotropical savanna (Brazilian Cerrado). We livetrapped mammals in gallery forests and the less-complex savanna woodland forests (locally known as "cerradão") at ground level, in the understory (1–4 m above ground), and in the canopy (7–19 m above ground), for a total of 43,200 trap-nights. We recorded 1,335 captures of 682 individuals (4 marsupial and 7 rodent species). We compared alpha and beta diversity between forest formations evaluating the effect of sampling in multiple vertical strata on estimates of species richness, and determining species turnover among the vertical strata. Our results showed that species associations with specific vertical strata differed between forest types. Alpha diversity of the gallery forest was greater than that of the savanna woodland forest, but in both forest formations, estimates of species richness increased when all 3 vertical strata were considered. In addition, species turnover among vertical strata was higher in gallery forests than in savanna woodland forests. Our results show the importance of sampling at different heights in complex environments to obtain more reliable estimates of species richness and abundance. Furthermore, our study provides evidence for the role of environmental complexity in the vertical stratification of small mammals, with increased alpha and beta diversity in more complex environments likely due to niche subdivision. [ABSTRACT FROM AUTHOR]

Locomotor diversity has meant many different things depending on the subject area or investigator. While no concrete definition of locomotor diversity is currently available, this has not stopped researchers from making a number of assertions about the underlying mechanisms that determine whether a species will have high or low locomotor diversity. Some of these claims include that: (1) arboreal primates demonstrate higher locomotor diversity than terrestrial species; (2) anatomically generalized and small‐bodied primates demonstrate higher locomotor diversity than anatomically specialized and large‐bodied taxa; and (3) primates demonstrate higher locomotor diversity compared to non‐primate mammals. None of these claims have been tested in any sort of comparative framework. Using previously published locomotor repertoire data from 110 mammalian species, this study co‐opted the Shannon–Wiener diversity index to calculate a singular measure of locomotor diversity. Phylogenetic analyses of these locomotor diversity indices reveal that within primates, small‐bodied species demonstrate greater locomotor diversity than large‐bodied taxa. However, this effect becomes non‐significant when accounting for differences in substrate‐use (i.e. arboreal vs. terrestrial). Anatomical specialization has no effect on locomotor diversity in primates. Furthermore, primates do not inherently have greater locomotor diversity than other mammalian taxa. Findings from this study suggest that movement on arboreal substrates requires all mammals, regardless of taxonomic affiliation, to demonstrate high locomotor diversity. These data further highlight the challenges faced by arboreal animals and raise the possibility that being able to switch fluidly and frequently between many different locomotor modes may be advantageous for animals moving in an arboreal milieu. Locomotor diversity has meant many different things depending on the subject area or investigator, but there is no concrete definition of locomotor diversity currently available. Using previously published locomotor repertoire data from 110 mammalian species, this study co‐opted the Shannon–Wiener diversity index to calculate a singular measure of locomotor diversity. Phylogenetic analyses of these locomotor diversity indices reveal that within primates, small‐bodied species demonstrate greater locomotor diversity than large‐bodied taxa. Furthermore, primates do not inherently have greater locomotor diversity than other mammalian taxa. Findings from this study suggest that movement on arboreal substrates requires all mammals, regardless of taxonomic affiliation, to demonstrate high locomotor diversity. These data further highlight the challenges faced by arboreal animals and raise the possibility that being able to switch fluidly and frequently between many different locomotor modes may be advantageous for animals moving in an arboreal milieu. [ABSTRACT FROM AUTHOR]

Euspondylus excelsum was described from 8 specimens from the Region Huánuco in central Peru. We obtained an adult female from the Region Junín and a subadult male (photo vouchers only) from the Region Madre de Dios. Our new records of E. excelsum extend the range of this species by 592 km to the south and increase the previously known elevational range from 1023-1159 m a.s.l. to 550-1550 m a.s.l. The adult female is the largest known specimen extending the maximum SVL to 90.1 mm. Our findings indicate that E. excelsum is relatively widely distributed in the montane forests and foothills of the eastern Andes. Its arboreal mode of life is probably one reason for its rarity and limited records during traditional field surveys. [ABSTRACT FROM AUTHOR]

The Clarkia lagerstätte (Latah Formation) of Idaho is well known for its beautifully preserved plant fossils as well as a fauna of insects and fish. Here we present the first known tetrapod fossil from these deposits. This specimen, recovered from the lower anoxic zone of the beds, is preserved as a carbonaceous film of a partial skeleton associated with a partial lower incisor and some tooth fragments. The morphology of the teeth indicates that the first tetrapod reported from Clarkia is a rodent. Its skeletal morphology as well as its bunodont and brachydont dentition suggests that it is a member of the squirrel family (Sciuridae). It is a large specimen that cannot be assigned to a known genus. Instead, it appears to represent the first occurrence of a new taxon with particularly gracile postcranial morphology likely indicative of an arboreal ecology. This new specimen is a rare glimpse into the poorly known arboreal mammal fossil record of the Neogene. It supports a greater taxonomic and ecological diversity of Miocene Sciuridae than previously recognized and offers new lines of inquiry in the paleoecological research enabled by the unique preservation conditions of the Clarkia biota.

Across tetrapods, the proportional lengths of the manual and pedal phalanges are highly constrained, following a generalized blueprint of shortening in a proximodistal gradient. Despite this, several lineages of both mammals (e.g. sloths, bats and colugos) and birds (e.g. raptors, parrots and woodpeckers) have broken this pattern, shortening the proximal phalanx while elongating more distal elements. As yet, no unifying explanation for this convergence has been empirically evaluated. This study combines a comparative phylogenetic assessment of phalangeal morphology across mammals and birds with a novel bioinspired robotics approach to explicitly test functional hypotheses relating to these morphotypes. We demonstrate that shortening the proximal phalanx allows taxa to maximize forces produced at the proximal interphalangeal joint, while elongation of subsequent elements maintains total ray length-ensuring arboreal species can still enclose large-diameter supports. Within suspensory and vertically clinging mammals, we additionally observe a secondary adaptation towards maximizing grip strength: namely increasing the height of the trochleae to increase the moment arm of digital flexor muscles that cross the joint. Together, our analyses highlight that numerous tetrapod lineages independently converged upon this morphotype to maximize proximal gripping strength, an adaptation to support specialized hunting and locomotor behaviours.

The arboreal environment is complex and irregular and imposes significant constraints on the locomotor ability of vertebrates, resulting in morphological adaptations. Carnivorans are of particular interest because they radiated several times independently into the arboreal milieu, leading to convergence in long bone anatomy. We investigated whether the forelimb muscles show differences in arboreal vs. terrestrial species and tested for convergence in muscle architecture. To do so, we studied the forelimb muscles in 17 species of carnivorans with different locomotor modes (arboreal and terrestrial). Our results showed that the forelimb musculature evolved in a convergent manner in arboreal species, resulting in more forceful and heavier wrist rotators and elbow flexors, even when accounting for phylogeny. This suggests that selective forces imposed by the environment drive the evolution of the muscular system towards a convergent phenotype that provides a functional advantage for locomotion in the complex three-dimensional arboreal habitat. [ABSTRACT FROM AUTHOR]

Cercosaurine lizards (subfamily Cercosaurinae of the family Gymnophthalmidae) represent a substantial component of the reptile fauna in the Neotropics. Several attempts have been made to reconstruct the phylogenetic relationships within this group, but most studies focused on particular genera or regions and did not cover the subfamily as a whole. In this study, material from the montane forests of Peru was newly sequenced. In combination with all cercosaurine sequences available on GenBank, an updated phylogeny of Cercosaurinae is provided. Monophyly was not supported for three of the currently recognised genera (Echinosaura, Oreosaurus, and Proctoporus). The genus Proctoporus is formed by five monophyletic groups, which should be used in future taxonomic revisions as feasible entities. Recognition of two previously identified undescribed clades (Unnamed clades 2 and 3) was supported and yet another undescribed clade (termed here Unnamed clade 4), which deserves recognition as an independent genus, was identified herein. Selvasaura brava, a new genus and new species of arboreal gymnophthalmid lizard is described from the montane forests of the Pui Pui Protected Forest, Provincia de Chanchamayo, Región Junín, Peru. The new species is characterised by its small size (SVL 42.1-45.9 mm), slender body, smooth head shields, presence of paired prefrontal shields, fused anteriormost supraocular and anteriormost superciliary shields, transparent not divided lower palpebral disc, slightly rugose subimbricate rectangular dorsal scales in adults (slightly keeled in juveniles), distinctly smaller but non-granular lateral scales, smooth squared to rectangular ventral scales, and hemipenial lobes large, distinct from the hemipenial body. Phylogenetic affinities of the new genus to the other cercosaurine genera, as well as basal phylogenetic relationships between the other cercosaurine genera remain unresolved. [ABSTRACT FROM AUTHOR]

Climbing is integral to scansorial and arboreal lifestyles as it enables access to and vertical ranging within the arboreal strata. As early eutherian mammals exhibit osteological correlates for arboreality, it is important to assess the behavioral mechanisms that are related to competent vertical climbing. In this context, we examined climbing gaits in one of the smallest extant rodents, the Eurasian harvest mouse. For these purposes, we filmed six adult Micromys minutus at 240 fps moving on four different substrate sizes (2 mm, 5 mm, 10 mm, 25 mm), during both vertical ascents and descents. All climbing cycles were lateral sequence slow gaits. Upward climbing was characterized by a higher contribution of the hind limbs, longer swing phases, and a significant involvement of stride frequency in velocity modulation. On the other hand, downward climbing was promoted by employing gaits of even lower diagonality, an increased contact with the substrate, enhanced role of the forelimbs, and a subtler modulation of velocity by stride frequency. Eurasian harvest mice effectively negotiate the finest substrates, but their effectiveness decreased significantly on the largest ones. The morphofunctional similarities of M. minutus to Juramaia sinensis and Eomaia scansoria imply analogous behaviors in early eutherians, which apparently contributed to the successful access and exploitation of the fine-branch arboreal milieu. In this way, extant small arboreal mammals can constitute good models for elucidating and comprehending the adaptive significance of behavioral mechanisms that are related to the evolution of arboreality in early mammals. [ABSTRACT FROM AUTHOR]