Leandro Rabello Monteiro

Sexual dimorphism is a common source of intraspecific variation among carnivorans. Although indirect sexual selection on a particular trait can lead to sexual dimorphism in others, the effects of cross-trait covariances on carnivoran mandibular morphology remain understudied, especially in more generalist species, such as the South American Coati Nasua nasua. Herein, we asked whether sexual shape dimorphism (SShD) in the mandible of N. nasua—which presents strong male-biased sexual selection—were biased to sexual size dimorphism (SSD). Based on analyses of 148 adult specimens, we found that male coatis exhibited mandibles 10% larger and typically more robust than females, with lengthier canines and proportionally shorter molar tooth rows. While allometry intensified this SShD, sex-related differences also persisted in its nonallometric shape. These differences were mostly concentrated to the anterior portion of the mandibular corpus, where canines are attached. Because male coatis use their atypically enlarged canines during combat, we hypothesized that these differences were primarily related to male-biased sexual selection, leading to trade-offs in the relative proportions of canines relative to molars. These results indicate that mandibular SShD in N. nasua is not merely a by-product of SSD, but it also reflects direct male-biased sexual selection on combat-related traits.

Natural history collections serve as crucial infrastructure for both basic and applied scientific research, providing temporal and spatial specimen data needed to understand biodiversity, environmental change, and emerging pathogens. This study surveyed mammal collections across South America to assess the scope and quality of this infrastructure. A detailed questionnaire was distributed to curators and collection managers from May 2021 to February 2022, gathering information on institutional characteristics, collection size, taxonomic and geographical scope, preservation methods, genetic resource availability, percentage digitization, financial support, and challenges such as funding limitations. Our survey identified 141 collections; more than twice the number reported by the American Society of Mammalogists in 2018. South American collections house ∼746 000 catalogued specimens, including 452 primary type specimens, representing only a modest proportion of the vast mammalian diversity of South America. Collections are geographically concentrated in Argentina, Brazil, Colombia, and Peru, with a significant gap in the Guianas region and a decline in responses from Venezuela. The survey highlights four major challenges facing South American collections: staffing shortages, minimal cryogenic infrastructure, incomplete digitization, and sustainability issues. This initiative aims to raise awareness of collections in South America, plan for strategic growth, and strengthen research capacity to address pressing global issues, such as climate change, zoonotic disease transmission, and long-term conservation strategies.

Uroderma magnirostrum Davis, 1968, the Brown Tent-making Bat, is a medium-sized frugivorous phyllostomid. It is characterized by poorly defined facial and dorsal stripes, large bifid upper inner incisors, and a laterally expanded mesethmoid bone. Uroderma magnirostrum is widely distributed between western Mexico and southeastern Brazil, and across its distribution, it inhabits different types of environments (e.g., pristine tropical forests; farmlands; mangroves; savannas; urban green areas). It is listed as “Least Concern” (LC) by the International Union for Conservation of Nature and Natural Resources but appears in national red lists, such as those from Guatemala and Nicaragua, due to the significant impact of the human activities in these countries.

Developmental instability (DI) is a phenomenon whereby organisms are unable to buffer developmental disturbances, resulting in asymmetric variation of paired traits. Previous research has demonstrated a negative relationship between DI, measured as forearm asymmetry, and survival in the bat Carollia perspicillata. This study aims to test the hypothesis that individuals with higher DI exhibit a lower immune response. We measured a delayed-type hypersensitivity to the antigen phytohemagglutinin (PHA) on 74 males and 65 females of C. perspicillata before and after the breeding season. Linear models were used to predict the immunological response based on body mass, forearm asymmetry, sex, breeding season, and testicle length. The best-fitting model accounted for 29% of the variation in immune response and included asymmetry, body mass, sex, and breeding season as predictors. The immune response was negatively associated with asymmetry and testicle length in males, but positively related to asymmetry in females. Both sexes showed a reduced immune response in the late breeding season. Additionally, the association between immune response and body mass changed direction seasonally, with heavier individuals showing weaker responses early in the breeding season and stronger responses later. Individual variation in male immunity was predicted by individual attributes, whereas variation in immune response in females was mostly seasonal. Our results support the link between DI, survival, and immune response in short-tailed bats, and suggest that the immunological component measured by the PHA response may be under finer selection in males due to its stronger correlation with individual traits.

We describe the first known case of disproportionate dwarfism in bats. The specimen is an adult male Seba’s short-tailed bat, Carollia perspicillata (Linnaeus, 1758), captured in a ground-level mist net during a survey in a lowland Atlantic Forest area in southeastern Brazil. Examination of the specimen skull showed craniofacial anomalies, including microdontia in the upper incisors, oligodontia in the third upper molars, fusion of the nasal septum and the left ventral nasal concha, and a narrower foramen magnum. Post-cranial changes were mainly related to shortened radius, tibia, and metacarpals, compared to the reference sample in multivariate space. Given its unusual morphology with short wings and average body mass, the dwarf would have higher wing loading, fly faster, require more power to fly, and have a shorter flight range compared to the species pattern. Because it presented good body condition and reached adulthood, possible mechanisms of functional compensation are discussed.

Studies on functional performance are important to understand the processes responsible for the evolution of diversity. Morphological trait variation within species influences the energetic cost of locomotion and impacts life history traits, with ecological and evolutionary consequences. This study examined wing morphology correlates of flight performance measured by energetic expenditure in the Seba's short‐tailed bat, Carollia perspicillata. In the flight experiments, nature caught bats (59 females, 57 males) were allowed to fly for 3 min in a room. After each flight, thermographic images were taken to measure body temperature, and biophysical models were used to calculate sensible heat loss as a measure of energetic expenditure. Wing morphological traits were measured for each individual and associated with heat loss and power required to fly on performance surfaces. Wing morphological traits explained 7–10% of flight energetic cost, and morphologies with the best performance would save the energy equivalent to 9–30% of total daily requirements. The optimal performance areas within the C. perspicillata morphospace were consistent with predicted selection trends from the literature. A trade‐off between demands for flight speed and maneuverability was observed. Wing loading and camber presented sexual dimorphism. These morphological differences are likely associated with more economical but less maneuverable flight in females, leading them to fly more often in open areas along the forest edge. Our findings demonstrate how small scale changes in wing morphology can affect life history strategies and fitness.

Sturnira tildae de la Torre, 1959, Tilda’s yellow-shouldered bat, is a phyllostomid with wide geographic distribution across South America. It inhabits preferably lowland mature rainforests, but also has been captured in modified vegetation and tropical savannas, where it is less abundant. Globally, it is listed as “Least Concern” (LC) by the International Union for Conservation of Nature and Natural Resources, but local red lists in southern Brazil have recorded this species as “Vulnerable,” mainly due to habitat destruction (Atlantic Forest deforestation).

The individual identification of animals is essential for long-term population ecology studies. Injuries and tag loss can negatively impact animal welfare and parameter estimates. We used time-to-failure curves and multistate mark-recapture models to estimate injury rates, body condition decline, tag loss and survival probabilities associated with two tags commonly used in bats: metallic arm bands and steel ball chain collars. We monitored two colonies of Carollia perspicillata at União Biological Reserve, southeastern Brazil, from 2013 to 2019. Every other month, we marked individuals with arm bands, collars or both. Collars did not cause noticeable injuries, but were lost at a higher rate than arm bands (1.5–2.5 times). The arm band-related injury probability between captures was ~ 0.2, and after 17 months half the marked animals developed injuries. Animals marked as juveniles were less likely to get injured than adults. Injuries were associated with a lower body condition in females. Body condition was positively associated with apparent survival; however, a direct effect of arm band injuries on survival estimates was not observed. The tag loss rates caused a negative bias in survival estimates. Mark-recapture studies should evaluate the efficacy of the marking technique, accounting for potential animal injury, tag loss, and bias in parameter estimation. Marking individuals should be limited to studies that monitor species with high recapture probability, using the least harmful tags possible, and balancing the burden to the animals with the potential to generate knowledge.

The study analysed the niche breadth of nesting green turtles, Chelonia mydas, on Rocas Atoll, Brazil, through stable isotopes (δ15N and δ13C), comparing samplings of egg yolk and carapace collected from two nesting groups (2017 and 2019). The mean δ15N values in egg yolk and carapace were 7.1‰ (2017) and 6.8‰ (2019), and 7.8‰ (2017) and 7.3‰ (2019), respectively. For δ13C, the mean values were -17.4‰ (2017) and -17.5‰ (2019) in egg yolk, and -18.4‰ (2017) and -17.9‰ (2019) in carapace. The results suggest herbivory in coastal-benthic environments as the main feeding pattern in this nesting population. The niche breadth was similar between 2017 and 2019 in both tissues. In general, the trophic diversity (NR, CR, CD and SEA) was comparable between years as well as the trophic redundancy (MNND and SDNND), which was overall high. The niche metrics pointed to a homogeneous feeding pattern in the two nesting groups (2017 and 2019). This study adds a piece to solve the puzzle of adult green turtle trophic ecology.