Tupinambis Merianae Research Articles

Classification of sex-dependent specific behaviours by tri-axial acceleration in the tegu lizard Salvator merianae

Validated patterns of behaviour detected by tri-axial acceleration in the laboratory can be used for remote measurements of free-living animals. The tegu lizard naturally occupies diverse biomes in South America and presents ecological threats in regions where it was artificially introduced. We aimed to validate the use of tri-axial acceleration to distinguish among behaviours of male and female tegus in captivity by comparing observed behaviours to recorded acceleration data. Adult animals were externally fitted with an accelerometer fixed between their scapulae to quantify anteroposterior, lateral, and dorsoventral acceleration. Video recordings of cameras positioned on the walls of the animal-holding arena documented behaviours. Behaviour patterns, such as resting, walking, and eating, were identified for both sexes, and nest building in females and courtship and copulation in males. Random Forest algorithm was used to validate the behaviour patterns from accelerometry data based on two models, random split (70 % training-30 % validation; RS) and leave-one-out (divided by individual; LOO). Although LOO showed lower accuracies than RS for all the acceleration data, nest building in females and copulation in males had high accuracies in both models. In contrast, the lowest accuracies for walking and eating indicates they may involve more inconsistent movement patterns. Comparing the results from RS and LOO, female behaviours may be more identifiable in the field using triaxial accelerometry than males. The identification of behaviours by accelerometry, especially related to reproduction, without the necessity for direct observation of the tegus would be helpful for conservation purposes, for both natural and invasive populations.

A mystery revealed: an update on eosinophil and other blood cell morphology of the Argentine black and white tegu (Salvator merianae)

A mystery revealed: an update on eosinophil and other blood cell morphology of the Argentine black and white tegu (Salvator merianae)

Mitochondrial function in skeletal muscle contributes to reproductive endothermy in tegu lizards (Salvator merianae).

In cyclic climate variations, including seasonal changes, many animals regulate their energy demands to overcome critical transitory moments, restricting their high-demand activities to phases of resource abundance, enabling rapid growth and reproduction. Tegu lizards (Salvator merianae) are ectotherms with a robust annual cycle, being active during summer, hibernating during winter, and presenting a remarkable endothermy during reproduction in spring. Here, we evaluated whether changes in mitochondrial respiratory physiology in skeletal muscle could serve as a mechanism for the increased thermogenesis observed during the tegu's reproductive endothermy. We performed high-resolution respirometry and calorimetry in permeabilized red and white muscle fibers, sampled during summer (activity) and spring (high activity and reproduction), in association with citrate synthase measurements. During spring, the muscle fibers exhibited increased oxidative phosphorylation. They also enhanced uncoupled respiration and heat production via adenine nucleotide translocase (ANT), but not via uncoupling proteins (UCP). Citrate synthase activity was higher during the spring, suggesting greater mitochondrial density compared to the summer. These findings were consistent across both sexes and muscle types (red and white). The current results highlight potential cellular thermogenic mechanisms in an ectothermic reptile that contribute to transient endothermy. Our study indicates that the unique feature of transitioning to endothermy through nonshivering thermogenesis during the reproductive phase may be facilitated by higher mitochondrial density, function, and uncoupling within the skeletal muscle. This knowledge contributes significant elements to the broader picture of models for the evolution of endothermy, particularly in relation to the enhancement of aerobic capacity.

Licuri (<i>Syagrus coronata</i>) consumption by <i>Salvator merianae</i> in the Caatinga seasonally dry forest: nutritional and ecological implications

Licuri (<i>Syagrus coronata</i>) consumption by <i>Salvator merianae</i> in the Caatinga seasonally dry forest: nutritional and ecological implications

The influence of the post-hepatic septum and abdominal volume on breathing mechanics in the lizard Salvator merianae (Squamata: Teiidae).

Teiid lizards possess an incomplete post-hepatic septum (PHS) separating the lungs and liver from the remaining viscera, and within this group, Salvator merianae has the most complete PHS. In this study, we explored the combined effects of the presence of the PHS and alterations in abdominal volume on the mechanics of the respiratory system. The PHS is believed to act as a mechanical barrier, mitigating the impact of the viscera on the lungs. Using established protocols, we determined static (Cstat) and dynamic (Cdyn) compliance, lung volume and work of breathing for the respiratory system in tegu lizards with intact (PHS+) or removed (PHS-) PHS, combined with (balloon+) or without (balloon-) increased abdominal volume. The removal of the PHS significantly reduced resting lung volume and Cdyn, as well as significantly increasing the work of breathing. An increase in abdominal volume significantly reduced Cstat, Cdyn, and resting and maximum lung volume. However, the work of breathing increased less in the PHS+/balloon+ treatment than in the PHS- treatments. These results highlight the barrier function of the PHS within the tegu lizard's body cavity. The septum effectively reduces the impact of the viscera on the respiratory system, enabling the lungs to be ventilated at a low work level, even when abdominal volume is increased. The presence of the PHS in teiid lizards underscores how extrapulmonary structures, such as septal divisions of the body cavity, can profoundly affect pulmonary breathing mechanics.

When to target control efforts? Using novel GPS telemetry to quantify drivers of invasive Argentine black and white tegu (Salvator merianae) movement

When to target control efforts? Using novel GPS telemetry to quantify drivers of invasive Argentine black and white tegu (Salvator merianae) movement

Pesticides compromise health: a comparison between lizards collected within and outside an agricultural area.

Reptiles are the least studied vertebrates regarding the impact of pesticides on their health, despite being good models for ecotoxicological studies given their abundance and easy handling. Salvator merianae is widely distributed in South America and often found in agricultural cultivation areas. Here, we compared the morphological, biochemical, and physiological parameters of S. merianae from an exposed area (EA) to pesticides and a reference area (RA) or control. These parameters were measured in plasma (albumin, alanine transaminase, alkaline phosphatase, gamma-glutamyl transpeptidase, glucose, total proteins, uric acid, triglycerides, VLDL, and corticosterone) and in erythrocytes (TBARS, glutathione S-transferase, superoxide dismutase, and catalase activity). Blood samples were collected from 28 lizards (EA: three juveniles, three adult females, and three adult males; RA: nine juveniles, four females, and five males) in southern Brazil during the reproductive period. We observed a decrease in body mass, the ratio between body mass and total length and snout-vent length in juvenile lizards collected at EA. The levels of TBARS, glutathione S-transferase, triglycerides, VLDL, and uric acid were altered for juveniles in EA. When comparing the two areas, females differed in superoxide dismutase activity and total proteins, while males differed in superoxide dismutase, catalase, and glutathione S-transferase activity. This set of results shows that S. merianae, especially juveniles, suffers a negative impact when inserted in an agricultural area. The analyzed biomarkers proved suitable for monitoring these lizards and the quality of this environment.

The impact of RS–040 highway on wildlife roadkill patterns, Porto Alegre, Southern Brazil.

Road infrastructure has caused severe impacts on the environment and wildlife. Understanding and mitigating these effects are essential conservation measures. This study aimed to evaluate wildlife mortality due to animal-vehicle collisions along an 80-km stretch of the Tapir Rocha Highway (RS–040). The field inventory was carried out between August 2015 and March 2019. Once a week, two observers drove along the highway at an average speed of 40 km/h and all the vertebrate roadkill spotted from the car were assessed to record the species, carcass condition, and the roadkill locations along the road. In total, 2,371 dead animals were recorded and categorized into 137 species. The most affected classes were mammals (n = 1,223), and birds (n = 704). The most affected wild species were white-eared opossums (Didelphis albiventris, n = 559), black-and-white tegus (Salvator merianae, n = 129), and coypus (Myocastor coypus, n = 102). Carcass exposure assessments indicated that many (n = 637) of the animal deaths occurred the night before our arrival, which may suggest that nocturnal species were among the most vulnerable to mortality. Roadkill sighting peaked in the spring (34%) and summer (25%), probably due to reproductive activity and juvenile dispersal. Evident seasonal variations included a 50% reduction in reptile roadkill rates in autumn-winter compared to spring-summer, and a 20-percentage-point increase in the number of mammal road deaths in the winter. The reduced activity that reptiles display at low temperatures, and seasonal changes in carnivore food habits may explain these respective findings. While most of the animal victims of roadkill were common and widely distributed species with abundant populations, decreasing abundance of these species is a growing conservation concern.

First report of melanophoroma in Salvator merianae

Cutaneous neoplasms have been described in the class Reptilia, and many of them are related to the inadequate management of these animals in captivity. In Brazil, there are few reports of cutaneous neoplasms in Iguana iguana, but no reported cases in Salvator merianae. Therefore, the objective of this work was to report a case of a melanophoroma diagnosed in a Salvator merianae. A tegu with a skin nodule located in the dorsal region, close to the right scapula, measuring 1 cm, in diameter, blackish, elevated, firm in consistency, well defined, non-ulcerated and non-adherent, was surgically removed and sent to histopathology analysis, witch revel melanophoroma. The animal in this report had a follow up for eight months after the procedure, and was discharged without signs of other skin nodules. The present report seeks to add to the literature on reptile medicine by describing a histopathological diagnosis of melanophoroma in Salvator merianae, in addition to the clinical-surgical treatment and its respective clinical follow-up.

Successful emergency surgery for accidental ingestion of multiple neodymium magnets in an Argentine tegu (Salvator merianae).

A large Argentine tegu (Salvator merianae) presented with anorexia. Initial radiographs revealed a metallic foreign body in the stomach. The tegu vomited and became inactive two days later. A follow-up radiograph revealed the persistence of the foreign body in the same region. The foreign body was identified as a cluster of multiple magnets resembling neodymium magnets reported missing by the owner. An emergent laparotomy was performed due to gastrointestinal perforations caused by the multiple magnets. The surgical intervention revealed perforations in the walls of the stomach and small intestine and progressing acute peritonitis. Three magnets were extracted from the abdominal cavity and the tegu showed recovery. At 200 days postoperatively, the tegu continued to demonstrate good appetite and energy levels.

Oxidative and osmotolerant effects in Salvator merianae (Squamata: Teiidae) red blood cells during hibernation.

Hibernation is a natural condition of animals that lives in the temperate zone, although some tropical lizards also experience hibernation annually, such as the lizard native from South America, Salvator merianae, or "tegu" lizard. Even though physiological and metabolic characteristic associated with hibernation have been extensively studied, possible alterations in the red blood cells (RBC) integrity during this period remains unclear. Dehydration and fasting are natural consequences of hibernating for several months and it could be related to some cellular modifications. In this study, we investigated if the osmotic tolerance of RBCs of tegu lizard under hibernation is different from the cells obtained from animals while normal activity. Additionally, we indirectly investigated if the RBCs membrane of hibernating tegus could be associated with oxidation by quantifying oxidized biomolecules and the activity of antioxidant enzymes. Our findings suggest that RBCs are more fragile during the hibernation period, although we did not find evidence of an oxidative stress scenario associated with the accentuated fragility. Even though we did not exclude the possibility of oxidative damage during hibernation, we suggested that an increased RBCs volume as a consequence of hypoosmotic blood during hibernation could also affect RBCs integrity as noted.

Anfíbios e répteis do Refúgio Biológico Bela Vista – hidrelétrica Itaipu, estado do Paraná, sul do Brasil

Abstract Information regarding species occurrence is fundamental to understanding biodiversity distribution. However, the biodiversity from the west of the state of Paraná has been historically less studied, especially amphibians and reptiles. For this reason, we present the first reptile list of species from the west of the state of Paraná and extend the current list of anurans for the municipality of Foz do Iguaçu. The species list was based on a systematic field study conducted at Refúgio Biológico Bela Vista (RBV) a conservation area within the Hydroelectric Power Itaipu Binacional. We integrated the species list with previous species observations available in the literature for the same place where our sampling was conducted. A total of 41 species of amphibians and reptiles are presented. All amphibians species found were recorded in the field; however, from the 22 species of reptiles recorded, three were historical records obtained before this study. Species were all classified as Least Concern and/or had stable populational status according to the IUCN. Sampling sufficiency was achieved for anurans but not for reptiles, probably due to low abundance of several snake species. The most abundant species of anuran was Dendropsophus nanus, from the Hylidae family, whereas Leptodactylus plaumanni and Scinax squalirostris were represented by only one individual each. The lizard Salvator merianae was the most abundant reptile, and seven species were represented by only one individual each. The most successful sampling method for adult anurans was active search in water bodies whereas most of reptile species were observed by accidental encounters and not through a systematic sampling method. We found that herpetofauna composition from RBV was similar to other communities from Paraná state that also occur within the Semideciduous Seasonal Forest. Finally, as additional information to the species list, we offer species identification keys and discuss the importance of Refúgio Biológico Bela Vista to harbor the anuran and reptile diversity of the region.

INFECTIOUS STOMATITIS IN CAPTIVE SALVATOR MERIANAE LIZARDS

Infectious stomatitis is a common ailment in captive reptiles, it arises from a combination of predisposing factors such as poor nutritional conditions, habitat issues or stress, where normal oral flora microorganisms act as pathogens, facilitating the disease development. This study aims to describe infectious stomatitis in a captive population of adult Salvator merianae lizards and to propose prophylactic measures for their maintenance in captivity. Within a population of 57 animals, a morbidity rate of 19.2% and a mortality rate of 7% were estimated. Microbiological analysis of oral mucosa revealed Pseudomonas aeruginosa susceptible to ceftazidime, ciprofloxacin, gentamicin, and amikacin. Symptoms ranged from asymptomatic to animals with mild oral cavity lesions or severe stomatitis, with some cases exhibiting respiratory complications. Histopathological examination of lung samples was consistent with caseous pneumonia. Intramuscular ceftazidime treatment and oral disinfection yielded excellent results for lizards with stomatitis, although a favorable response was not observed in animals with pneumonia.

Skin lipids alone enable conspecific tracking in an invasive reptile, the Argentine black and white tegu lizard (Salvator merianae).

Locating potential mates in non-native habitats is one of the most important challenges faced by invasive vertebrate species. The Argentine black and white tegu lizard (Salvator merianae) is a major invasive reptile species in the contiguous United States and is rapidly expanding its range across Florida and the Southeast, in part due to inadequate management strategies and tools. Because a wide array of reptiles, especially squamates (snakes and lizards), have been well-studied for their reliance on chemical cues to locate conspecifics, our project aimed to isolate chemical cues from tegus and assess the ability of adult males and females to use only these cues to make navigation decisions within a Y-maze. Previously, we found that both males and females can follow conspecific scent trails, but the nature of the specific cues used by the tegus was unknown. In this study, we extracted skin lipids from male and female shed skins acquired during the breeding season then tested the extracts for bioactivity at different dilutions prior to Y-maze trials. Both sexes showed positive reactions (e.g., tongue-flicking, nose taps, scratching) to 2:1 skin lipid:hexane dilutions. In the Y-maze, males (n = 7) and females (n = 7) were run in three types of trailing scenarios with these skin lipid extracts: Male-only (pooled lipid extracts from male shed skins), Female-only (extracts from female shed skins), and Male vs. female. Regardless of the tegu lipid type present, tegus preferred to follow the conspecific lipid trail when paired with a neutral control (peanut oil; 2:1 dilution). They also preferred opposite-sex skin lipid trails when paired with same-sex skin lipid trails. We analyzed our results further by comparing them to those of Richard, Bukovich, et al. (2020). We found a synchronization effect of the skin lipids: sex differences in behavior detectable in the scent trail trials were absent when only conspecific skin lipids were present in the environment. Our results indicate that skin lipids alone are sufficient to facilitate mate tracking in S. merianae, these chemical cues induce reliable behavior, and extracted skin lipids have potential for modifying movement patterns of an invasive reptile in their non-native range. If leveraged in concert with current tegu management strategies (i.e., trapping), extracted skin lipids have the potential to bolster management efficacy but field trials are a requisite next step.

The yellow armadillo as a potential predator of medium-sized vertebrates

Studies on the predation of vertebrates by armadillos are scarce, and most of them refer to the consumption of small reptiles and rodents, attributing the remains of larger prey to the ingestion of carrion. However, there is evidence that some species of the Chlamyphoridae family may have predatory habits, killing and consuming even larger prey. In this study, we document predation of a black-and-white tegu (Salvator merianae) and a gray brocket deer (Mazama gouazoubira) by a yellow armadillo (Euphractus sexcinctus) in the northeast of Argentina, and we review attacks and captures of other medium- to large-sized vertebrates by this armadillo. The results suggest that the yellow armadillo could play a hitherto underestimated role in the food webs of the communities of which they are a part.

Immuno-endocrine alterations and oxidative stress induced by commercial formulations of pesticides in the tegu lizard (Salvator merianae)

Recent research has shown the risk of environmental contamination by pesticides in Argentina. Salvator merianae is considered as “sentinel species” for monitoring their effects. We intended to investigate growth, immunological and endocrine functions, and oxidative stress in S. merianae exposed to two commercial brands of the herbicide glyphosate: Roundup and Panzer Gold, as well as, to two insecticides: chlorpyrifos, and cypermethrin. Our results showed a higher increase in growth in animals exposed to Roundup and chlorpyrifos and a lower increase in those exposed to Panzer Gold. Higher total leukocyte and lymphocyte count values were observed in lizards exposed to Panzer Gold. The heterophils/lymphocytes ratio decreased in all treated animals. Regarding lobularity index, natural antibodies titers, and complement system activity values, lizards exposed to cypermethrin had higher values. Low corticosterone levels were observed in animals exposed to Roundup. Our results reveal different toxic effects of pesticides contributing to the knowledge of the pesticides’ potential deleterious impact in the habitat of S. merianae.

Capsaicin-treated bait is ineffective in deterring non-target mammals from trap disturbance during invasive lizard control

Excluding non-target species from invasive species control efforts can be challenging due to non-target attraction to trap structure, baits, and lures. Various methods have been used to deter non-target species from entering or disturbing traps including altered features (e.g., mesh size, trip mechanism, or entrances), staking traps, and chemical deterrents. Invasive populations of Argentine Black and White Tegu lizards (Salvator merianae) occur in several locations across Florida and Georgia, and there are ongoing trapping efforts to control them. At sites in Georgia, non-target mammals disturb most of the lizard traps (>80%), consume egg bait/lures, and thus reduce trap efficacy. In contrast, our Florida site has fewer problems with non-target mammals. Our goal was to quantify the efficacy of capsaicin-coated eggs, a known distasteful irritant to mammals, as a non-target bait deterrent in live traps set for tegus in both Georgia and Florida. We conducted feeding assays on three tegus and found that individuals readily consumed food coated in capsaicin. We then conducted a three-part, live trapping experiment to test 1) if trap disturbance by mammals habituated to eggs without capsaicin decreased when capsaicin-coated eggs were deployed in Georgia, 2) if mammals not habituated to eggs as bait (treated or untreated) disturbed live traps at the same rate as those habituated to eggs in Georgia, and 3) if tegu capture rates were different when capsaicin treated eggs were deployed in Florida. In Georgia, we found that trap disturbance by non-target mammals did not decrease when capsaicin was applied to eggs in an area previously habituated to trapping with this bait nor when applied in a novel area. In Florida, we found no significant difference in tegu captures using capsaicin-treated vs. untreated bait. Tegus were tolerant of capsaicin, but capsaicin treated eggs did not reduce non-target mammal disturbance to traps. Therefore, removal of invasive populations could be problematic if methods to reduce trap disturbance by non-targets are not identified and deployed.

Testicular abnormalities in the invasive Argentine Black-and-White Tegu (Salvator merianae) in the Florida Everglades

Testicular abnormalities in the invasive Argentine Black-and-White Tegu (Salvator merianae) in the Florida Everglades

How to estimate body condition in large lizards? Argentine black and white tegu (Salvator merianae, Duméril and Bibron, 1839) as a case study.

Body condition is a measure of the health and fitness of an organism represented by available energy stores, typically fat. Direct measurements of fat are difficult to obtain non-invasively, thus body condition is usually estimated by calculating body condition indices (BCIs) using mass and length. The utility of BCIs is contingent on the relationship of BCIs and fat, thereby validation studies should be performed to select the best performing BCI before application in ecological investigations. We evaluated 11 BCIs in 883 Argentine black and white tegus (Salvator merianae) removed from their non-native range in South Florida, United States. Because the length-mass relationship in tegus is allometric, a segmented linear regression model was fit to the relationship between mass and length to define size classes. We evaluated percent, residual, and scaled fat and determined percent fat was the best measure of fat, because it was the least-associated with snout-vent length (SVL). We evaluated performance of BCIs with the full dataset and within size classes and identified Fulton's K as the best performing BCI for our sampled population, explaining up to 19% of the variation in fat content. Overall, we found that BCIs: 1) maintained relatively weak relationships with measures of fat and 2) splitting data into size classes reduced the strength of the relationship (i.e., bias) between percent fat and SVL but did not improve the performance of BCIs. We postulate that the weak performance of BCIs in our dataset was likely due to the weak association of fat with SVL, the body plan and life-history traits of tegus, and potentially inadequate accounting of available energy resources. We caution against assuming that BCIs are strong indicators of body condition across species and suggest that validation studies be implemented, or that alternative or complimentary measures of health or fitness should be considered.

Morphological and physiological traits of the respiratory system in Iguana iguana and other non-avian reptiles

Functional morphology considers form and function to be intrinsically related. To understand organismal functions, a detailed knowledge of morphological and physiological traits is necessary. Regarding the respiratory system, the combined knowledge about pulmonary morphology and respiratory physiology is fundamental to understand how animals exchange gases and regulate critical functions to sustain metabolic activity. In the present study, the paucicameral lungs of Iguana iguana were analyzed morphometrically through stereological analysis using light and transmission electron images and compared with unicameral and multicameral lungs of six other non-avian reptiles. The morphological data were combined with physiological information to perform a principal component analysis (PCA) and phylogenetic tests of the relationship of the respiratory system. Iguana iguana, Lacerta viridis, and Salvator merianae presented similar pulmonary morphologies and physiologies when compared to Varanus examthematicus, Gekko gecko, Trachemys scripta, and Crocodylus niloticus. The former species showed an elevated respiratory surface area (%AR), a high diffusion capacity, a low volume of total parenchyma (VP), a low percentage of parenchyma concerning the lung volume (VL), and a higher surface/volume ratio of the parenchyma (SAR/VP), with high respiratory frequency (fR) and consequently total ventilation. The total parenchymal surface area (SA), effective parenchymal surface-to-volume ratio (SAR/VP), respiratory surface area (SAR), and anatomical diffusion factor (ADF) showed a phylogenetic signal, evidence that the morphological traits are more strongly correlated with the species' phylogeny than the physiological traits. In sum, our results indicated that the pulmonary morphology is intrinsically related to physiological traits of the respiratory system. Furthermore, phylogenetic signal tests also indicate that morphological traits are more likely to be evolutionary conserved than physiological traits, suggesting that evolutive physiological adaptations in the respiratory system could happen faster than morphological changes.