Caiman Latirostris Research Articles

Bone histology of Broad-snouted Caiman Caiman latirostris (Crocodylia: Alligatoridae) as tool for morphophysiological inferences in Crocodylia

Bone histology is an important tool for the interpretation of life patterns in animals of the past and extant fauna. The crocodylians have been studied as important inferential models for morphophysiological characteristics. We aimed to characterize the osteohistology of captive Caiman latirostris, identifying its microanatomy related to growth rates, ontogeny, and environmental conditions. We analyzed five pairs of humeri (proximal elements of the appendicular skeleton) and ribs (axial skeleton) of females’ caiman. Ribs showed, in general, woven-fibered tissues, with low vascularization and parallel-fibered bone and many resorption and erosion cavities. It presented lines of arrested growth (LAGs) in three individuals, without skeletochronological compatibility. Humeri showed a gradient of woven-fibered to parallel-fibered and lamellar-zonal bone as the individuals aging. We observed compacted coarse cancellous bone (CCCB) and a higher number of LAGs in older specimens. Ribs remodel faster than humerus, showing an intra-individual histovariability. The humeri indicated an evident growth pattern with different ontogeny stages and growth rates in different ages. Fast-growing tissues are uncommon in crocodylians, but basal metabolism and optimal growth conditions can lead to this. Bone histology of C. latirostris shows patterns that can be used as inferential models for extant and extinct groups, but we encourage further studies for a better understanding, under different environmental conditions, such as temperature and food availability.

Hematological values of wild Caiman latirostris (Daudin, 1802) in the Atlantic Rainforest in Pernambuco, Brazil

Hematological studies in crocodilians are important tools in the evolutionary diagnosis and control of sicknesses, such as anaemia, malnutrition, dehydration, inflammation, and parasitism, among others. We aimed to obtain reference intervals for the hemogram of Caiman latirostris in wild populations that inhabit Recife’s Metropolitan Region, Pernambuco. We obtained blood samples from 42 caimans, from different sexes (22 males and 20 females) and ages classes (eight hatchlings, 24 subadults and 10 adults) in two areas of Atlantic Rainforest domain. We found that hematological parameters were included within the reference intervals for other crocodilian species. It was possible to observe differences between the areas for the mean corpuscular volume values, suggesting a possible difference between adult and juvenile individuals in the two study areas. When comparing sexes, there was no significant difference between the study parameters, but it was possible to observe differences in the mean corpuscular volume, mean corpuscular hemoglobin and hemoglobin in the Estação Ecológica de Tapacurá region. Although small differences have been observed between the two populations, we can infer that the hematological parameters are similar. We can use this information to evaluate animal’s health in nature and for comparations with captive individuals, allowing the establishment of ideal maintenance conditions and assisting in the identification of possible pathologies.

Ventricular Septation and Outflow Tract Development in Crocodilians Result in Two Aortas with Bicuspid Semilunar Valves.

Background: The outflow tract of crocodilians resembles that of birds and mammals as ventricular septation is complete. The arterial anatomy, however, presents with a pulmonary trunk originating from the right ventricular cavum, and two aortas originating from either the right or left ventricular cavity. Mixing of blood in crocodilians cannot occur at the ventricular level as in other reptiles but instead takes place at the aortic root level by a shunt, the foramen of Panizza, the opening of which is guarded by two facing semilunar leaflets of both bicuspid aortic valves. Methods: Developmental stages of Alligator mississipiensis, Crocodilus niloticus and Caiman latirostris were studied histologically. Results and Conclusions: The outflow tract septation complex can be divided into two components. The aorto-pulmonary septum divides the pulmonary trunk from both aortas, whereas the interaortic septum divides the systemic from the visceral aorta. Neural crest cells are most likely involved in the formation of both components. Remodeling of the endocardial cushions and both septa results in the formation of bicuspid valves in all three arterial trunks. The foramen of Panizza originates intracardially as a channel in the septal endocardial cushion.

Sensory analysis and volatile compounds in Caiman latirostris meat in comparison with other traditional meats

PurposeThe aim of the paper is to compare consumer acceptance, sensory analysis and volatile compounds of caiman meat with regard to surubí fish and chicken meat.Design/methodology/approachCaiman tail, chicken thigh and surubí meats' cuts were cooked in a pan with little oil and salt. The affective tests of acceptance (9-points hedonic scale) and preference ranking were evaluated by 80 consumers. Sensory analysis carried out by eight trained panelists described attributes' intensities on an unstructured linear scale (0–150 mm). Volatile compounds were analysed by solid-phase micro-extraction and gas chromatography/mass spectrometry GC–MS.FindingsCaiman meat had good acceptance values of 6–7 (“like slightly” to “like moderately”), being similarly preferred to surubí but less than chicken. The ratings of bitterness, hardness, fibrous appearance, fibrous texture and cohesiveness were higher and raw colour, characteristic flavour and oiliness were lower in caiman's meat than in the others. Caiman meat had lower juiciness than chicken but similar to surubí. Caiman showed lower levels of aldehydes than chicken, lower level of hydrocarbons and higher levels of acids and esters than the other meats. Alcohols, mainly found in caiman and chicken meat, were positively associated to aroma acceptance. Hydrocarbons, mainly found in surubí meat, were positively associated with the characteristic flavour and negatively correlated with aroma acceptance. Volatile composition of meats was related to their sensory attributes and consumer acceptance.Originality/valueGiven that caiman meat showed similar acceptance and preference to that of surubí, it could be considered a good quality meat, helping promote current programmes of sustainable use of natural resources.

Biomarkers of genotoxicity, immunotoxicity and oxidative stress on Caiman latirostris (Broad-snouted caiman) hatchlings exposed to pesticide formulations and mixtures widely used in agriculture

Pesticide formulations are currently considered as one of the main factors responsible for environmental contamination worldwide. Consequently, several wild species can be affected by the over use of pesticides related to agriculture activity. The aim of this study was to evaluate genotoxicity, immunotoxicity and oxidative stress on Caiman latirostris hatchlings exposed in vivo to sub-lethal concentrations of three insecticide formulations: Endosulfan (END)-, Cypermethrin (CYP)-, and Chlorpyrifos (CPF)- based formulations, two Glyphosate (GLY)- based herbicide formulations and two different ternary complex mixtures of them.C. latirostris hatchlings, 20 days old were exposed in plastics containers with pesticide solutions (by voluntary immersion) during two months, with a progressive decrease in pesticide concentrations through time, in order to simulate their degradation in water under natural conditions.After exposure, blood samples were taken to all animals for the analysis of genotoxicity (Comet assay, Micronucleus and other nuclear abnormalities) immunotoxicity (Total and differential white blood cell counts) and oxidative stress (Lipoperoxidation and the antioxidant enzymes Catalase and Superoxide dismutase).Results indicated that the five formulations tested, as well as the complex mixtures of them, induced genotoxicity, alteration in white blood cell counts and oxidative stress at environmentally relevant concentrations. Mixtures showed different interactions depending of the biomarker analyzed.This study constitutes an integral evaluation of the effect of five pesticide formulations and two possible complex ternary mixtures widely used in soybean crops in Argentina, on different endpoints on a native reptile species, C. latirostris.

Optimizing Protocols for High-Quality RNA Extraction from Blood and Liver Tissues of the Broad-Snouted Caiman

Transcriptomic information provides fundamental insights into biological processes and can be used to determine gene expression in cell, tissue, or organism under specific physiological conditions, or in response to any environmental perturbation. Extraction of high quality RNA is a challenging step mainly in non-traditional organisms, and protocols for preservation and isolation need to be adjusted in many cases. In the present work, we aimed to develop a protocol for preservation and isolation of high-quality and quantity of RNA from blood and liver tissues of Caiman latirostris. Three preservation methods were tested: 1) flash freezing (LN2) and storage at –80°C; 2) RNAlater® conservation with progressive cooling up to –80°C); 3) preservation in TRIzol® reagent, flash freezing in LN2 and storage at –80°C. Methods 1 and 2 were tested for liver, while 2 and 3 for blood. Our results showed that both preservation methods resulted in excellent outcomes for liver samples. For blood samples however, TRIzol® preservation was an efficient procedure for adequate RNA quality, quantity, and integrity, while conservation in RNAlater® solution was inadequate in both quality and quantity for an optimal RNA extraction. Appropriate protocols were established for each tissue and are being used now for transcriptomic studies in this sentinel organism.

PARÁSITOS EN REPTILES DEL CENTRO DE CONSERVACIÓN Y REHABILITACIÓN DE ANIMALES DE VIDA SILVESTRE DE UNA UNIVERSIDAD PÚBLICA-BRASIL

The medical clinic for reptiles has grown in recent years, whether by attending free-living animals in rehabilitation centers or by acquiring them as pets. The knowledge of the parasitic fauna of the Reptilia Class is important for the identification of pathogenic agents and effective therapy. Fecal samples were collected from 35 animals of the Orders Crocodylia (N=3), Squamata (N=3) and Testudines (N=29) attended from 2013 to 2018 at the Center for Conservation and Rehabilitation of Wild Animals (PRESERVAS) of the Universidade Federal do Rio Grande do Sul (UFRGS). Fecal samples were processed by the methods of Willis, Lutz and Sheather at the Laboratory of Helminthology at UFRGS. The percentage of positive samples was 17.14% (6/35): three Trachemys dorbogni (Dumeril & Bibron 1835) presenting Serpinema spp., Physaloptera spp. and Strongyloidea, respectively; two Caiman latirostris (Daudin, 1802) with Strongyloides spp. and Augusticaecum spp., respectively, and Iguana iguana (Linnaeus, 1758) with Eimeria spp. This study expands the list of parasites in reptiles from the state of Rio Grande do Sul.

Effective population size of broad-snouted caiman (Caiman latirostris) in Brazil: A historical and spatial perspective

Caiman latirostris has a large geographic distribution, that includes Argentina, Bolivia, Brazil, Paraguay, and Uruguay. In Brazil illegal hunting and land use change have caused population decline, relatively well documented in the last three decades. Due to such circumstances, the estimate of species effective population size might help analyze its viability. Single-sample estimator was used to estimate current effective population size (Ne) of broad-snouted caiman populations in representative areas of the species range in Brazil. For the analyzes, genotypes previously obtained were used for subpopulations of the captive colony of the University of São Paulo (USP) and for wild subpopulations. The microsatellites used were Amiμ8, Amiμ11, Amiμ13, Amiμ20, Claμ2, Claμ5, Claμ6, Claμ7, Claμ8, Claμ9 and Claμ10. The 11 loci analyzed produced 18.27 alleles on average. Wild populations showed significant genic and genotypic differentiation among them (p < 0.01). Population structure analyses (Rho-statistics) at Genepop for all loci was 0.376. The effective number of population sizes (Ɵ, the Ne estimator of Migrate-n software) of Caiman latirostris populations from the captive colony at the USP was 117.1 (N = 7) for NRF, 115.2 (N = 4) for Fm1, and 107.5 (N = 4) for Fm5, on the oposite side, the mean value of theta (Ɵ) was 7.7 (N = 51) for the Atlantic SE basin wild population, 9.4 (N = 42) for the Atlantic N/NE basin wild population and 9.6 (N = 91) for the Paraná basin wild population. The mean number of migrants (M of Migrate-n software) varied from 1.7 to 1.9 estimated by migrate-n are comparable to 1.3 estimated by Genepop. It is observed that in most wild population only few adults effectively contribute to genetic variation. The following guidlines are proposed as management actions: (1) an update of population sampling; (2) redefinition, delimitation and conservation of natural habitats; and (3) new conservation genetic studies with special attention to genetic diversity recovery.

Metallic elements in aquatic herpetofauna (Crocodylia; Testudines) from a lentic Atlantic rainforest environment in northeastern Brazil.

In the present study, Fe, Cu, Cr, Cd, Pb, Ni, and Al concentrations in Caiman latirostris and Testudines blood from the Tapacurá reservoir, Pernambuco, Brazil, were investigated. Blood was acid digested with HNO3, and metals were determined by ICP-OES and FAAS. Lead showed concentrations below the established limit of detection. Eighty animals were evaluated, forty from each group. The levels of all elements were statistically significant when compared between the two studied taxa (p < 0.05). In caimans, significant differences between young and adults were observed for chromium (p = 0.0539) and aluminum (p = 0.0515). Testudines showed no statistically significant differences for the variable age structure. Gender did not influence metal concentrations detected in the present study for either group. Differences between species of testudines were significant for Fe between Mesoclemmys tuberculata vs Phrynops geoffroanus (p = 0.0932) and Kinosternon scorpioides vs Phrynops geoffroanus (p = 0.063). The inter-elementary correlations showed statistically significant differences between the elements Cr vs Al (R2 = 0.52), Cr vs Cd (0.43), Cd vs Cu (R2 = 0.41), Ni vs Cu (R2 = 0.31), Ni vs Cr (R2 = 0.30), Al vs Cd (R2 = 0.27), and Cd vs Fe (R2 = 0.26). It is concluded that blood is an excellent predictor of metals in crocodilians and testudines in the Tapacurá reservoir, with statistically significant differences when correlated to concentrations such as size and species studied. In addition, it evidenced data that prove the exposure of these animals to metals, with strong inter-elementary correlations and opening doors for future studies that seek to understand possible biological effects caused in the studied taxa.

Optimization of oil extraction from caiman fat. Characterization for use as food supplement

The leather of Caiman latirostris is highly appreciated in the fashion industry and the meat is valued as an important food but its fat are usually discarded because it has no commercial value. However it is an alternative source of essential fatty acids and could be used for human consumption. The aim was to optimize the oil extraction from Caiman latirostris fat and to carry out the chemical and microbiological characterization for its use as food supplement. The oil obtained by fusion method contains fatty acids with high nutritional quality such as oleic acid (34%), linoleic acid (30%) and α-linolenic acid (2%). The atherogenicity index was 0.29 and the thrombogenicity index 0.47. The presence of mesophilic aerobic bacteria, coliform bacteria, Escherichia coli and Salmonella were not observed, and the oil is stable for 4 months at 25 °C and for at least 8 months in an inert atmosphere at 25 °C.

Biomarkers of geno- and cytotoxicity in the native broad-snouted caiman (Caiman latirostris): Chromosomal aberrations and mitotic index

We evaluated the sensitivity of the chromosomal aberration (CA) and mitotic index (MI) assays on peripheral blood lymphocytes (PBLs) of Caiman latirostris, following ex vivo exposure to the alkylating agent, MMS. Two concentrations of MMS were tested in cultured peripheral blood. Relative to controls, MMS exposure reduced the number of metaphases observed, but both the numbers of cells with MN and the percentages of aberrant metaphases increased. The types of CA identified were chromosome and chromatid breaks, chromosomal rearrangements, monosomies, and nullisomies, with significantly higher values in the MMS-exposed groups. The incorporation of the MI and CA tests in C. latirostris can provide information on damage caused by xenobiotic exposures.

Exposure to xenoestrogens alters the expression of key morphoregulatory proteins of oviduct adenogenesis in the broad-snouted caiman (Caiman latirostris).

Endocrine disrupting compounds (EDCs) are contaminants ubiquitously found in the environment, which pose a potential threat to aquatic and wetland ecosystems. Caiman latirostris, a crocodilian species that inhabits South American wetlands, is highly sensitive to EDC exposure. Previously, we reported that early postnatal exposure to EDCs such as Bisphenol A (BPA) and 17β-Estradiol (E2) alters C. latirostris oviduct differentiation. The aim of this work was to elucidate the molecular mechanisms behind this alteration. To accomplish this, we established the ontogenic changes in histological features and the expression of Wnt-7a, Wnt-5a, β-catenin, FoxA2, desmin, and alpha smooth muscle actin (α-SMA) in the oviduct of C. latirostris. Then, we evaluated the effects of BPA and E2 exposure on these histological features and protein expressions. Our results showed that during the postnatal differentiation of the oviduct the presence of histological features related to adenogenesis is associated with the levels of expression of FoxA2, β-catenin, Wnt-5a and Wnt-7a. Early postnatal exposure to BPA and E2 decreased the presence of histological features related to adenogenesis and altered the levels of expression of FoxA2, β-catenin, Wnt-5a and Wnt-7a, as well as the desmin/α-SMA ratio. These findings suggest that altered levels of Wnt-7a, Wnt-5a, β-catenin and FoxA2 could play a role in the BPA and E2-induced alteration in oviduct differentiation in C. latirostris. Thus, impaired adenogenesis and, probably, impaired reproduction in wildlife naturally exposed to BPA and other estrogenic agonists cannot be completely ruled out.

Effects of change in temperature on the cardiac contractility of broad-snouted caiman (Caiman latirostris) during digestion.

In many reptiles, digestion has been associated with the selection of higher body temperatures, the so-called post-prandial thermophilic response. This study aimed to investigate the excitation-contraction (E-C) coupling in postprandial broad-snouted caimans (Caiman latirostris) in response to acute warming within a preferred body temperature range of crocodiles. Isometric preparations subjected to a temperature transition from 25°C to 30°C were used to investigate myocardial contractility of postprandial caimans, that is, 48 h after the animals ingested a rodent meal corresponding to 15% of body mass. The caiman heart exhibits a negative force-frequency relationship that is independent of the temperature. At 25°C, cardiac muscle was able to maintain a constant force up to 36 bpm, above which it decreased significantly, reaching minimum values at the highest frequency of 84 bpm. Moreover, E-C coupling is predominantly dependent on transsarcolemmal Ca2+ transport denoted by the lack of significant ryanodine effects on force generation. On the contrary, ventricular strips at 30°C were able to sustain the cardiac contractility at higher pacing frequencies (from 12 to 144 bpm) due to an important role of Na+ /Ca2+ exchanger in Ca2+ cycling, as indicated by the decay of the post-rest contraction, and a significant contribution of the sarcoplasmic reticulum above 72 bpm. Our results demonstrated that the myocardium of postprandial caimans exhibits a significant degree of thermal plasticity of E-C coupling during acute warming. Therefore, myocardial contractility can be maximized when postprandial broad-snouted caimans select higher body temperatures (preferred temperature zone) following feeding.

\u201cIntracascaral space\u201d an eggshell structure of Caiman latirostris eggs

In recent decades, eggshells of eggs from large-bodied reptiles have been studied by many researchers, to describe the eggshell, to compare them to extinct lineages that once inhabited our planet and also to understand how the egg provides the embryo specific conditions during incubation. In previous studies we described and characterized normal and pathologic Caiman latirostris eggshells; we also evaluated how the eggshell changes during incubation. In a study relating temperature variation and eggshell structures of successful eggs, we observed empty structures not previously described that we termed “intracascaral space”. The aim of this study is to describe this structure of C. latirostris eggshells. We hypothesize about the possible functions which it would perform during incubation and for development of the embryos.

Identification and evaluation of antioxidant and reference genes for quantitative real-time PCR in blood of Caiman latirostris

The quantitative real-time polymerase chain reaction (qPCR) has been one of the most promising approaches to perform rapid and accurate quantification of DNA in various biological systems. The aim of this study was to standardized the qPCR technique for the analysis of important genes involved in the main routes of antioxidant defense against reactive oxygen species (catalase: cat and superoxide dismutase: sod) and evaluate the stability of different reference genes in blood of Caiman latirostris hatchlings. The stability of the reference genes, β-actin, glyceraldehyde 3-phosphate dehydrogenase (gapdh) and ribosomal protein L8 (rpl8) was determined using the comparative ΔCt, NormFinder, geNorm, BestKeeper and RefFinder. Then, cat and sod genes were normalized with each reference gene and their mRNA abundances were determined through the qPCR. Stability of genes was ranked through the different methods in the following order: β-actin, rpl8 and gapdh, under normal physiological conditions. The results reveal that cat and sod genes present a similar relative mRNA abundance with β-actin and rpl8. This is the first report of the analysis of antioxidant mRNA as potential biomarkers of oxidative stress in blood for all crocodilians species. Besides, we determined the stability of different reference genes that can be used for normalization of mRNA abundance patterns in blood of C. latirostris, without the need to sacrifice the animals.

Notes on the gross anatomy of the heart of the broad-snouted caiman, Caiman latirostris (Daudin, 1802).

The broad-snouted caiman, Caiman latirostris (Daudin, 1802), is one of the six crocodilian species from Brazil. The topography, morphology and morphometry of the broad-snouted caiman heart were studied. Data were obtained from the necropsy of four adult animals, three females and one male. The hearts were removed from the coelomic cavity and fixed in 10% formalin for 48hr for morphological and morphometric description. The heart is in the cranial mediastinum. It is caudally involved by the liver cranial margins, and ventrally by the ribs, intercostal muscles, and sternum and dorsally by the lungs. The four-chambered morphology is typical with two (right and left) atria and ventricles. Right and left aortic, pulmonary and subclavian arteries branch from the truncus arteriosus. Gubernaculum cordis is present as ligamentous folds uniting the heart apex to the pericardium. Main morphometric means are the apex-to-base length (49.86mm), circumference (105.25mm) and heart weight (45.03g). The right atrium is craniocaudally longer with thicker walls, whereas the left ventricle is narrower. The topography, morphology and morphometry of the heart of C.latirostris are consistent with the anatomy of other crocodilian species.

A novel laxative method for crocodilians and digestibility of soybean (Glicine max) in broad-snouted caiman (Caiman latirostris)

The objectives of this study were to evaluate the laxative capacity of saline solution, vegetable oil, and a commercial drug on Caiman latirostris and determine digestibility of diets with plant derived protein sources as a supplement for this species. After a trial using three laxative treatments in different doses, caimans were treated with 1.5 mL of lactulose daily for two days. They were then force-fed their corresponding diet once per day for 7 days and then digesta residues were collected. Digestibility was determined through a dietary marker, acid digestion of digesta residues, and calculated with a standard equation. Digestion of diets were between 96 and 99%, exhibiting differences among these (P = 0.0006), with the control diet 2.45% lower than treatments diets (P = 0.0050). Digestibility of soybean meal was between 90 and 95%. There were differences according to the treatment diet (P = 0.018). The results of this study indicate that the use of lactulose as a laxative for C. latirostris is effective and does not affect health. Inclusion of soybean meal in the diet of C. latirostris at levels of 20–60% improved its digestibility and nutrients were efficiently digested. Deliberate ingestion of plant material by wild crocodilians may serve to aid digestion and absorption of dietary nutrients, and not act only as gastroliths. This information could be used to develop crocodilian diets and assist future research to determine optimum nutrient levels and ingredient combinations for farm-raised crocodilians fed compounded diets.

Molecular analysis and bioinformatic characterization of cooper, zinc-superoxide dismutase (Cu/Zn-sod) gene of Caiman latirostris.

Superoxide dismutase (SOD) is an antioxidant enzyme that acts as a component of first-line defense system against reactive oxygen species (ROS). Copper/Zinc superoxide dismutase (Cu/Zn-SOD) is one of the isoforms of SOD enzyme and is sensitive to the exposure of different environmental factors, in different species and tissues. Caiman latirostris is one of the two crocodilian species living in Argentina and no information is available on the molecular and biochemical characteristics of the Cu/Zn-sod gene in this species. In the present work, we reported the presence of the Cu/Zn-sod gene in C. latirostris, the nucleotide and amino acid sequences, the modelled protein structure, evolutionary distance among species and tissue specific expression patterns. Cu/Zn-sod gene was 620bp open reading frame in length and encoded 178 amino acids. The nucleotide sequences of C. latirostris shared high similarity with the Cu/Zn-sod genes of other crocodilian species, so it showed to be highly conserved. PCR analysis showed that Cu/Zn-sod gene was expressed in all the tissues examined (liver, gonads, spleen, heart, and whole blood), suggesting a constitutively expressed gene in these tissues. This study allows further investigation into the structure-activity relationship and the mechanism of action of Cu/Zn-SOD, besides exploring the functional breadth and possible alteration factors, including xenobiotics.

Sexual Identification of Caiman latirostris Hatchlings by Cloacal Inspection

Sexual identification of crocodilians is important in population studies and provides useful information for conservation and management plans and monitoring populations over time. It is possible to distinguish between male and female Caiman latirostris by cloacal palpation or eversion of the penis in individuals larger than 75 cm total length, but smaller animals possess a barely differentiable cliteropenis. In hatchlings, sex determination methods involve surgical examination, necropsy, or analysis of cranial dimorphism, which cannot be applied in the field. We classified hatchlings of C. latirostris by observing the color and shape of their genitals. The penis is a milky white organ with a rounded shape at the tip and a purple hue at the end, whereas the clitoris is shorter, whitish, and has a pointed end. The procedure was tested on hatchlings from three nests at the “Proyecto Yacare” study area (Santa Fe province); half of the eggs of each nest were incubated at a constant temperature of 31°C (producing females) and the other half at 33°C (producing males). To observe the sexual organs by cloacal inspection, we used a modified instrument whose function during palpation is like that of a finger applied in large animals to evert the penis or clitoris. In the first days after hatching we correctly scored the sex of 80% of the individuals. The number of correct identifications was slightly lower for males than for females. This technique might be a useful tool for field studies, as it allows the sex of small caimans to be estimated in situ.

Growth Curves of Wild and Reintroduced Broad-Snouted Caimans (Caiman latirostris) and Their Management Implications

We describe body growth functions of broad-snouted caimans (Caiman latirostris) for wild and reintroduced individuals. Snout–vent length (SVL, cm) and age of young individuals and adult females were recorded for two different groups: (Py) animals born in the Proyecto Yacare ranching program, from eggs collected in the wild; and (Wy) wild caimans Class I (< 25 cm SVL) whose age was determined by Size Frequency Analysis, plus females reintroduced by the Proyecto Yacare and subsequently recaptured at reproductive age. To describe body growth, we adjusted five models through non-linear regression: Logistic, 4-Parameter Logistic (4-PL), Gompertz, 4-Parameter Gompertz (4-G), and von Bertalanffy. Each group was analyzed separately (Py and Wy), and we selected the most parsimonious model based on the Akaike criterion. We also analyzed the possible linear growth difference using ANCOVA. For Py, the Logistic model was best, whereas for Wy the most suitable was 4-PL, in which wild animals would arrive at the inflexion point 1.4 years later on average than in Py. Analyzing the stage at which their development was linear in shape, we detected that the wild animals had a similar growth rate to reintroduced individuals. As a result, although Py animals had experienced accelerated development whilst in captivity, it did not modify their subsequent growth in the wild. The likelihood of survival in this species increases with body size, thus it is important to emphasize that reintroduced animals are larger than wild animals of the same age and that previous farming conditions seem not to affect their growth in the wild. Therefore, we expect that reintroduced caimans will exhibit greater survivorship than natural animals of the same age. Consequently, an adjustment of the current ranching program should be considered, in the sense that population viability could be achieved by reintroducing a lower number of caimans each season.