Competition can generate different ecomorphological patterns resulting in trade-offs, considering that certain resources are better used than others. We investigated how three species of Boana share resources in Serra de Itabaiana National Park and how morphology and environment cause trade-offs in interactions. We hypothesized that the large body size of B. faber might favor coexistence, allowing niche segregation with the other, smaller species B. albomarginata and B. pombali. Data collection occurred in the dry season of 2019 through active search at 18:00–22:00. We obtained microhabitat data for the species, recorded morphometric measurements, and analyzed gastrointestinal contents. There is evidence of resource partitioning in vertical space, as the large species occurs at ground level while the smaller congeners are found on higher perches. We hypothesize that lower sites can better support the large B. faber at our study site. There are no differences in the trophic niche, as prey volumes did not differ among the three species. Nevertheless, the size factor rendered low niche overlaps between B. faber and B. albomarginata, which are the phylogenetically closest species. Moreover, the species consumed typical prey of certain height ranges and accessed different items with high energy or hydric value. We believe that the sampling period performed in the dry season provides important trade-offs between the species studied with body size and ecological factors being crucial in this.

Studies on crocodilians indicate that energy investment in reproduction is conditioned by prey availability, which is in turn affected by rainfall. Therefore, environmental variables may affect individual body condition (BC) and physiological condition (PC). We evaluated the influence of climatic factors on the BC and PC of wild reproductive female Caiman latirostris and their performance in different seasons. We found no relationship between female BC and climatic variables, which indicates that only females that have managed to overcome a minimum required BC can reproduce and suggests that the minimum BC is not fixed. Females with higher BC produced nests with greater hatching success, proving that if there is a minimum energy threshold that triggers reproduction; once the threshold is surpassed the excess energy may be invested in quality of progeny. We observed that as rainfall increases in river headwaters in March–April, clutch size decreases, indicating that in years with lower rainfall, only larger females may reproduce. Regarding PC, muscle fatty acid (FA) indicated C18:2 has a strong association with minimum temperatures in September, suggesting that temperatures of the first warm months determine the availability of food. Also, variation in plasma FA are associated with precipitation in October and December, showing that precipitation influences diet and PC. We conclude that rainfall and minimum ambient temperatures modulate the reproduction of C. latirostris and the dynamics of the population as a whole. Also, BC is a useful indicator for evaluating reproductive performance and PC is a useful indicator to evaluate nutritional status of populations.

Estudios en cocodrilianos indican que la energía invertida en reproducción es condicionada por la disponibilidad de presas, el que a su vez es afectado por las precipitaciones. Por lo tanto, variables ambientales podrían afectar la condición corporal (CC) y condición fisiológica (CF) de los individuos. Evaluamos la influencia de los factores climáticos en CC y CF en la reproducción de hembras silvestres de Caiman latirostris y su performance en diferentes temporadas. No encontramos relación entre la CC de las hembras y variables climáticas, lo que indica que solo las hembras que alcanzan una CC mínima requerida se reproducirán; lo que sugiere que esta CC mínimo no es fijo. Las hembras con mayor CC produjeron nidos con mayor éxito de eclosión, lo que demuestra que si hay un umbral mínimo de energía que desencadena la reproducción, una vez superado el umbral el exceso de energía puede invertirse en la calidad de la progenie. Observamos que, a medida que aumentan las precipitaciones en las cabeceras de los ríos durante marzo–abril, disminuye el tamaño de las puestas, lo que indica que en los años con menos precipitaciones sólo se reproducen las hembras de mayor tamaño. En cuanto a la CF, el ácido graso (AG) muscular C18:2 tiene una fuerte asociación con las temperaturas mínimas en septiembre, lo que sugiere que las temperaturas de los primeros meses cálidos determinan la disponibilidad de alimento. Además, la variación de los perfiles de AG plasmáticos está asociada a las precipitaciones en octubre y diciembre, lo que demuestra que las precipitaciones influyen en la dieta y la CF. Concluimos que las precipitaciones y las temperaturas mínimas ambientales modulan la reproducción de C. latirostris y la dinámica de la población en su conjunto. Además, la CC es un indicador útil para evaluar el rendimiento reproductivo y la CF es un indicador útil para evaluar el estado nutricional de las poblaciones.

In amphibians, the presence in the fertilization medium of diffusible components from the jelly coat, called diffusible factors, is indispensable. However, few studies of anuran species have characterized the biomolecule capable of inducing the acrosome reaction. Our previous studies of a species of anuran amphibian (Rhinella arenarum) from the Andean Yungas of northwestern Argentina demonstrated that uterine oocytes that contain the jelly coat lose fertilizability in the insemination medium depending on washing time and washing medium. Such loss can be reversed by the addition of all the proteins and glycoproteins from the diffusible factor (DF), an effect that reaches a maximum with the addition of exogenous Ca²⁺. In the present study, we employed an experimental model to demonstrate the biological effect of DF and of four purified protein fractions from DF on conditioning coelomic oocytes. Our experiments demonstrated that only purified fraction 2 of DF, which contains only a 74 KDa diffusible glycoprotein (gp74), caused characteristic modifications on the surface of the conditioned coelomic oocytes, identical to the ones generated by the acrosomal lysine solution. These modifications of the oocytes did not occur in the absence of sperm in the medium. Furthermore, previous treatment of a sperm suspension with gp74 and later incubation of the supernatant obtained from this pretreatment with the conditioned coelomic oocytes caused the same lytic effect on the oocyte surface, confirming that gp74 participates by inducing the release of the acrosomal content in the insemination medium. These results are a new contribution to the knowledge on the fertilization of this anuran species and allow us to continue with the study of the gp74 receptor in the spermatozoon.

Marking methods that do not affect survival are crucial to study anuran demography. Toe-clipping is among the most frequent marking methods in anurans. Nonetheless, the potential effect of toe-clipping on locomotion—and consequently on survival—is controversial. We studied a free-ranging population of Iberian green frogs (Pelophylax perezi) to test whether toe-clipping reduces jumping distance. Also, we compared return rates of frogs identified by toe-clipping and tagging with passive integrated transponders (PITs) after 1 year. We found no effect of toe-clipping on jumping distance, which minimizes the likelihood of toe-clipping diminishing return rates. Accordingly, we detected similar return rates in frogs marked by toe-clipping and PIT-tagging. Both techniques proved similarly efficient, although toe-clipping is cheaper and faster than PIT-tagging.

Para estudiar la demografía de los anuros, son cruciales métodos de marcaje que no afecten a la supervivencia. El corte de dedos está entre los métodos de marcaje más frecuentes en los anuros. Sin embargo, el efecto potencial del corte de dedos sobre la locomoción—y, en consecuencia, sobre la supervivencia—es controvertido. En este trabajo, estudiamos una población silvestre de rana verde común (Pelophylax perezi) para testar si el corte de dedos reduce la distancia de salto. Al cabo de un año, también comparamos las tasas de retorno—y, por ende, la supervivencia—de ranas sometidas a corte de dedos o a marcaje por PIT. No encontramos efecto del corte de dedos en la distancia de salto de estas ranas, lo que minimiza la posibilidad de que el corte de dedos afecte a las tasas de retorno. En consonancia, detectamos tasas de retorno similares en ranas marcadas por corte de dedos y por PIT. Ambas técnicas demostraron una eficiencia similar, aunque el corte de dedos es más barato y rápido que el marcaje por PIT.

Tadpoles display a wide variation in both ecology and morphology. Their ecomorphological variation can be characterized by classification schemes based on specific traits or quantifying traits representing ecological differences. Here, we describe the ecomorphospace of tadpoles inhabiting Atlantic Forest streams and compare it to a widely used ecomorphological guild classification scheme. Ecomorphological traits were quantified from linear measurements of the larval body plan, oral disc position, and flagella presence. We recorded 19 tadpole species classified into seven ecomorphological guilds. Nektonic and neustonic species were clear-cut segregated from the remaining guilds. Nonetheless, the benthic-nektonic axis of ecomorphological variation harbors an intermediary guild between the nektonic and the benthic species. A clustering approach failed to retrieve the ecomorphological guilds primarily by not discerning differences among benthic specialized guilds. Hence, despite the common application of ecomorphological traits to characterize tadpole functional diversity, it seems that alternative traits are necessary to achieve such a goal.

The vocalizations of many species of frogs in the megadiverse genus Pristimantis are unknown. Among those species lacking details is Pristimantis pardalis (leopard robber frog). Our objective was to describe the advertisement call of this species based on populations from Costa Rica and Panama. We obtained digital audio recordings of 235 vocalizations from 10 frogs and analyzed them using the software packages Raven Pro and Seewave for program R. First, we evaluated the effects of reverberation on the fine-scale temporal properties of P. pardalis vocalizations. We found that reverberation artificially inflated note duration 4–13 times; consequently, we limited our selection of each call to include only the initial burst of sound energy during temporal analysis. We found P. pardalis calls consist of 1–5 short, high-energy notes producing a “tik” sound. The notes have a mean duration of 0.006 (± 0.002) seconds and a mean dominant frequency of 2.56 (± 0.13) kHz. Qualitatively, their vocalizations are very similar to those of the closely related P. altae. Note durations and dominant frequencies from the population of P. pardalis in Panama were more similar to those of P. altae than to those of the P. pardalis population from Costa Rica. Further work should be done to assess the taxonomic status of these populations. Our results will facilitate field identification and contribute to future integrative taxonomic efforts.

We analyzed the spatial distribution of the narrow-range and threatened reptiles from the Pampas grassland, a region with high human influence in east-central Argentina. We used field-collected and museum specimens combined with high-resolution environmental variables to recognize common distributional patterns and the variables that best explain them, estimate the suitable habitat for each species, identify conservation priority areas, and finally propose management and conservation priorities related to the current protected areas. Distribution models diverged into two distributional patterns for the narrow-range species: suitable habitat for most species in highland grasslands of the montane environment, and suitable habitat for Liolaemus multimaculatus in the grassland of the coastal dunes. Growing degree-days was the most informative environmental variable for constructing the distribution models, followed by annual potential evapotranspiration, and temperature seasonality. We proposed priority areas on the basis of two different conservation algorithms: the additive benefit function, which favors the montane and sandy environments, prioritizing areas with high richness of narrow-range species, and the core-area zonation, which prioritizes the occurrence of all biodiversity features, further indicating fragmented areas in the surroundings with low human influence index, but lacking the studied species. Regardless of the algorithm used, our results showed that the existing protected areas in the region are inadequate to protect the narrow-range reptiles. Protecting at least 5% of the priority areas with higher conservation values and considering the cost of the human influence index, the protected areas represented only 12.75% of these priority areas. Therefore, we identified the main management strategies to increase the representativeness of priority areas. Our findings are largely consistent with previous reports in the Neotropical region, highlighting the need to assign a larger area for conservation purposes.

Analizamos la distribución espacial de los reptiles amenazados y de distribución reducida del pastizal Pampeano, una región con elevada influencia humana en el centro-este de la Argentina. Usamos ejemplares colectados en campo y de museos combinados con variables ambientales de alta resolución para reconocer patrones de distribución comunes y las variables que mejor los explican, estimar el hábitat adecuado para cada especie, identificar las áreas prioritarias de conservación y finalmente proporcionar una prioridad de conservación y manejo relacionada con las áreas protegidas actuales. Los modelos de distribución divergieron en dos patrones de distribución según las especies de distribución reducida: hábitat adecuado para la mayoría de las especies en los pastizales de altura del ambiente serrano, y hábitat adecuado para Liolaemus multimaculatus en los pastizales de las dunas costeras. El grado-días de desarrollo fue la variable ambiental más informativa para la construcción de los modelos de distribución, seguida de la evapotranspiración potencial anual y la estacionalidad de la temperatura. Propusimos áreas prioritarias basadas en dos algoritmos de conservación diferentes: la función de beneficio aditivo, que favorece los ambientes serranos y de dunas, priorizando áreas con una alta riqueza de especies de distribución reducida, y la zonificación del área núcleo, que prioriza la ocurrencia de todas las características de la biodiversidad, indicando además áreas fragmentadas en los alrededores con bajo índice de influencia humana, pero que carecen de las especies estudiadas. Independientemente del algoritmo utilizado, nuestros resultados mostraron que las áreas protegidas existentes en la región no son suficientes para proteger a los reptiles de distribución reducida. Protegiendo al menos el 5% de las áreas prioritarias con mayores valores de conservación, y considerando el costo del índice de influencia humana, las áreas protegidas representaron solo el 12,75% de estas áreas prioritarias. Por lo tanto, identificamos las principales estrategias de manejo para aumentar la representatividad de las áreas prioritarias obtenidas. Nuestros hallazgos son en gran parte consistentes con los estudios previos en la región Neotropical, destacando la necesidad de asignar un área más grande para propósitos de conservación.

The Malvasá rocket frog, Hyloxalus pinguis, is a poorly studied species with a restricted distribution and limited data on its natural history. Its taxonomic status is also uncertain, with some researchers considering it to be a junior synonym of H. pulchellus. We explore the differences between H. pinguis and other species within the genus, update its distribution, including two new localities, describe its vocalizations, and provide the first genetic data and images in life. The species is known exclusively from disturbed areas within high Andean ecosystems in southwestern Colombia at 2,930–3,205 m above sea level (a.s.l.). All new localities were close to small creeks and wetlands. The vocalizations comprise a long train of single notes with 2–13 notes per call, 42–43 notes per minute, and a dominant frequency of 3,488–4,048 Hz, which differs from related species in the genus. Mitochondrial data suggest that H. pinguis is sister to H. delatorreae and not part of the H. pulchellus clade as previously suspected. Two specimens described as H. pulchellus are placed separately from the main H. pulchellus clade and require taxonomic revision, including a specimen from Monte Olivo (Ecuador) that groups with H. pinguis but is highly divergent (uncorrected pairwise distance of 3.9% for 16S). This could either be a divergent mitochondrial lineage of H. pinguis that would extend its range substantially to the south or be an undescribed taxon in need of further study. Overall, the mitochondrial phylogenetic reconstructions, genetic distances, and distinct vocalization calls suggest that H. pinguis is a valid species and not a junior synonym of H. pulchellus, and its small known distribution make it a conservation priority. Further systematic research on Hyloxalus is needed, including the collection of nuclear genetic data, to fully understand this understudied genus that likely harbors additional undescribed diversity.

Capital breeders are animals that breed with the stored energy they have gathered prior to the reproductive event. The amount of energy stored by a given individual can be quantified using morphological measurements and estimating a condition index that can help study the reproductive biology of wild-caught animals. Several condition indices have been used to study the biology and natural history of snakes, with the residual of the log-transformed data being one of the most popular. Here, I develop a simple condition index that assumes that the animals do not change shape throughout life except for changes in condition. This condition with isometry assumption (CIA) is unbiased for all size classes and simple to calculate. With data of animals whose breeding condition was known, I determine a cutoff of 0.875. Animals with a higher condition had a high chance of breeding, while those with lower condition did not. This method correctly predicts the breeding status of 94% of the observations. Using the same data set, I tested the residuals of the log-transformed regression and found far worse results. The CIA was also able to predict breeding status in other snakes opportunistically found in the study. The fact that it is possible to reliably predict the breeding status of anacondas based on their condition confirms that anacondas are capital breeders.