Climate change is a global phenomenon that will generate profound changes in biodiversity in the near future. Studies have reported negative impacts of climate change for South American amphibians; however, for Andean species such as Rhinella spinulosa, the potential response to the effects of climate change is unknown. Using ecological niche models, we estimate the potential distribution of R. spinulosa, identifying the environmental variables that explain its distribution and projecting predictions in climate change scenarios to elucidate their impact on the distribution pattern. The results revealed that the variables of elevation (48.7%), mean temperature of the hottest quarter (44.2%), and topographic humidity index (3.2%) were the most important contributors to the model and are predictors of the distribution of R. spinulosa. The most suitable areas for its distribution are its current range, extending to the north, as well as on the western Andean slope and Argentine Patagonia. Predictions for the future (year 2080) under two scenarios (benign and severe) coincide with the distribution predicted for the current one. Climatic conditions will not be considerably different in the distribution area of R. spinulosa, which may be due to the buffer effect of the mountain range. However, freshwater ecosystems will be more at risk from climate change, which could affect the reproductive success and survival of amphibians. Therefore, we recommend evaluating water availability at a local scale to understand the potential changes in the geographic distribution of R. spinulosa.

El cambio climático es un fenómeno global que podría generar profundos cambios en la biodiversidad en el futuro cercano. Estudios reportan impactos negativos del cambio climático para anfibios sudamericanos, sin embargo, para especies andinas como Rhinella spinulosa, la potencial respuesta de los efectos del cambio climático es desconocida. Usando modelos de nicho ecológico (ENM), nosotros estimamos la distribución potencial de R. spinulosa, identificando las variables ambientales que explican su distribución y proyectando predicciones en escenarios de cambio climático para elucidar su impacto sobre los patrones de distribución. Los resultados revelaron que las variables altitud (48.7%), temperatura media del trimestre más cálido (44,2%) y el índice de humedad topográfica (3,2%) fueron los contribuyentes más importantes al modelo y son predictores de la distribución de R. spinulosa. Las áreas más adecuadas para su distribución es su rango actual, extendiendo su rango hacia el norte, así como en la vertiente occidental de los Andes y la Patagonia Argentina. Las predicciones para el futuro (año 2080) bajo ambos escenarios (benigno y severo) coinciden con la distribución predicha actual. Las condiciones climáticas no serán considerablemente diferentes en el área de distribución de R. spinulosa, lo que puede deberse al efecto amortiguador de la cordillera. Sin embargo, los ecosistemas de agua dulce estarán en mayor riesgo por el cambio climático, que podría afectar el éxito reproductivo y la supervivencia de los anfibios. Por lo tanto, recomendamos evaluar la disponibilidad de agua a escala local para entender cambios potenciales en la distribución geográfica de R. spinulosa.

The present study predicts that helminth community diversity and parasite transmission are influenced by host behavior and its habitat. This prediction was tested by analyzing for the first time the helminth community of Lepidobatrachus llanensis, an aquatic species that inhabits exclusively ephemeral water bodies in the Dry Chaco ecoregion. In the drought periods, L. llanensis burrows underground and forms a cocoon to minimize water loss, emerging again in the rainy season (e.g., in summer months). A total of 21 frogs was examined for parasites. Parasite community structure was analyzed using helminth parasite richness, diversity, and abundance. The helminth community of this frog consisted of 17 species, composed mostly of platyhelminth species (76%), followed by nematodes (24%). Ophiotaenia sp. was most prevalent (71%, confidence interval [CI]: 51.4–90.6%), followed by Choledocystus elegans (57%, CI: 35.8–78.2%). Infected frogs harbored a maximum of seven helminth species. At the infracommunity level, the mean species richness was 4.24 ± 1.79 per infected frog. Parasites were found in all major organs, with highest prevalence in the body cavity. Helminth species showed a typical aggregated pattern of distribution with unequal abundances. Parasite transmission to the frog host occurs by oral ingestion and skin penetration. As predicted, we found that the composition of the parasite community of this aquatic frog included multiple helminths, including parasitic species characteristic of both aquatic and terrestrial life cycles, with greater occurrence of trematodes that likely benefit from seasonal host aggregation during the rainy period associated with their reproductive strategies and by environmental factors such as seasonal dwelling in dry soil. This behavior in an otherwise aquatic frog enables infections by nematodes (L₃₎ with a terrestrial life cycle absent from other aquatic frogs from South America.

Selective pressures vary throughout the range of a species distribution, thus favoring different phenotypes. Climate gradients in particular exert selection on the ecological and physiological performance of organisms, which often promotes morphological variation. In Patagonia, a region with harsh climatic conditions, the sister genera Phymaturus and Liolaemus include several widely co-distributed clades. One example is the Liolaemus bibronii complex and the Phymaturus patagonicus clade; these lineages differ in both morphological characteristics and life-history strategies. Co-distributed species may be similarly affected by shared environmental variables that predominate in their distributions, including patterns of morphological variation. In this study we identify and compare patterns of morphological variation in relation to geographical distribution. We used body size and head shape of species of the L. bibronii complex and the P. patagonicus clade throughout their distributions in Patagonia, and quantified the relationships between morphological variables with latitude and climatic variables. The results showed co-variation of body size and head shape between latitude and climatic variables in both clades, but these do not follow an evident pattern of morphological variation in co-distributed representatives of sister clades with different life histories and evolutionary characteristics.

The advertisement call plays a fundamental role in species recognition in Oreobates. Despite the relevance of this taxonomic character, the advertisement call has not been described for more than half of the species of these direct-developing frogs. We describe the advertisement call of O. berdemenos from its type locality in Jujuy province, Argentina. We confirm the taxonomic identity of voucher specimens as O. berdemenos through molecular and morphological analyses. The advertisement call of O. berdemenos is a melodious trill composed of 10–16 notes with modulated amplitude and frequency. We compared the advertisement call of O. berdemenos to that of two populations assigned to O. discoidalis from Argentina and Bolivia. On this basis, we conclude that the population from Argentina is O. berdemenos, and we suggest that the taxonomic identity of the Bolivian population should be reviewed. We also describe the aggressive vocalization repertoire of O. berdemenos and compare territorial and encounter calls with the vocal repertoire previously assigned to O. discoidalis. With the present work, the advertisement calls and vocal repertoires of two of the three Oreobates species of Argentina have been described.

El canto de anuncio juega un rol preponderante para el reconocimiento de las especies del género Oreobates. A pesar de la relevancia de este caracter taxonómico, más de la mitad de estas ranas de desarrollo directo carecen de la descripción de sus cantos. En este trabajo describimos el canto de anuncio de O. berdemenos en su localidad tipo en la provincia de Jujuy, Argentina. Mediante análisis molecular y morfológico confirmamos la identidad taxonómica de los ejemplares de referencia como O. berdemenos. El canto de anuncio de O. berdemenos es un trino melodioso compuesto por 10–16 notas con amplitud y frecuencia moduladas. Comparamos el canto de anuncio de O. berdemenos con la descripción de los cantos asignados a la especie O. discoidalis en dos poblaciones de Argentina y Bolivia. Concluimos que el canto de Argentina pertenece a O. berdemenos y sugerimos que la identidad taxonómica de la población registrada en Bolivia debe ser revisada. Además, describimos el repertorio de vocalizaciones agresivas de O. berdemenos y comparamos los cantos territorial y agresivo con los previamente descritos para O. discoidalis. Con el presente trabajo, dos de las tres especies de Oreobates de Argentina cuentan con una descripción formal de sus cantos de anuncio y sus repertorios vocales.

We studied the lizard assemblage from Vale Natural Reserve in Espírito Santo state, southeastern Brazil, and evaluated the species distribution in three vegetation types with different levels of habitat heterogeneity, including dense forest environments and open areas with sandy soil. We conducted field sampling from September 2017 to January 2018 and used 30 standardized transects of 500 m in length, at least 1 km apart between them, distributed in the vegetation: coastal plain forest, sandy soil forest, and natural grassland. Lizards were sampled in the transects using the method of active search, by only one observer on each transect. We recorded 185 lizards, belonging to 16 species from eight families. We conclude that lizard assemblage in the studied area differs in relation to the richness and abundance among the vegetation types, with species being widely distributed in the three environments studied and species being characteristically exclusive to some habitats in the mosaic. In this context, there is a fundamental importance in the conservation of these environments, as impacts in some of the vegetation types can cause a population decline of some species.

The Liolaemus boulengeri group is part of the subgenus Eulaemus, genus Liolaemus. This group is widely distributed in Argentina, Bolivia, Chile, and Paraguay, as well as in the Peruvian Titicaca basin and the coasts of Brazil and Uruguay. Here, we combined the revision of a fossil record of Liolaemus, dated at 20 million years (Myr), with relaxed molecular clock analysis to provide a time-calibrated, molecular-based phylogenetic hypothesis including 90% of the group's known species. We found the Liolaemus boulengeri group (= L. boulengeri section) formed by three main groups, the L. wiegmannii, L. anomalus, and L. darwinii-melanops groups. We performed biogeographic analyses applying Bayesian Binary (BBM), Dispersion-Extinction-Cladogenesis (DEC), and Statistical-Dispersion-Vicariance (S-DIVA) and found that the ancestral area of the L. boulengeri group was likely located in central-west Argentina and reached its current distribution after a series of dispersal and vicariance events. These processes may have been favored by a period of climatic stasis which occurred at the beginning of the group's diversification, around 41 Myr. The congruence of the results of all three biogeographic analyses evidences new hypothetical historical distributions and events which led to the current species distribution of the L. boulengeri group.

El grupo de Liolaemus boulengeri es miembro del subgénero Eulaemus, dentro del género Liolaemus. Este grupo se distribuye en Argentina, Bolivia, Chile y Paraguay, así como en el sureste de Perú, en la cuenca del Titicaca y las costas de Brasil y Uruguay. En este trabajo obtuvimos una hipótesis filogenética basada en evidencia molecular, incluyendo el 90% de las especies conocidas para el grupo. También, obtuvimos un árbol temporalmente calibrado, usando un reloj molecular relajado y un registro fósil de Liolaemus, datado en 20 millones de años. Encontramos al grupo de Liolaemus boulengeri (= sección de L. boulengeri) formado por tres grupos principales, los grupos de L. wiegmannii, L. anomalus y L. darwinii-melanops. Realizamos un análisis biogeográfico aplicando: Bayesian Binary (BBM), Dispersion-Extinction-Cladogenesis (DEC) y Statistical-Dispersion-Vicariance (S-DIVA), encontrando que el área ancestral del grupo de L. boulengeri está ubicada en el Centro-Oeste de Argentina. Desde ahí, debido a una combinación de eventos de dispersión y vicarianza, las especies de este grupo alcanzaron su distribución actual. Estos procesos podrían haberse favorecido por un periodo de estasis climática que ocurrió al comienzo de la diversificación del grupo, hace alrededor de los 41 millones de años. La congruencia de los resultados de los tres métodos nos permitió hipotetizar las distribuciones históricas y los eventos que podrían haber afectado la distribución actual de las especies del grupo de L. boulengeri.

Ecological factors such as environment, habitat, and accompanying gradients affect the morphological characteristics of species. Different environmental conditions may induce phenotypic dissimilarities in populations of a species or between closely related species causing character evolution, or they may cause phenotypic plasticity as a response to abiotic and biotic changes in living habitats. The family Bufonidae (Amphibia: Anura) contains stereotypical toads with basic phenotypic features like dry warty skin characterized by spinosity. Keratinized spines were handled in previous studies on the genus Bufo. The studies were focused on the morphological shape differences and mostly intra-specific variations, but ecological parameters were not sufficiently investigated. In this study, we tested the relationship between elevation and the intensity of keratinized spines for Bufo bufo and B. verrucosissimus species in Türkiye. We also assessed intra and interspecific variations for both species based on the spinosity. According to the results of a chi-squared test, a statistically significant difference was found in the intensity of keratinized spines between the sexes of B. bufo. Males mostly had smooth skin without spines, whereas most females had slightly keratinized spines. There was no difference in terms of intensity of keratinized spines between sexes in B. verrucosissimus species. For interspecific variations, we found that female specimens differed in terms of intensity of keratinized between species. Accordingly, all B. bufo females had heavily keratinized spines, whereas most of B. verrucosissimus females had smooth skin. We found statistically significant negative relationships between elevation and intensity of keratinized spines for both species. Accordingly, we assume that the observed disparity related to the intensity of spines demonstrates a species-specific character evolution between species. The differences between elevations might be associated with local climatic conditions and defense strategies against predators in the living space.

Crocodilians are known to interact substantially with humans. Conflicts are observed when both species share a habitat and are documented worldwide. In Costa Rica, this conflict has been detected along with increases in human activities. For this reason, we undertook a study to identify potential crocodile habitats and the areas of interaction with humans on the Pacific and Caribbean coasts and the Northern Zone of Costa Rica. This work was performed during 2019 and 2020 in both regions, and determination of the potential habitat of crocodiles was made through analysis of the elevation, topography, drainage net, flooding areas, mangrove areas, and rivers and their outlets. To identify areas of human–crocodile interactions, a map of the potential habitat was used and changes to those habitats were analyzed (e.g., road density, population density, and the density of the populated core). The relationship between species was established to predict interaction hotspots between humans and crocodiles. The habitats with high potential for crocodiles on the Pacific slope correspond to 18% of the study area, and the medium potential habitat to 54%. Within the Central Pacific, there are few areas at higher elevations or with a large index of urbanism; these low potential habitats represent 27% of the study area. In the Central Pacific, the high and medium potential habitats together represent 72% of the study area. On the Caribbean slope, the high potential habitat was identified in areas closer to the coast mainly in the North and Central Caribbean (corresponding to 29% of the study area), while 66% of the study area was labeled as medium potential habitat. In the Northern area, most of the habitat was identified as medium potential, there being only small fragments recognized as high potential habitat. In the Northern Zone and Caribbean Zone, the areas at higher elevation with some land development were identified as low potential habitat (4%). Importantly, 96% of the area of the Caribbean slope and the Northern Zone were identified as high or medium potential habitat.

Se sabe que los cocodrilos son un grupo que interactúa intensamente con los humanos. Los conflictos se observan cuando ambas especies comparten el hábitat lo cual está documentado en todo el mundo. En Costa Rica, este conflicto se ha detectado en zonas que presentan actividades humanas. Por esta razón, identificamos el hábitat potencial del cocodrilo, además identificamos las áreas de interacción con humanos en las costas del Pacífico, Caribe y la Zona Norte de Costa Rica. Este trabajo se realizó durante 2019 y 2020 en ambas regiones, y la determinación del hábitat potencial de los cocodrilos se realizó mediante el análisis de la altitud, topografía, red de drenaje, áreas de inundación, áreas de manglares y ríos y sus desembocaduras. Para identificar áreas de interacciones entre humanos y cocodrilos, se utilizó un mapa del hábitat potencial y se analizó la alteración del hábitat (densidad de carreteras, densidad de población y densidad de población). La relación entre especies se estableció para predecir puntos críticos de interacción entre humanos y cocodrilos. Los hábitats con alto potencial para cocodrilos en la vertiente del Pacífico corresponden al 18% del área de estudio, el hábitat de potencial medio (54%). Dentro del Pacífico Central hay pocas áreas de elevada altitud o con un evado índice de urbanismo, estos son hábitats de bajo potencial y representan el 27% (del área de estudio). En el Pacífico Central, los hábitats de potencial alto y medio juntos representan el 72% (del área estudiada). En la vertiente del Caribe, el hábitat potencial alto se identificó en áreas más cercanas a la costa principalmente en el Caribe Norte y Central (29% del área de estudio), mientras que el 66% del área se etiquetó como hábitat de potencial medio. En la Zona Norte, la mayor parte del hábitat se identificó como de potencial medio, habiendo solo pequeños fragmentos reconocidos como hábitat potencial alto. En la Zona Norte y la Zona del Caribe, las áreas de mayor altitud con algún desarrollo territorial fueron identificadas como hábitat de bajo potencial (4%). Es importante destacar que el 96% del área de la vertiente del Caribe y la Zona Norte se identificaron como hábitat de alto o mediano potencial.

The objective of this study was to determine the growth pattern of farmed Crocodylus moreletii individuals from hatchling to juvenile. A total of 3,743 crocodiles (3,098 males and 645 females) were included. Crocodiles hatched from artificially incubated eggs. Individuals were classified into three age categories: (1) neonate (0–4 months), (2) developing (4–12 months), and (3) juvenile (12–27 months). Seven biometric evaluations were conducted. The first one was at 4 d after hatching, and the following evaluations were at 4, 8, 12, 17, 22, and 27 months of age. In each evaluation, the total length, weight, and sex of each individual were registered. Crocodiles were subsequently classified into three growth groups: (1) fast: length and weight greater than 1 SD from the mean, (2) average: length and weight within 1 SD from the mean, and (3) slow: length and weight lower than 1 SD from the mean. Linear polynomial (LPN), quadratic polynomial (QPN), and three-parameter sigmoidal (SIG3) models were used to evaluate length and weight as a function of age to describe growth. For length and weight, SIG3 and QPN, respectively, produced the highest R² in all growth groups and the general population. LPN did not fit the weight data. The models that best fitted length and weight in relation to age were SIG3 and QPN, so both could be used to evaluate the growth pattern in other populations of farmed young Crocodylus moreletii.

El estudio determinó el patrón de crecimiento de individuos de Crocodylus moreletii criados en granja desde neonatos hasta juveniles. Se incluyeron 3743 cocodrilos (3098 machos y 645 hembras) que eclosionaron de huevos incubados artificialmente. Los animales se clasificaron en tres categorías de edad: (1) Neonatos (0–4 meses), (2) en desarrollo (4–12 meses), y (3) juveniles (12–27 meses). Los neonatos incluyeron recién eclosionados (0–4 días) y de 4 días a 4 meses. La temperatura ambiente a la que se mantuvieron fue 32.8 ± 0.2°C recién eclosionados, 31.8 ± 2.3°C neonatos y 31.5 ± 3.1°C en desarrollo y juveniles. La dieta de los animales se basó en hígado de pollo picado y harina de pescado adicionados con vitaminas A, D3, E, B12, B3 y calcio y estuvo disponible ad libitum. Los neonatos y en desarrollo se alimentaron diario y los juveniles seis veces por semana. Se hicieron siete evaluaciones biométricas en todos los animales. La primera fue 4 días después de eclosionar y las siguientes a los 4, 8, 12, 17, 22 y 27 meses de edad. En cada evaluación se registró longitud total, peso y sexo de cada individuo. Se usó estadística descriptiva para determinar la media ± DE de longitud y peso para hembras y machos en cada evaluación. Los cocodrilos se clasificaron en tres grupos de crecimiento: (1) Rápido: longitud y peso mayor de 1 SD de la media; (2) promedio: longitud y peso dentro de 1 SD de la media; (3) lento: longitud y peso menor de 1 SD de la media. Se usó un modelo polinomial lineal (LPN), polinomial cuadrático (QPN) y sigmoidal de tres parámetros (SIG3) para evaluar longitud y peso en función de la edad para describir el crecimiento. Para longitud y peso, SIG3 y QPN, respectivamente, tuvieron la mayor R² en todos los grupos y la población general. El LPN no se ajustó a los datos del peso. Los modelos que mejor se ajustaron a longitud y peso en el estudio fueron SIG3 y QPN, y por tanto podrían usarse para evaluar el patrón de crecimiento en otras poblaciones de Crocodylus moreletii jóvenes en granja.

Ivermectin (IVM) is an antiparasitic widely used in veterinary medicine around the world, and cattle injection with IVM is a common practice in wetlands of the Middle Paraná River. Approximately 45% of administered IVM is eliminated in livestock feces. Immediately after injection, cattle enter wetland for feeding and drinking, incorporating feces with IVM into aquatic systems, where it accumulates in the substrate, especially in sediments rich in organic matter. Thus, our objective was to experimentally assess the habitat selection of nektonic (Boana pulchella) and benthic (Physalaemus albonotatus) tadpoles between patches of substrate with and without IVM. The experimental units consisted of quadrangular plastic trays with the bottom divided into four internal quadrants, two filled to 1 cm depth with IVM-free substrate and the other two with substrate containing IVM (nominal IVM concentrations were 3000 ng/g substrate fresh weight), filled to 3 cm depth with water. We placed one tadpole in the center of each tray (B. pulchella: n = 22; P. albonotatus: n = 50) and visually recorded its position (IVM-free or IVM quadrants) every 1 h during the first 10 h, with a final observation at 24 h. The recovery concentration of IVM in the IVM quadrant substrate was 73.95% (percentage of target concentration) and was not detectable in the IVM-free quadrant. The frequency of observations of tadpoles was significantly higher in IVM-free quadrants than in IVM quadrants (B. pulchella: 57%; P. albonotatus: 58%), and this pattern did not differ between nektonic and benthic tadpoles. Thus, tadpoles of both species selected the quadrants free of IVM. The response of tadpoles to IVM merits investigation in a wider spectrum of species and different concentrations to better understand the effects of this emergent pollutant on amphibians.

La ivermectina (IVM) es un antiparasitario muy utilizado en medicina veterinaria en todo el mundo. Aproximadamente el 45% de la IVM administrada se elimina por las heces del ganado. En los humedales del río Paraná Medio, la inyección de IVM al ganado es una práctica común. Inmediatamente después de la inyección, el ganado ingresa al humedal para alimentarse y beber, incorporando heces con IVM a los sistemas acuáticos, donde se acumula en el sustrato, especialmente en sedimentos ricos en materia orgánica. Bajo este contexto, nuestro objetivo fue evaluar experimentalmente la selección de hábitat de renacuajos nectónicos (Boana pulchella) y bentónicos (Physalaemus albonotatus) entre parches de sustrato con y sin IVM. Las unidades experimentales consistieron en bandejas cuadrangulares de plástico con el fondo dividido en cuatro cuadrantes internos, dos de ellos llenos de 1 cm de profundidad con el sustrato libre de IVM y los otros dos llenos del sustrato con IVM (las concentraciones nominales de IVM fueron 3000 ng/g^-1 peso fresco del sustrato) y llenas de agua (3 cm de profundidad). Colocamos un renacuajo en el centro de cada bandeja (B. pulchella: n = 22; P. albonotatus: n = 50) y registramos visualmente su posición (en cuadrantes libres de IVM o IVM) cada 1 h durante las primeras 10 h, y una observación final luego de 24 h. La concentración de recuperación de IVM en el sustrato del cuadrante IVM fue del 73.95% (porcentaje de la concentración objetivo), mientras que no fue detectable en el cuadrante libre de IVM. La frecuencia de observaciones de renacuajos fue significativamente mayor en los cuadrantes libres de IVM que en los cuadrantes de IVM (B. pulchella: 57%; P. albonotatus: 58%), y este patrón no difirió entre los renacuajos nectónicos y bentónicos. Así, los renacuajos de ambas especies seleccionaron los cuadrantes libres de IVM. La respuesta de los renacuajos a la IVM debe investigarse en un espectro más amplio de especies y diferentes concentraciones para comprender mejor los efectos de estos contaminantes emergentes en los anfibios.