We describe the seasonal variation in the male reproductive cycle of Bothrops pubescens, a pitviper from southern Brazil. All specimens were collected in the state of Rio Grande do Sul, a region with climates varying from subtropical to subtemperate and temperate. We characterized male reproduction considering histological analyses of the testes, sexual segment of the kidneys (SSK), and ductus deferens, as well as macroscopic indicators of reproductive activity (testes volume and ductus deferens width in the distal portion) to allow comparisons. We also evaluated the seasonal variation of epithelial height and tubule diameter of the testes and SSK. These reproductive parameters showed significant seasonal variation, with a high increase in summer and a peak in autumn for spermatogenic and SSK activity. Courtship behavior occurs on March (end of summer/beginning of autumn), in synchrony with sperm production and SSK hypertrophy. Sperm storage occurred in the ductus deferens throughout the year. We detected an ampulla ductus deferentis in the distal portion of the ductus deferens in some individuals. Male B. pubescens exhibit a seasonal reproductive cycle, and the use of microscopic methods was highly informative for supporting this conclusion.

Nós descrevemos a variação sazonal no ciclo reprodutivo de Bothrops pubescens, uma espécie de serpente da subfamília Crotalinae, da região Sul do Brasil. Os machos foram amostrados no estado do Rio Grande do Sul, que é uma região com climas variando de subtropical a subtemperado e temperado. Os ciclos dos testículos, segmento sexual renal (SSR) e ducto deferente foram caracterizados utilizando análises histológicas para descrever o ciclo reprodutivo dos machos. Nós também avaliamos indicadores macroscópicos da atividade reprodutiva (volume do testículo e largura do ducto deferente na região distal) para fins de comparação. Considerando os dados histológicos, foram avaliadas as variações sazonais da altura do epitélio e diâmetro dos túbulos tanto dos testículos quanto do SSR. Estes parâmetros reprodutivos apresentaram variação sazonal significativa, com grande aumento no verão e pico no outono, tanto para a atividade espermatogênica quanto para o SSR. Corte em vida livre ocorre em março (fim do verão/início do outono), em sincronia com a produção de esperma e a hipertrofia do SSR. Estocagem de esperma ocorreu no ducto deferente ao longo do ano. A ampulla ductus deferentis foi observada na porção distal do ducto deferente de alguns indivíduos. O ciclo reprodutivo dos machos de B. pubescens é sazonal e o uso de métodos microscópicos foi essencial para chegar a esta conclusão.

Snakes exhibit considerable variation in reproductive patterns. However, the cycle of the sexual segment of the kidney and the testicular activity remain unknown for most Neotropical snake species. The dipsadine Atractus pantostictus is a fossorial snake species occurring in central and southeastern Brazil. The present study describes the reproductive cycle of males of this species, providing macroscopic and microscopic analyses of testes, ductus deferens, and sexual segment of the kidneys. We classified the cycle of males as pre-nuptial, as the production of gametes in males precedes the mating season. In summer, the specimens underwent testicular regression; thus, the individuals of A. pantostictus presented a discontinuous cyclical pattern in which the gonads or accessory organs become reproductively quiescent for some period during the year. At the population level, our results indicated a seasonal reproductive cycle. The sexual segment of the kidney was hypertrophied during the spring, corresponding to the mating season.

Several species of crocodilians consume, digest, and benefit from plant nutrients, and the animal food industry has made important efforts to use different plant materials in the development of new pellets for these animals. This information is very important within the ambit of captive breeding and crocodilian nutrition. The search for plants to supplement the diets of crocodilians is important because it may help to satisfy the nutritional demand of captive crocodilians and reduce the costs of their feeding and production. These initiatives have been mainly focused on animals such as fish and poultry, although some research has also been carried out with crocodilians. The demand for crocodilian skin and meat spiked during the 1990s. Since then, efforts have been amplified to investigate the use of different plants in the development of artificial diets to replace or complement the diet of different crocodile species, without interfering with product quality, health, and animal development while keeping production cost low. To achieve this, the existing information about the main and new sources of plant raw materials used to feed crocodilians must be known.

Many recent studies have shown that amphibian populations have been affected by a variety of causes including climate change, pollution, habitat destruction, and disease. Such drivers could also influence the physiological and behavioral reproductive events of individuals. Rhinella arenarum is an amphibian species that has been extensively used as an experimental model for biological studies. This is an ecologically important species due to its abundance and wide distribution in South America. Our research on the female gonad of R. arenarum conducted in the last three decades has allowed us to observe that the competence of the ovary of this species has been slowly modified over the years, manifested by an increase in oocyte lysis during in vitro assays. To better understand the changes, a retrospective analysis of data from the last three decades was performed in order to quantify oocyte maturation and lysis in the presence of different incubation mediums. Data from three sampling years (1993, 2005, and 2018) were selected, and percentages of oocyte maturation and lysis were compared. Results show a significant decrease in oocyte maturation and an increase in oocyte lysis in the last sampling year. We also examined the climate conditions of the habitat of R. arenarum in each sampling year and their variation as a possible driver of decreased ovarian functionality. A significant increase in minimum temperatures, solar radiation, and relative humidity is reported. Alterations in the climate conditions of the natural habitat of R. arenarum might be one of many factors responsible for the decrease in ovarian functionality. Further analysis of the impact of the ongoing climate change on several aspects of amphibian phenology is needed to strengthen understanding of population declines and promote species conservation.

We studied gametogenesis and reproduction of Bokermannohyla nanuzae at an Atlantic Forest site in southeastern Brazil from August 2011 to July 2012. We observed frogs with mature germ cells almost year-round, indicating continuous gametogenesis. However, advanced gonad maturation occurred in wet months, when we observed females spawning and spermiated males. We observed calling males with mature testes in all bimesters but spermiated males only from October to January. This pattern of continuous calling may be associated with male strategies to be selected by females within male choruses. We did not observe males with testes at rest or females with ovaries at rest, and throughout the year we observed spermatogenic cells in all developmental stages in males as well as vitellogenic oocytes in different maturation stages and several post-ovulatory follicles in females, indicating that both males and females may be ready to respond to a specific environmental cue to release their gametes or even be able to breed multiple times throughout the year. This promptness to breed may be adaptive as it allows frogs to reach mature stages faster when environmental conditions are suitable for breeding and even breed more than once per breeding season.

Anurans that inhabit dry habitats exhibit particular life histories and possess morphological features associated with burrowing behavior (e.g., specialized metatarsal tubercles, short hind limbs relative to body size). The Neotropical genus Pleurodema includes 15 species distributed mainly in arid and semiarid environments. Backward burrowing behavior has been recorded in the genus, as well as the presence of specialized inner metatarsal tubercles. However, morphometric variation associated with burrowing has not been sufficiently studied in Pleurodema. To explore this variation, we scored 13 external body measurements and examined the morphology of the metatarsal tubercles of 615 adult specimens representing 14 species of Pleurodema. We also summarized available data about egg-clutch structure, hatching time, and duration of larval period of all species of the genus. Our results revealed that body shape variation mainly consists of differences in the relative length of the hind-limb elements. Pleurodema brachyops, P. diplolister, P. guayapae, P. nebulosum, P. tucumanum, and P. marmoratum have the shortest hind-limb elements relative to snout–vent length, and all but P. marmoratum also have keratinized inner metatarsal tubercles. The combination of these features has been considered a fossorial specialization on biomechanical grounds. Pleurodema brachyops, P. diplolister, P. guayapae, P. nebulosum, and P. tucumanum also have the shortest hatching time and larval period. A short larval period has been related to arrestment in the elongation phase of anuran limbs. Both burrowing performance and developmental effects could explain the variation in the limb morphology within Pleurodema.

Whereas prey tend to reduce conspicuousness, predators remain active to locate their prey. In particular, mesopredators (i.e., predators situated in the middle of two trophic levels) may be subjected to opposing pressures. Locomotor performance influences predator–prey interactions, and together with behavior can be constrained by morphology. In this study, we test how locomotor performance and foraging behavior of larvae of the predaceous amphibian Ambystoma maculatum are influenced by morphology and exposure to chemical cues from predators and competitors. We test whether tail-injured and uninjured larvae differed in morphology, locomotor performance, and feeding rate. Larger individuals showed higher locomotor performance and prey consumption rate. These were not correlated, but the latter increased subsequent locomotor performance. Neither perceived predators nor competitors affected swimming speed or prey consumption rate. Body size was positively correlated with prey consumption rate only in those individuals not previously exposed to chemical cues from predators and competitors. Finally, tail-injured larvae were smaller, but did not experience reduced speed or prey consumption rates.

Mientras que las presas tratan de pasar desapercibidas para sus depredadores, muchos depredadores permanecen activos para tratar de localizarlas. En particular, los mesodepredadores (es decir, depredadores que se sitúan en la parte media de la cadena trófica) pueden estar sujetos a presiones opuestas. El desempeño locomotor influye en las interacciones depredador-presa, y así como el comportamiento, puede estar restringido por la morfología. En este estudio, testamos cómo la morfología y la exposición a señales químicas de depredadores y competidores afectan al desempeño en la locomoción y el comportamiento de larvas del anfibio depredador Ambystoma maculatum. También testamos si las larvas con cola dañada y sin dañar diferían en morfología, desempeño locomotor y tasas de captura de presas. Los individuos de mayor tamaño mostraron mayor desempeño locomotor y una tasa de captura de presas más alta. Estas no estuvieron correlacionadas, pero la última incrementó el desempeño locomotor subsecuente. La exposición indirecta al riesgo de depredación o la competencia no influenciaron la velocidad de natación ni a la tasa de captura de presas. El tamaño corporal estuvo positivamente correlacionado con las tasas de captura solo en los individuos no expuestos a señales químicas de depredadores o competidores. Finalmente, las larvas con cola dañada fueron más pequeñas, pero no experimentaron reducción alguna en su velocidad o tasas de captura.

Some amphibian species are highly abundant in riparian areas, with high numbers of both froglets and adults. These two age classes commonly have different diets. Studying how dietary differences are associated with ontogeny and the spatial distribution of frogs with respect to water bodies contributes to understanding the role of amphibians in trophic webs and in the biological dynamic of riparian ecosystems. We analyzed the diet, density, and mass of Craugastor berkenbuschii, a leaf-litter frog abundant in riparian areas in tropical forest in southern Mexico. We also estimated the number and biomass of prey consumed per area in relation to distance to streams (near: 0–15 m, far: 45–60 m) and body size. We found no differences in any diet variable between the two distances to streams, but diet composition changed with ontogeny. As snout–vent length increased, the number of prey consumed decreased and stomach content mass and mean prey length increased. Frog density and mass were higher near the streams than farther from the streams. The proportion of large and medium-sized frogs did not vary by distance to the streams, but the proportion of small frogs was marginally higher near the streams. Close to the streams, small frogs consumed a higher estimated invertebrate number per area than did medium-sized frogs, and these in turn more than large frogs. However, farther from the streams, large and medium-sized frogs preyed on a higher number of invertebrates per area than small frogs. Invertebrate biomass consumed did not differ among size classes at either of the distances, but both invertebrate number and biomass consumed by the species were higher near the streams than farther from them. The finding that prey number consumed decreased as frog size increased, together with the strong affinity of the species—particularly of small frogs—to streams, had an effect on estimates of invertebrate consumption. These results implied a higher consumption of invertebrates near than farther from the streams, and a greater impact of small than large frogs on invertebrate numbers in riparian environments.

Algunas especies de anfibios muestran una gran abundancia en áreas ribereñas, con un número alto de ranas recién metamorfoseadas y adultos. Estas dos clases de edad comúnmente exhiben diferencias en aspectos de la dieta. El estudio de cómo las diferencias en la dieta están asociadas con la ontogenia y la distribución espacial de las ranas con respecto a cuerpos de agua contribuye al entendimiento del rol de los anfibios en las redes tróficas y en la dinámica biológica de ecosistemas ribereños. Nosotros analizamos aspectos de la dieta, densidad y masa de Craugastor berkenbuschii, una rana de hojarasca abundante en áreas ribereñas del bosque tropical en el sur de México. Adicionalmente, estimamos el número y biomasa de presas consumidas por área con relación a la distancia a los arroyos (cerca: 0–15 m, lejos: 45–60 m) y al tamaño del cuerpo. No encontramos diferencias en ninguna variable dietética entre las dos distancias a los arroyos, pero la composición de la dieta cambió con la ontogenia de las ranas. Adicionalmente, a medida que aumentó la longitud hocico–cloaca, el número de presas consumidas disminuyó y el peso del contenido del estómago y la longitud media de las presas aumentó. La densidad y masa de las ranas fueron mayores cerca de los arroyos que lejos de los arroyos. La proporción de ranas grandes y medianas no varió entre las distancias a los arroyos, pero la proporción de ranas pequeñas fue marginalmente mayor cerca de los arroyos. Cerca de los arroyos, las ranas pequeñas consumieron un número estimado de invertebrados por área más alto que las ranas medianas, y estas a su vez más alto que las ranas grandes. Sin embargo, lejos de los arroyos, las ranas grandes y medianas consumieron un mayor número de invertebrados por área que las ranas pequeñas. La biomasa de invertebrados consumida no difirió entre las clases de tamaño en ninguna de las distancias, pero tanto el número de invertebrados como la biomasa consumida por la especie fueron mayores cerca de los arroyos que lejos de ellos. El hallazgo de que el número de presas consumidas disminuyó a medida que el tamaño de las ranas aumentó, en combinación con la fuerte afinidad de la especie—particularmente de las ranas pequeñas—a los arroyos, tuvo un efecto en las estimaciones del consumo de invertebrados. Estos resultados implicaron un mayor consumo de invertebrados cerca que lejos de los arroyos, y un mayor impacto de ranas pequeñas que grandes en el número de invertebrados en ambientes ribereños.

In the present study, some demographic life-history parameters (e.g., age structure, age upon attaining sexual maturity, longevity, adult life expectancy, growth, and survival rate) and body size were investigated for the first time in two populations (urban and rural populations) of the rough bent-toed gecko, Cyrtopodion scabrum. A total of 69 (26 males, 30 females, and 13 juveniles) C. scabrum individuals were studied. Our findings indicated that age upon attaining sexual maturity was 2 and 3 years in both sexes. The maximum longevity was 7 years in females and 6 years in males. We did not find a remarkable difference in body size between females and males. When comparing both populations, neither male and female urban individuals nor both individuals together were significantly different from their counterparts from the rural population with respect to the average age and body size. The body size markedly increased with age in both males and females.