Snake venom is an expensive metabolic weapon used for digestion and defense. Detailed studies on the production of venoms are important for the manufacture of antivenoms and for the therapeutic management of snakebites. Bothrops leucurus is one of the snakes of medical importance responsible for a large number of accidents in Northeast Brazil. To establish the correlation between Bothrops leucurus venom (Blv) yield, under captive conditions, and the morphological characteristics (body mass and length), sex and age, 31 specimens were milked during one year, grouped by sex and age (juvenile, adult and long-lived), totaling 106 extractions in that period. We evaluated the electrophoretic profile (SDS-PAGE) under reducing conditions, the 50% lethal dose (LD50) and the minimum coagulant dose (DMC) of the extracted venoms. The body size was positively correlated with venom production in B. leucurus snakes. Regardless of sex and age, the venom showed no differences between liquid and solid composition or between right and left fang, however, the production of venom in females was twice the one found in males and more lethal. The clotting ability was lost as the animals aged, indicating that older snakes are not the best choice for venom pools in the production of antivenoms. These results are important for the choice of animals to antivenom production, and to understand the biological effects of snake venoms under captive conditions.

The mechanism behind the female-biased sexual size dimorphism in snakes (SSD) is usually linked to a delay in females' maturation and/or higher growth rates during their immature phase. Studies on growth rates of immature snakes have been focused on sex differences related to feeding rates instead of food conversion rates. We tested the hypothesis that growth rates of immature female lanceheads are higher than that of immature males and determined if this difference is related to differential food conversion rates between genders. During 18 months, we collected data on growth rates in juveniles from a litter of a species (Bothrops fonsecai) with a female-biased sexual size dimorphism under a controlled feeding regime. Our results showed that females, even receiving the same amount of food than males, presented higher growth rates in all parameters measured (snout-vent length, mass, stoutness, snout-vent length-specific growth rate and mass-specific growth rate). Our data support a mechanism of e...

Knowledge about parasitic fauna provides valuable information on natural history, health, and conservation of the hosts. In this study, we present the parasitological descriptors (prevalence, mean intensity and mean abundance of infection) of the nematodes of Amphisbaena vermicularis, a poorly studied amphisbaenian. We analysed 33 adult specimens (22 males and 11 females) from three Atlantic Forest remnants in the Northeast region of Brazil, characterised by a gradient of anthropogenic disturbance. We recovered 244 nematodes in the intestines of 17 (51.5%) animals: 225 Maracaya graciai (Atractidae) prevalence 42.4%, mean abundance 6.81 ± 3.16, mean intensity 16 ± 6.81 (range 1–100), and 19 Aplectana sp. (Cosmocercidae) prevalence 9.1%, mean abundance of infection 0.57 ± 0.37, mean intensity of infection 6 ± 2.60 (range 2–11). There was no statistically significant difference in the mean intensity of M. graciai infection in relation to the study areas and the sex of the animals. Maracaya graciai was found in all study sites regardless of the level of anthropogenic disturbance, while Aplectana sp. was present only in the most conserved forest remnant or with mid-level disturbance, with higher parasitological indices in the conserved remnant. Therefore, further studies should be carried out to verify the usefulness of Aplectana sp. as an indicator of environmental health and anthropogenic impact. The current study records a new host of M. graciai and Aplectana sp. and also extends the geographical distribution of M. graciai.

The diet of lizards is mainly composed of arthropods. It can be affected by biotic and abiotic factors, which influence the energy supply provided by the composition of the animal´s diet. The richness and abundance of many arthropod species can be influenced by environmental seasonality, especially in the Caatinga ecoregion, due to the rainfall regimes. The present study aims to describe aspects of the seasonal and morphological variation in the lizard Gymnodactylus geckoides diet and their energy content. We collected 157 individuals (63 females, 68 males, and 26 juveniles) at the Catimbau National Park, Northeastern Brazil, of which 72 were analyzed for the dry season and 59 for the rainy season. Our data indicates Isoptera to be the most common prey in G. geckoides’s diet. Energy content, prey number was higher in the dry season, whereas prey volume and glycogen content increased in the rainy season. Proteins and lipids did not show marked differences. The present study represents the first effort to understand variations in G. geckoide’s trophic ecology, indicating that this specie presents a wide variation in their diet, especially when considering seasonal factors, revealing their needs and restrictions according to prey availability and environmental conditions.

Temperature trends influence the behaviour of animals, mainly ectotherms, with thermoregulation led by a contingent of biotic and abiotic factors, such as seasonality and habitat quality, especially regarding nocturnal lizards. Therefore, in the present study, we aimed to analyse the microhabitat use and thermal ecology of Gymnodactylus geckoides in Catimbau National Park, in Pernambuco state, Brazil, considering different landscape conditions (anthropic and conserved), as well as environmental factors (body, air and substrate temperature, humidity and light intensity). We recorded bromeliads, leaf litter, as well as rocky outcrops, fallen trunks and rocks, with the use of microhabitats differing due to the environmental conditions. G. geckoides was mostly active at night, with substrate and air temperatures revealing a high correlation with body temperature. Regarding environmental factors, only light intensity revealed significant variations. The distribution model allowed us to observe G. geckoides inhabiting lower elevations, influenced by microhabitat availability. Our research represents the first effort to create a distribution model for lizards in Caatinga domain, using G. geckoides as an illustrative model to demonstrate the plasticity of species in response to environmental changes, also indicating a high dependency on habitat quality for thermoregulation. This domain provides G. geckoides with a thermally optimal and stable microclimate, maintaining its optimal body temperature requiring low thermoregulatory effort. Our results corroborate with previous studies and predictions and expand prior work regarding the thermal ecology of nocturnal neotropical lizards.

Frogs use different kinds of environment in their life cycle; hence, they may be indicators of pollution and environmental degradation. In the present study, the frogs are relevants to evaluate the harmful effects of waste disposal. We carried out weekly sampling by active search from January to December 2004 in a 1-km stretch of the Gurjaú River, at the Gurjaú State Reserve (SRSG), located in the south of the city of Recife, which is managed by Pernambuco Sanitation Company (COMPESA), maintaining a water treatment plant in the reserve since the damming of the Gurjaú River. COMPESA discharges quarterly the chemical waste from the cleaning of its settling tanks directly into the Gurjaú River, downstream of the water uptake. The study displayed that among 40 species, six were observed near the river: Hypsiboas semilineatus (Spix, 1824), Leptodactylus gr. marmoratus (Steindachner, 1867), Scinax x-signatus (Spix, 1824), Litobathes palmipes (Spix, 1824), Leptodactylus vastus (Spix, 1824), and Pseudopaludicola gr. falcipes (Hensel, 1867). The site located upstream of the waste discharge had much more captures than the site located downstream of it. Based on the physicochemical analysis of the water, we conclude that the activities of COMPESA have high environmental impact.