Showing papers on "Rhinella schneideri published in 2011"
01 Jan 2011
TL;DR: The diet of Rhinella schneideri is described based on the analysis of the stomach contents of 18 specimens from an area within the Cerrado, Central Brazil, finding 842 items belonging to 11 prey categories, including the plant material category.
Abstract: This study describes the diet of Rhinella schneideri based on the analysis of the stomach contents of 18 specimens from an area within the Cerrado, Central Brazil. We found 842 items belonging to 11 prey categories, including the plant material category. The most important prey categories for R. schneideri were Insect larvae, Coleopteran and Formicidae. Numerical and volumetric niche breadths of R. schneideri were 3.35 and 1.00, respectively. According to its diverse diet and abundance, R. schneideri may be considered a generalist and opportunist species.
31 citations
01 Jan 2011
TL;DR: Results indicate that the methanolic extract of R. schneideri poison acts primarily presynaptically to enhance neurotransmitter release in this avian preparation.
Abstract: The neurotoxicity of a methanolic extract of toad (Rhinella schneideri) poison was examined in chick biventer cervicis preparations. The methanolic extract (1, 3, 10 and 30µg/ml) caused concentration-dependent blockade at the three highest concentrations (time for 50% blockade, mean±SEM: 84±10, 51±3 and 12±0.8min for 3, 10 and 30µg/ml, respectively; n=6-8 each) that was preceded by significant, transient facilitation at 10μg/ml. Contractures to exogenous ACh (110μM) or KCl (20mM) were unaffected by the blockade. In curarized (d-Tc, 1μg/ml) preparations, the extract (10µg/ml) caused complete, irreversible blockade that persisted after extensive washing. The extract did not significantly alter the creatine kinase release or morphology of biventer cervicis muscle. These results indicate that the methanolic extract of R. schneideri poison acts primarily presynaptically to enhance neurotransmitter release in this avian preparation.
10 citations
TL;DR: Karyotypic features of the five species of the family Bufonidae from the central area of Argentina are described, and discriminant analysis was used to separate the species, with a highly significant classification rate of 80% and P < 0.0001.
Abstract: In this study karyotypic features of the five species of the family Bufonidae from the central area of Argentina are described. The species are Rhinella achalensis, Rhinella arenarum, Rhinella fernandezae, Rhinella schneideri and Melanophryniscus stelzneri. The metaphases were obtained from intestinal and testis cells, using conventional techniques. Twenty metaphasic figures per individual were analyzed and the total length of each chromosome and the length of the four arms were measured. The obtained measurements were processed using Excel 2000 to obtain the average length of the arms p and q, the arm ratio, the centromeric index, the relative chromosome length and the relative arm length. All species showed karyotype 2n = 22, and karyotype formula of 6: 5. Pairs one to six were large, with a relative chromosome length between 18.64–7.59%; pairs seven to eleven were small, with a relative chromosome length between 7.18–2.42%. In all species the chromosome morphology was metacentric or submetacentric. Karyotype and ideograms were made for all species, based on morphometric parameters of the chromosome complement. Finally, discriminant analysis was used to separate the five species analyzed, with a highly significant classification rate of 80% and P < 0.0001. These results agree, in general, with those presented by other authors, however, in M. stelzneri detailed karyological studied have not been made so far, thus this work represents a significant contribution to the karyotypic decryption features of this species and the Rhinellla species from central area of Argentina.
8 citations
TL;DR: The genetic diversity of Rococo toad populations in the highly disturbed landscape of the north-western region of the Brazilian state of Sao Paulo was analysed using microsatellite markers, suggesting that the species has a considerable capacity for dispersal, allowing it to maintain a relatively homogeneous population, even under intense human pressure.
Abstract: The reduced vagility and philopatric behaviour of most amphibians make them especially vulnerable to the effects of habitat fragmentation, in particular the loss of genetic variation. However, almost no data are available on the effects of agricultural practices on populations of Neotropical amphibians. Here, the genetic diversity of Rococo toad (Rhinella schneideri) populations in the highly disturbed landscape of the north-western region of the Brazilian state of Sao Paulo was analysed using microsatellite markers. Two areas were sampled – one dominated by open pastures (four populations) and the other by sugar cane plantations (two populations) – in an attempt to evaluate the possible influence of the type of anthropogenic matrix on genetic variability and gene flow (dispersion). The populations presented a relatively uniform genetic stock, with low levels of inbreeding (Fis) and high levels of admixture between localities (Fst, Rst, STRUCTURE) indicating no genetic subdivision. The results indicated relatively high levels of recent migration among sites (m) and no isolation by distance. The analyses also found that historical and contemporary rates of migration among populations were broadly similar. Overall, then, neither type of matrix appeared to have an effect on the connectivity of the Rococo toad populations. This suggests that the species has a considerable capacity for dispersal, allowing it to maintain a relatively homogeneous population, even under intense human pressure.
6 citations
2 citations