Abstract:The Cerrado is a tropical savannah with a diversified anuran assemblage, with 209 to 271 known species, of which approximately 51% are endemic. In this study, we report results of an anuran survey performed in the Extractivist Reserve of the Lago do Cedro, located in the northwestern region of the state of Goiás, Brazil. In this area, we recorded 36 anuran species, distributed in five families, from which five species are Cerrado endemics. This high species richness found in the Extractivist Reserve of the Lago do Cedro could be explain by the different vegetational types within the reserve boundaries that promote a high local heterogeneity. Species richness and representativeness per family are similar to other assemblages reported for different areas in the Cerrado domain, being the local anuran assemblage composed by generalist and widely distributed species. The families Hylidae and Leptodactylidae are the most diversified in the studied area, a common pattern found in neotropical assemblages. The Extractivist Reserve Lago do Cedro is an important area for Cerrado conservation because of the anuran diversity and geographic location, which allows the connection among other protected areas within the Araguaia basin.
Local niche-based processes and dispersal are important determinants of assemblage composition and species diversity. However, there is no consensus about the relative importance of niche and spatial processes to explain the distribution of anuran species in tropical systems. In our study, we analyzed the niche and neutral effects on anuran assemblages and found that biotic interactions were a predictor of assemblage structure. The Eltonian concept of niche was the best predictor for the structure of aquatic-breeding anuran assemblages, as species tended to co-occur more often than would be expected by chance. We suggest that the lack of environmental effect could be explained by differences in the pattern of movement between arboreal and non-arboreal anurans. Once there is a reduction in the number of arboreal anurans in open areas, the importance of habitat heterogeneity to explain assemblage composition should decrease. The lack of correlation between the spatial component in our model and species composition is evidence that spatial processes, such as migration, did not play a major role in structuring local assemblages. Anurans are generally assumed as having poor dispersal ability, yet this assumption is not true for all anuran species. We suggest that future studies should include key behavioral traits, such as site fidelity and homing behavior, as these traits can represent the dispersal abilities of anurans and dispersal ability seems to be important when we try to predict patterns of anuran distribution.
AbstractAlthough chemical interactions play an essential role in lizard social behavior, the chemical composition of the femoral gland secretions that many lizards use for communication is known for only a few species, mainly European Lacertids. The tegu lizard, Salvator merianae, is the only species of the Teiidae family for which there is available information on lipids in femoral secretions, but only for captive bred males from Argentina. Here, based on mass spectra obtained by GC-MS, we found 69 lipophilic compounds in femoral gland secretions of wild males S. merianae from Brazil, including cholesterol and high amounts of saturated fatty acids (mainly hexadecanoic and octadecanoic). We found contrasting differences between wild and captive-bred males, which lack cholesterol but present high amount of 9,12-octadecadienoic acid. These within-species differences between wild and captive lizards strongly suggest the important influence of different diets on the chemical composition of the femoral gland secretion and suggest caution when interpreting results from captive animals, even in the same species.
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