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Igor Luis Kaefer and Albertina Pimentel Lima

Abstract

Because of its close relationship with the process of evolutionary differentiation, it is expected that geographic variability in acoustic sexual traits should be greater among than within populations. This is particularly expected in organisms with typically high population genetic structure and low dispersal abilities, such as anuran amphibians. We studied the acoustic traits of the advertisement call in the small-sized dendrobatoid frog Allobates paleovarzensisthrough its range in Central Amazonia. We accessed the variability of call traits from the within-male to the among-population levels, and evaluated the degree of stereotypy of the call characteristics. Call variability had comparable magnitudes within and among populations, and was independent of the degree of stereotypy of call measurements. Therefore, none of the call traits stood out as a potential cue for discrimination between populations. Spectral call measurements were static and strongly related with body size, which explained between 30 and 35% of the variation of these acoustic traits. Temporal characters of the notes were dynamic and influenced by environmental temperature (e.g., 27% of note rate variation), whilst temporal measurements of the entire calls were not related to the co-factors analysed. Both spectral and temporal call traits varied among populations and between sides of the Amazon River. Our results also indicate that body size and sampling site jointly affected the variability of the call traits. However, geographic distances among populations and the river barrier had no significant effect on the overall acoustic variation, indicating that local stabilising selective forces may be important in the process of call differentiation.

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Ana Carolina Mello, Luciana Erdtmann, Pedro Simões and Albertina Lima

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Niro Higuchi, Albertina Lima and Fernando I.O. Suárez

Abstract

We evaluated the effect of experimental logging of two different ages, and the effect of tree girdling without selective logging, on the local abundance of three heliothermic lizards. The response to intensity of selective logging varied among species of lizards. The local abundance of M. nigropunctata increased with the intensity of logging damage, while the relationships for K. calcarata and A. ameiva were not statistically significant. The three species used plots cut four years before more frequently than control plots, but the density of A. ameiva in gaps in blocks cut 9-10 years before was similar to that in undisturbed vegetation. The girdling treatments had a significant negative effect on K. calcarata, but not M. nigropunctata or A. ameiva. We suggest that differences in numbers of lizards reflect a behavioral choice for microhabitats created in the logging areas, because the spatial scale of this study was too small to confidently detect the effects of the silvicuture treatments on populations of the species.

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Diana Patricia Rojas, Adam Stow, Adolfo Amézquita, Pedro Ivo Simões and Albertina Pimentel Lima

Aposematic colouration deters visually oriented predators because conspicuous signals are easier to detect and associate with unpalatability. Consequently, brightly coloured prey that are novel are predicted to be preyed on more than those with bright but typical colours. Here we evaluated whether predatory bias is associated with the colour differences observed at two different localities for a large, conspicuously coloured and poisonous Amazonian frog, Adelphobates galactonotus. At each locality predation experiments were carried out using frog models of two naturally occurring colours of the study species (blue and orange) and a control (brown). We found no evidence that novel colours were more vulnerable to predation than local colours. These results do not therefore support our hypothesis that predatory bias explains the geographic variation of colour in A. galactonotus.

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Ana L.K. Albernaz, Selvino Neckel-Oliveira, William Magnusson and Albertina Lima

Abstract

We studied the distribution of anurans in savanna, regrowth and mature forest at the mouth of the Tapajós river in Brazilian Amazonia. We sampled 31 sites on the right bank of the Tapajós river and on the shores of lakes nearby, and recorded all acoustic and visual observations of frogs. We found 18 anuran species: Leptodactylidae (8), Hylidae (7), Bufonidae (2) and Pseudidae (1). The distribution of species indicated that some species are generalists and others are restricted to certain habitats. The species at Alter do Chão are a subset of those found in forested sites in Amazonia. Lakes and forested areas had the greatest anuran diversity, but are also the areas most disturbed by tourist development and agriculture. Reduction of anuran diversity in the area could be minimized by concentrating development along the main beaches of the Tapajós river.