Amphibian larvae are highly susceptible to contamination, which can lead to lethal and sublethal effects. This impact can be measured by fluctuating asymmetry (FA), which is based on differences between the sides of organisms with bilateral symmetry. We evaluated the effect of acute and chronic exposure to Roundup Original Ò on Physalaemus cuvieri tadpoles. We measured tadpole survival and estimated the LC50 96h . We also evaluated whether a sublethal concentration increases the FA. In acute exposure, survival was reduced and the LC50 was 2.13 mg a.i./l. In chronic exposure, nostril-snout distance and eye width had a significantly higher FA in contaminated tadpoles. The chronic exposure to contaminants could lead to several sublethal effects, which would be used in biomonitoring surveys. Morphological traits affected by contaminants, such as malformations or FA, would be relatively more easily measured from field samples. Because it is cost effective, easy to measure, and can be obtained without tagging or housing field-caught animals, we suggest that FA is a promising marker for monitoring the environmental impacts of contaminants like Roundup. However, additional studies are necessary to understand what additional environmental stressors might impact FA, and how this might alter its utility for use in biomonitoring.
Phyllodytes Wagler 1830 is a genus composed of small species (SVL ranging 2.1–4.2 mm) that present odontoids and dwells in South America (Faivovich et al. 2005; Frost 2018). All known species of this genus are bromeligenous using bromeliads as shelter, calling site (males) and as egg deposition site (females). Offspring develops at the water retained in the axils (e.g., Bokermann 1966; Peixoto 1995; Haddad et al. 2013).
Agriculture and pasture activities are the main drivers for habitat reduction, directly affecting amphibian assemblages. In the Cerrado, the progress of agricultural and pasture areas negatively affects aquatic environments and their organisms, once the suppression of marginal vegetation reduces the natural protection against allochtone stressors. One possible way to measure the stress level is the Fluctuating Asymmetry (FA), which is calculated based on the deviations in the development of bilateral morphological traits of the organism. Herein, we evaluated whether environments with a higher degree of agropastoral influence and reduced marginal vegetation can increase FA levels in tadpoles of two common and widely distributed anuran species in the Cerrado (Physalaemus cuvieri and Scinax fuscomarginatus). We sampled and classified water bodies according to the percentage of agropastoral land use and marginal vegetation, and measured four morphological traits of tadpoles to evaluate the degree of FA. We found that in environments with intensive agropastoral land use, tadpoles of P. cuvieri and S. fuscomarginatus had higher FA in nostril-snout distance (NSD). In environments with reduced marginal vegetation, tadpoles of S. fuscomarginatus had higher FA in eye width (EW), but no effect was detected for tadpoles of P. cuvieri. These morphological traits (i.e. nostrils and eyes) are associated to individual fitness of tadpoles. Thus, these developmental deviations can affect species fitness and population homeostasis over time, contributing to generate stochastic population dynamics and increasing the vulnerability of native species to local extinctions. The use of FA as a tool to measure environmental impact on species with potential to be used as bioindicators can contribute to generate and test hypothesis when integrated with long-term studies.
Bokermannohyla (tribe Cophomantini) is an endemic genus of Brazilian treefrogs containing 32 species arranged into four phenetic groups. The B. pseudopseudis group includes nine species, which are typically found in rupestrian ecosystems of disjunct Brazilian mountain ranges. Tadpoles have been shown to be important sources of information for the taxonomy of this genus, although careful analyses of character variation and descriptions of internal anatomy remain scarce. Since the first description of B. pseudopseudis tadpoles was based on a mixed series containing specimens of B. pseudopseudis and B. sapiranga, we describe the larvae of these two species from their type localities, including their external morphology, oral cavity, and skeletal system. Tadpoles of B. pseudopseudis are easily distinguished from those of B. sapiranga by aspects of their coloration and characters of their oral disc (more labial tooth rows, more numerous submarginal papillae and flaps with labial teeth). These morphological differences may be diagnostic for these two similar species, whereas their chondrocranium, hyobranchial apparatus, and oral cavity are alike, suggesting less variability in these character systems between closely related species. Finally, we provide the first comparison of data on the skeletal system of Bokermannohyla and other Cophomantini, highlighting characters of potential relevance to the systematics of the tribe.
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