Agropastoral activities increase fluctuating asymmetry in tadpoles of two neotropical anuran species

Abstract

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.

Drosophilid species (Insecta, Diptera) in the Brazilian savanna are more symmetric in the dry season

“…Likewise, specimens of Drosophila melanogaster developed under larval overpopulation were more asymmetrical than those developed under low density (Imasheva & Bubliy 2003). Neotropical tadpoles subjected to disturbed habitats were more asymmetric than those established in preserved environments (Costa et al 2017), and salmons from hatchery-origin were more asymmetric than wild salmon (Koeberle et al 2020).…”

Association between land use and composition of amphibian species in temperate Brazilian forest remnants

“…Most amphibians breed in aquatic sites, and changes in landscapes can restrain access to ponds or streams (Becker et al 2007, 2010; Machado et al 2012; Cayuela et al 2015; Saccol et al 2017; Dalmolin et al 2019). This can promote morphological and physiological changes in tadpoles and adults (Costa et al 2017) and reduce reproductive potential, causing changes in the communities’ structure and composition (Berriozabal-Islas et al 2018; Dalmolin et al 2020), as well as population declines or local extinctions (Marsh and Trenham 2001; Rothermel 2004; Goutte et al 2013). Therefore, amphibians are considered good models for ecological studies on understanding the impact of landscape changes on wildlife.…”

“…Therefore, amphibians are considered good models for ecological studies on understanding the impact of landscape changes on wildlife. The monitoring of amphibian populations has been filling the gaps in our understanding of how landscape changes affect species diversity (Becker et al 2007; Pillsbury and Miller 2008; Nomura et al 2011; Collins and Fahrig 2017) and the physiology and morphology of amphibians (Costa et al 2017; Berriozabal-Islas et al 2018). This highlights the importance of studies that include a greater variety of altered or natural habitats and conduct measurements in the surroundings of the sampled habitats.…”

Living in a changing world: effects of roads andPinusmonocultures on an anuran metacommunity in southern Brazil

“…The transformation of natural habitats into anthropogenic landscapes is considered one of the major threats to biodiversity in the 21 st century (Bitar et al, 2014). Habitat loss and fragmentation resulting from agriculture, monoculture forestry and urban expansion results in changes in the structure and functioning of ecosystems throughout the planet (Lion, Garda & Fonseca, 2014;Costa, Solé & Nomura, 2017;Berriozabal-Islas et al, 2018). At this present age, known as the Anthropocene, attention to the effects of anthropogenic changes on all levels and dimensions of biological diversity has become indispensable (Shanafelt et al, 2018).…”