Padrões de assimetria associados à ecologia de cinco espécies de lagartos tropicais Cnemidophorus (Squamata, Teiidae) em áreas de restinga ao longo da costa leste brasileira

Abstract

The study of developmental instability (DI) in organisms may be a useful tool to identify early signals of environmental stress. Variations in DI also influence the organisms fitness. The variation between the symmetry of the left and right sides, manifested as fluctuating asymmetry (FA), is widely used as a measure of DI. We screened the available scientific literature on asymmetry in reptiles and identified the following trends: environmental disturbances increase FA in populations, females tend to select males with symmetrical sexual traits, thermal instability during egg development can produce individuals with a higher asymmetry, occurrence of injuries is more frequent in asymmetrical individuals for a particular side, and there is a negative correlation between asymmetry and locomotor performance. There was no study on reptiles asymmetry at South America, considering our screening criteria. In this study, we used meristic and metrics bilateral traits to identify FA in populations of five species of Cnemidophorus lizards (C. abaetensis, C. lacertoides, C. littoralis, C. nativo, C. ocellifer) spread at 15 restinga areas along Brazilian east coast. The FA of individuals was higher at higher Cnemidophorus populations density, it was lower at restingas with higher environmental disturbance, and its relation to mercury concentration varied depending on the species. Probably the evaluated environmental stressors act with different intensities. The level of environmental disturbance and mercury concentration should cause earlier deterioration of individuals with higher FA. This results in an inverse relationship between these stressors and FA in populations. Individuals with autotomized tail had higher FA, which may indicate that individuals with lower fitness perform more tail autotomy than those with higher fitness. Lizards with tail autotomy also had higher body size, probably because older lizards have had more encounters with predator. We found no differentiation among species on tail autotomy frequency. Perhaps tail autotomy is better explained by environmental factors such as intensity of predation. The multiple traits FA indexes were more efficient than single traits index to compare individuals in different levels of environmental stress and to compare individuals with and without tail autotomy