Sustainability assessment of a lizard assemblage in Pernambuco state, Brazil

Abstract

Several species of lizards are disappearing around the world. Their populations are declining on a global scale and for carrying out conservation actions, it is necessary to identify the real risks of extinction and the threats that affect the species. Alternative methodologies that are commonly applied and also the use of different approaches are important tools to fill gaps concerning various threats and vulnerabilities of the species. The aim of this study was to test the effectiveness of the “Stobutzki sustainability” method in assessing the degree of vulnerability to extinction of lizards with occurrence registered in Pernambuco, Brazil. 41 species were evaluated by using the “Stobutzki sustainability” method, based on scoring and ranking. The analysis was made from a graphical representation of the factors of "Threats" and "Vulnerabilities" of lizards. The great majority of the species (n = 30) has not shown to be vulnerable. Only 11 lizards were not considered sustainable. The lizards Nothobachia ablephara, Cercosaura ocellata, and Procellosaurinus erythrocercus demonstrated a very high degree of vulnerability to extinction. The gymnophtalmidae family was the least sustainable. A total of 16 threats of anthropogenic origin for the populations of lizards in Pernambuco were detected. Half of the species of lizards (n = 21) have a low number of embryos per litter (<3). Additionaly, this group was considered partially generalist, having an occurrence extension smaller than 40,000 km² and measurements between 100 and 300 mm in total length. Among the top 10 in our Vulnerability Ranking there are six lizards included in threat categories on the list of the Regional Environment Agency of Pernambuco. The "Vulnerabilities" axis was ordered by the fecundity of the species, their distribution and preference for certain microhabitats. Furthermore, for the "Threats" axis, the structuring was based on the situation of the habitats of these species and their distribution in protected areas. The strongest biological predictors of extinction risk for lizards of Pernambuco state were litter size, microenvironmental specificity, and the extent of occurrence. The “Stobutzki Sustainability” method is an important tool to assist the evaluation of vulnerability to extinction in lizard species, as well as the criteria used for researches on other lizard assemblages.