Estudos da comunidade de Squamata e de ecologia comportamental de Tropidurus Hispidus e T. Semitaeniatus (Squamata, Tropiduridae) em área de caatinga lato sensu

Abstract

The Caatinga occupies an area of approximately 800,000 km2, and is characterized by rainfall scarcity, high temperatures, and variability in climatic seasonality, with strong intercalation of dry and floody years. Among these phytophysiognomic and morphoclimatic aspects, it is worth noting that this area has at least two landscapes known in the literature: Caatinga stricto sensu and Caatinga lato sensu. The Caatinga stricto sensu refers to areas located in the Northern Country Depression (Depressão Sertaneja Setentrional), with shrubby vegetation and higher temperatures. On the other hand, the Caatinga lato sensu comprises areas of arboreal-bushy vegetation located on the tops of plateaus and mountains with more than 500 m altitude, thus presenting milder temperatures. Classical studies highlight the existence of a pattern of relictual distribution for some lizard species of the Caatingas, which seem to be unique from areas of Caatinga lato sensu. Four 20-day trips were carried to the study area, two in 2014 and two in 2015, in March (rainy season) and September (dry season). In 2014, Squamata specimens were registered and/ or collected through active search and pitfall traps, and for each active specimen, habitat, microhabitat and activity hour were recorded. In 2015, behavioral observations of tropidurid lizards were carried out through focal sessions to analyze the themoregulatory and foraging behaviors and compare them with populations of a Caatinga stricto sensu area. A total of 34 species of Squamata was recorded, and the rarefaction curve did not reach an asymptote, indicating the possibility of more species in the area. Noteworthy is the presence of species with relictual distributions, such as Acratosaura mentalis, Enyalius bibronii and Anotosaura vanzolinia. Comparing the composition of the lizard species with other Caatinga sites, we observed the formation of three groups: communities from forested highlands; from areas of Caatinga lato sensu, and from areas of Caatinga stricto sensu. A null model analysis showed that the studied lizard community is structured on the spatial niche axis, indicating a significant influence of contemporary ecological factors on this assemblage. The non-random use of space by the lizard species indicates the presence of competitive interactions that influence the selection of habitats and microhabitats used. In general, the two Tropidurus species did not differ in their thermoregulatory behavior, although T. semitaeniatus exposed yourself to the sun more than T. hispidus during the rainy season. Regarding the foraging behavior, T. hispidus and T. semitaeniatus behaved similarly in the dry season, changing strategy during the rainy season. The two species foraged more actively during the rainy season in the studied site when compared with an area of Caatinga stricto sensu. In conclusion, the data obtained in this study confirm the presence of relictual species and the presence of different behavioral strategies for tropidurid lizards in area of Caatinga lato sensu.