Ecologia de duas espécies de lagarto cogenéricas (Squamata, Tropidurus) em simpatria em uma área do semiárido no nordeste do Brasil

Abstract

Investigations regarding temporal, trophic and spatial niche dimensions of Brazilian lizards conducted in the chapter 1 of this study revealed that phylogenetically closely related species tended to overlap more intensely in the association with trophic and spatial resources, indicating that historical factors prevail over variations of environmental conditions among geographic regions in the determination of the ecology of each species. Throughout this study, I also analysed temporal (Chapter 2), trophic (Chapter 3), and spatial (Chapters 2 and 4) niche dimensions, ecomorphological associations (Chapter 5), parasitism (Chapter 6) and defensive behaviours (Chapter 7) of Tropidurus hispidus and of T. semiataeniatus living in sympatry on rock outcrops in northeastern Brazil. Differences in temporal niche dimensions were not the most relevant for the sympatric coexistence of T. hispidus and of T. semitaeniatus; however, these species differed substantially with regard to the utilization of the structural and thermal space, selecting microhabitats suitable for their physiological, ecological and behavioural requirements. These lizards might actively regulate their body temperatures through behaviour using air and substrate temperatures and direct sunlight. Tropidurus hispidus and T. semitaeniatus consumed similar types of food, mainly ants, termites, adult beetles, and flowers, but differed in sizes of food acquired. Tropidurus semitaeniatus lizards maintained high body temperatures to match with thermal requirements related with acquisition and digestion of food and had ontogenetic variations in consumption of vegetal matter, with the acquisition of plants increasing progressively with aging. Both species possess morphological characteristics that empowers lizards for utilization of different trophic and spatial resources. New records of occurrence of helminth species are reported for both lizard species: Piratuba digiticauda in T. hispidus and Oochoristica bresslaui in T. semitaeniatus. The parasitism by helminths may have caused physiological and behavioural reactions that promoted limitations in performances of lizards, resulting in decreasing of minimum flight initiation distances of T. hispidus and of body temperatures of T. semitaeniatus according with the increasing of abundance of parasites. Body dimensions of T. hispidus and of T. semitaeniatus influenced the occurrence of interspecific differences in defensive responses (immobility and minimum flight initiation distance) by these lizards and the body temperatures negatively affected the minimum flight initiation distances of T. hispidus causing constraints on locomotor performances. Morphology, ecology and behaviour of T. hispidus and of T. semitaeniatus acted in synergy enabling individuals for resource partition, helping to reduce overlaps in niche dimensions and favouring their coexistences in sympatry