Ecologia geografica de Tropidurus torquatus (Squamata : Tropiduridae) em areas de restinga da costa sudeste e sul-nordeste do Brasil : aspectos reprodutivos, ecologia termica e comunidades de nematodeos associados

AUTOR(ES)
DATA DE PUBLICAÇÃO

2003

RESUMO

Studies of geographical ecology can detect variation in a species ecological attributes along its geographical range, and determine the extent to which historical factors and/or local environmental factors can explain such variations. The wide geographic distribution of the tropidurid lizard Tropidurus torquatus makes it a good model for geographical ecology studies. In the present work three ecological aspects (reproductive traits, thermal ecology and parasite ecology) of T. torquatus were investigated in 10 populations of "restinga" (coastal sand dune) habitats along the coast of the states of Rio de Janeiro, Espírito Santo and Bahia. The minimum size at maturity of the females of T. torquatus was similar in all studied populations, although the mean body size varied. Mean c1utch size was low and showed little variation. The c1utch usually contained two eggs, most1y independent of female body size. Egg size was determined by female body size and showed marked interpopulational variation. 1n almost all populations of T. torquatus studied, females produced more than one c1utch during each reproductive season. Sexual dimorphism in size occurred in all populations and, except for the Maricá restinga, in head size as well. Geographical variation in c1utch and egg size can be explained by phylogenetic factors (body size), but local environmental factors (habitat structure and c1imatic conditions) seem to influence some ecological attributes such as c1utch size. Coastal populations of T. torquatus have a smaller body size than inland and insular populations, resulting in differences in many life history characteristics and suggesting that these coastal populations could make up a single group within the species. The mean body temperature of activity of the coastal T. torquatus populations was similar to those of other conspecific populations. The environmental temperatures (substrate and air) together influenced lizard body temperature, but their relative importance varied among the different populations as a consequence of the local c1imatic conditions. In most of the populations, air temperature was the main source of heat for the lizards. Active thermoregulation was recorded for several populations studied: as the environmental temperature increases, the lizards tend to thermoregulate more actively to avoid overheating. The conservative phylogenetic hypothesis was confirmed for the coastal populations of T. torquatus: the body temperatures in activity tend to remain constant along the geographic distribution of the species, and the differences observed result from the influence of environmental temperatures. At least eight helminth species were recorded in the community infecting T. torquatus in coastal populations. Considering only the nematodes, four species were considered "core" (P. lutzi, P. retusa, S. oscari and P. sceleratus), three were secondary species (P. venancioi, S. lacertilia and S. intermedia) and one resulted from accidental infection (H. boddaertii). The composition of the helminth community varied little as the core species were common in all or almost alllizard populations. The main geographical variation occurred in the structure of the helminth community as the abundance of the parasite species varied along the T. torquatus coastal populations. Lizard body size had a strong influence over nematode richness and helminth infection in all populations. Compared with other lizard species, T. torquatus has a rich and complex helminth fauna and seems to be a key host species for the coastal restinga parasite community harboured by it and other sympatric lizards, since it helps to maintain the richness and structure of the helminth communities

ASSUNTO(S)

reptil parasitismo lagarto

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