NATURAL HISTORY OF THE BLACK IGUANA Ctenosaura similis (SQUAMATA: IGUANIDAE) IN ISLA CONTOY, QUINTANA ROO, MEXICO

The genera Iguanaand Ctenosaurabelong to the Iguanidae family, and populations of most species of these genera have decreased due to anthropogenic effects. The natural history of most species of this family is poorly known, including Ctenosaura similis. Therefore, this study documents some ecological aspects of the species, such as its feeding habits, and habitat and microhabitat use in a population on Isla Contoy in Quintana Roo, Mexico. The data showed that even though C. similisis distributed throughout the island, individuals more commonly use human construction (buildings) of Parque Nacional Isla Contoy (PNIC) and mangrove areas. Microhabitats most used by all age classes and sexes were rocks and trees. The diet of the species is omnivorous; however, the frequency of prey type consumed changes with the age of the individuals (hatchlings, juveniles, and adults), as well as with the season of the year. The practice of cannibalism by some individuals is also reported, as well as coprophagy and scavenging. This work provides general information on the life history of C. similis, complementing the scarce information that is currently available.

Thermal biology in two syntopic lizards, Phymaturus extrilidus and Liolaemus parvus, in the Puna region of Argentina

Body temperature is the most important ecophysiological variable affecting reptiles' life history. Moreover, thermoregulation in ectotherms implies a struggle to reach preferred temperatures in natural conditions due to the influence of biotic and abiotic factors. Our objective was to evaluate and compare the thermal biology of two syntopic species, Phymaturus extrilidus and Liolaemus parvus, in the Puna region of San Juan, Argentina. We determined body temperature (T_b), micro-environmental temperatures (T_a and T_s) and operative temperatures (T_e) in the field. In the laboratory, we measured preferred temperatures (T_pref) and calculated the index of thermoregulatory efficiency (E). Neither body temperatures in the field nor preferred temperatures varied between seasons and sexes. Body temperatures were lower than preferred temperatures for both species. Nevertheless, regardless of the low thermal offer available in habitat, both species did achieve body temperatures higher than operative temperatures during activity. Thermoregulatory effectiveness was moderate in P. extrilidus (E=0.65), while L. parvus presented greater thermoregulatory efficiency (E=0.78). We conclude that under the rigorous climate conditions of the Puna, Phymaturus extrilidus and Liolaemus parvus are able to actively and efficiently thermoregulate, maintaining body temperatures close to the preferred and higher than those of its habitat. Differences in thermal characteristics between Phymaturus extrilidus and Liolaemus parvus are a consequence of differential limitations imposed on each species by the environment and of forces inherent to their life histories.