Proposta de estudo sobre a osga-de-parede de S. Vicente, Tarentola substituta – a vida secreta das osgas
Environment thermal conditions, competition with conspecifics, or predator avoidance are conditioning factors in small ectotherms fitness. Among this species group, geckos stand out due to their key ecological role in food webs of arid habitats. Islands, especially arid ones, provide simplified systems of study, with scarcity of predators, lack of competitors and low habitat complexity. São Vicente is an arid island of the Cabo Verde Archipelago, and home of three endemic reptile species. The nocturnal gecko Tarentola substituta is the only that is widely distributed, presenting a high number of conspecifics, absence of competitors and low number of terrestrial predators. Since high diurnal temperatures pose thermal constrains to these animals, seeking refuge under rocks is necessary for thermoregulation. Previous studies found that lack of optimal refuges leads to intraspecific competition, with adults using the less abundant high-quality refuges and juveniles the low-quality ones. It was also found that refuges are mostly shared by a female-male pair, probably to reduce antagonistic interactions by males and to increase reproductive success of the pair, but further studies are needed to test this.
In order to determine the roles of ecological and social factors in refuge selection in T. substituta two experiments were designed: one in the lab of University of Cabo Verde (Uni-CV), and another in an arid area of island where only the species is present. The former experiment will use independent measures of solo and combinations of different age and sex classes of two individuals in a terrarium, allowing for the choice of four refuge options: high-/low-quality refuge close-/far from a heat source. In the latter experiment, six quadrates will be surveyed, for geckos (considering age, sex and aggregation type) and high-quality refuge availability. Then the density of those refuges will be manipulated to check if it will affect refuge choice of individuals.
Results will contribute to the understanding of refuge selection in T. substituta but will also shed light on the under-studied social behaviour of reptiles. Dissemination of the developed project in peer-reviewed journals and for the general public is also expected. Additionally, this project aims to further develop the link between Uni-CV and CIBIO, by involving Cabo Verdean students in the experiments and possibly in shared projects.
