Growth and age of the southernmost distributed gecko of the world (Homonota darwini) studied by skeletochronology

Homonota darwini is the southernmost distributed gekkonid species of the world, as it can be found in South America from 35 degrees to 52 degrees S. Age and growth of H. darwini were studied using skeletochronology on diaphyseal femoral cross-sections. Individual ages were assessed after estimating the resorbed rings in relation to snout-vent length (SVL). SVL and age showed a sigmoidal relationship and growth rates showed a shift from premature growth to mature breeding when sexual maturity is achieved. The model indicates that sexual maturity in H. darwini is reached at five years in females and nine in males. Species longevity is estimated to be 17 years, which corresponds to a k-selected trait of late maturity and long life expectancy. Once sexual maturity is achieved, size is a poor indicator of age in this species. These results are discussed in terms of behavioural and physiological adaptations of this species to the strong environmental pressures of the Patagonian steppe. Our results also support the hypothesis that daytime burrow temperatures, which are similar to body temperatures recorded in diurnal lizard species, meet the physiological growth requirements of nocturnal lizard species.