Thermo-physiological and growth responses of Liolaemus pictus argentinus to altitudinal environmental constraints

GUTIÉRREZ, J., IBARGUENGOYTIA N. R.

San Carlos de Bariloche

Congreso; VI Southen Connection Congress; 2010

Many reptiles that live in cold environments limit their activity due to their long periods of hibernation which increases along with latitude and altitude, affecting daily and seasonal activity periods, body temperatures and growth. In this study, the thermo-physiological responses, growth, age, longevity, and fecundity of two populations of Liolaemus pictus argentinus, from the same latitude in Bariloche, but different altitudes:  Challhuaco Mountain (1615-1769 m asl) and Melipal beach (771 m asl) were compared. The Challhuaco population had lower body temperatures (Tb = 29ºC) than the Melipal population (33ºC), while preferred temperatures (TP) were similar (TP, Challhuaco=36.7; TP, Melipal=36.6). The index of effectiveness of the thermoregulation (E) showed that L. p. argentinus in the Challhuaco behaved as a moderate thermoregulator (E = 0.4), while in the Melipal population behaved as a moderate thermoconformer (E = -0.24) .Both populations were able to maintain similar growth ratesand longevity by means of thermoregulation, showing the plasticity of this species to adapt to different environments. The only differences found corresponded to a broader age range at sexual maturity in Challhuaco (3 – 6 years) and lower longevity (8 years). In Melipal, instead sexual maturity was achieved at 4 years, with a lifespan of 9 years resulting in higher fecundity (11.25). Irrespective of age, the minimum body size shows to be the main factor in the acquisition of sexual maturity.