Revista Chilena de Historia Natural 81 (2): 171-178, 2008
RESEARCH ARTICLE
Intraspecific variation in a physiological thermoregulatory mechanism: the case of the lizard
Liolaemus tenuis (Liolaeminae)
The interspecific variation of heating rates in Liolaemus lizards, suggests an
adaptive value of this physiological thermoregulatory mechanism, which would allow lizards to cope with the environmental thermal
restrictions, imposed to behavioral thermoregulation. This trend has barely been tested at intraspecific level, and here we explore if
intraspecific variation in heating rates occurs in Liolaemus tenuis, a relative widely distributed species from central Chile.
We test the hypothesis that heating rates are related to the thermal environmental conditions at which populations are exposed, by
comparing the heating rates of three populations (from a latitudinal range), which inhabit under different thermal conditions. Additionally,
we explore if the intrinsic factor, sex, also modulates heating rates. There was a significant intraspecific variation in heating rates, at
population and gender level. These rates however, showed only a partial relationship with the environmental thermal conditions. We
found that the northern population, inhabiting at higher temperature, heated slower, which might reduce the risk of overheating. On the
other hand, independent of the population, females heated slower than males. The meaning of this sexual variation is unclear, but may
be consequence of the significant differences in genders’ social behavior. Because males defend a territory with a harem, by heating
faster, they can allocate extra time in behaviors associated to the defense and maintenance of the territory.
Key words:
Chile, geographic
variation, sexual variation, thermoregulation
