| Abstract | dc.description.abstract | According to the “barrel model”, an organism
may be represented by a container, with input energy constraints
(foraging, digestion, and absorption) symbolized by
funnels connected in tandem, and energy outputs (maintenance,
growth, and reproduction) symbolized by a series of
spouts arranged in parallel. Animals can respond to changes
in environmental conditions, through adjustments in the
size of the funnels, the Xuid stored inside the barrel, or the
output Xow through the spouts. In the present study, we
investigate the interplay among these processes through the
analysis of seasonal changes in organ size and metabolic
rate in a lizard species (Liolaemus bellii) that inhabits
extremely seasonal environments in the Andes range. We
found that digestive organ size showed the greatest values
during spring and summer, that is, during the foraging seasons.
Energy reserves were larger during summer and
autumn, and then decreased through winter and spring,
which was correlated with overwintering maintenance and
reproductive costs. Standard metabolic rate was greater
during the high-activity seasons (spring and summer), but
this increase was only noticeable at higher environmental
temperatures. The ability of many lizard species to reduce
their maintenance cost during the cold months of the year,
beyond what is expected from temperature decrease, is probably related to their success in coping with highly Xuctuating
environments. Here, we demonstrate that this ability
is correlated with high physiological Xexibility, which
allows animals to adjust energy acquisition, storing and
expenditure processes according to current environmental
conditions. | en_US |
