| Abstract | dc.description.abstract | Our planet is undergoing fast environmental changes,which are referred as global change. In this newscenario, it
is of paramount relevance to understand the mechanistic basis of animal responses to environmental change.
Here we analyze towhat extent seasonal changes in the digestive function of the lizard Liolaemusmoradoensis is
under endogenous (i.e., hard wired) or exogenous (i.e., environmentally determined) control. For this purpose
we compared animals collected in the field during autumn, winter and summer, against (experimental)
specimens collected in the field at the beginning of autumn and reared in the laboratory under simulated summer
conditions until winter. We found that different aspects of the digestive function are under different types of
control: small intestine length appears to be under endogenous control (i.e., experimental animalswere similar to
winter animals), small intestine mass appears to be under exogenous control (i.e., experimental animals were
similar to summer animals), and specific enzyme activities did not change throughout the year. Thus,we suspect
that processes related with gut length, such as cell division, may be under endogenous control, while others
relatedwith gut mass, such as enterocyte size and content, may be determined by exogenous factors, such as the
presence of food in the intestinal lumen. Faced with accelerated changing conditions, the ability of vertebrates to
cope will be closely related with their plasticity infitness-associated traits.More studies aimed at determining the
levels and limits of physiological flexibility will be necessary to understand this phenomenon. | es_CL |
