Meeting Abstract
Organisms inhabiting characteristically unique environments match their life history traits to predictable environmental events associated with habitat variability. Thus, animals rely on cues such as change in annual photoperiod, rainfall, ambient temperature and other local factors to schedule life history stages (LHSs) such as reproduction and molt. These processes can be energetically costly, and may not be expressed simultaneously without negative effects on fitness. Rufous-collared sparrows (Zonotrichia capensis) living in valleys in the Atacama Desert –one of the most stable environments ever studied-, and in the semiarid Fray Jorge National Park in the north of Chile – extremely seasonal and unpredictable – offer ideal conditions in which to examine the interplay between androgens, glucocorticoids and thyroid hormone levels and their influence on life history trade-offs. Birds in the Atacama experiencing almost no seasonal environmental cues or constraints to organize the life cycle showed overlap of LHSs, low glucocorticoids, and low androgen levels year-round. In contrast, birds in Fray Jorge region facing dramatic predictable and unpredictable environmental changes showed strict temporal division of LHSs, higher glucocorticoids and cyclic levels of androgens across the year. How individuals integrate endocrine mechanisms and timing of LHSs can be pivotal to understand how birds will manage the dramatic increase in unpredictable events linked to climate change.
