Comparative endocrinology, environment and global change.

All organisms respond to environmental cues that allow them to organize the timing and duration of life history stages that make up their life cycles. Superimposed on this predictable life cycle are unpredictable events that have the potential to be stressful. Environmental and social stresses have deleterious effects on life history stages such as migration, reproductive function and molt in vertebrates. Global climate change, human disturbance and endocrine disruption from pollutants are increasingly likely to pose additional stresses that could have a major impact on organisms. Such impacts have great relevance to conservation as well as basic biology. Although some populations of vertebrates temporarily resist environmental and social stresses, and breed successfully, many show varying decrees of failure sometimes resulting in marked population decline. Alternatively, many aspects of global change may not be overtly stressful but timing of life history events becomes out of step with phenology because pertinent environmental signals normally used have been changed. There is much we do not know about how organisms respond to their natural environment, particularly how salient signals are perceived and then transduced into neuroendocrine and endocrine secretions. Comparative endocrinology has a key role to play in resolving mechanisms underlying responses to the environment. In the face of increasing human disturbance and global climate change there is an urgent need for more integration of ecological, evolutionary and mechanistic studies on stress biology of organisms in their natural world.