Michael E. Rashotte - US grants

Two of the most significant threats to survival that animals face come from variation in the food supply and in the ambient temperature. Variations of both kinds are able to motivate major protective actions on the part of animals, including humans. Endothermic ("warm-blooded") animals can use several strategies that blunt the challenge posed by these environmental conditions. In particular, the endotherm can attempt to feed more efficiently, to improve the temperature of its surroundings, and to change the amount of heat lost from its body surface by varying its insulation and by adjusting its body temperature. Strategies of these sorts have been studied in some endotherms during periods of food scarcity and of cold ambient temperatures, but there has not been a suitable experimental situation in which to study the ways endotherms use these responses to maximal advantage by sequencing them or by combining them. Dr. Rashotte's research utilizes experimental procedures by which this problem can by studied. Pigeons are the endothermic animal chosen for study because of the large amount of separate information available on their feeding and thermal responses. The research uses computer technology to measure the feeding and thermal strategies of the birds in situations where the availability of food and the ambient temperature are varied. The work should result in a thorough description of how this endothermic animal copes with variations in the food supply and in cold ambient temperature. This information should be useful in understanding the survival strategies of birds and of endotherms in general, and it should provide a basis for investigating the neural and hormonal bases of survival in these environmental conditions.

9222369 Rashotte To survive in vastly different environmental conditions, such as occur across the seasons of a year, animals and humans must have good strategies for keeping their energy expenditure in balance with energy intake. Endothermic (warm-blooded) animals, including humans, face the most serious problem because of the need to maintain high body temperature and metabolic rate. This project will use advanced experimental methods to study in greater detail than has previously been possible the ways a very widely distributed and, in survival terms, highly successful endothermic animal (the pigeon) manages to cope with the range of environmental conditions in which it is found. By using unique computerized environments, this project will vary the ambient temperature, the difficulty associated with finding food, and the length of the daily light-dark cycle in ways that simulate some natural conditions for these animals. The experimental situation in which they live is highly instrumented to record their use of strategies for achieving energy balance through changing their feeding behavior, body temperature, metabolic rate, and overall daily activity level. In some cases, the environmental conditions are specifically designed to elucidate factors that influence which of these strategies are brought into play when the environment changes. This project is unique in providing new information about the changing interplay of these strategies across the animal's normal daily cycle of activity and inactivity, and in providing such data from animals which are free to adopt varied combinations of these strategies over the long term as they become acclimated to new environmental conditions. The outcome of this research is likely to deepen our knowledge of the survival strategies used by endothermic animals to cope successfully with varied environmental conditions. With the new and detailed information in hand which this project promises to provided, it shoul d be possible to encourage new lines of future research on specific brain and hormonal bases for these strategies. A thorough understanding of the relationship between changes in environmental conditions and the appearance of certain survival-related strategies involving feeding, metabolism, activity, and energy balance will contribute to basic knowledge in the life sciences and may ultimately have relevance for problems as diverse as the proper management of animal habitats and seasonally related human disorders involving metabolism and feeding.

Two laboratories interested in understanding cyclic physiological events related to different adaptive states of homeothermy will collaborate on comparative studies. Professor Michael E. Rashotte's laboratory in the Neuroscience Program at the Department of Psychology, Florida State University (Tallahassee, Florida, USA) and Professor Yuri F. Pastukhov's laboratory at the Sechenov Institute of Evolutionary Physiology and Biochemistry (St. Petersburg, Russia) are the participants. Each lab has extensive experience working on questions related to adaptive homeothermy, but one lab (Pastukhov) focuses on studies with mammals while the other lab (Rashotte) focuses on studies with an avian species. Their collaboration will provide each lab with the expertise to carry out comparative studies on the questions of interest using small mammals and avian species. The long-range objective is to make it possible for each lab to exploit species differences to answer fundamental questions about adaptive homeothermy.