Professor Main is concerned with the total (behavioural, genetic, and physiological) adaptation of animals to aridity. He, and his graduate students, have investigated a wide array of animals with emphasis on frogs and marsupials. He combines a profound knowledge of natural history with a grasp of physiology and genetics which has led to significant and fruitful experiments. He has done distinguished and original work in the areas linking the established fields of behaviour, genetics and physiology.