A stress response in someAntechinus stuartii (Macleay)

Abstract

The adrenocortical activity of individual A, stuartii from a natural population was assessed by measuring the concentration of corticosteroids, glucose, sodium, and potassium in the plasma, and of glycogen in the liver; also by weighing the adrenal glands and measuring the cross-sectional areas of the zones in them. Changes in these parameters, detected by a comparison of samples of individuals drawn from the population at different times during the life history, demonstrate a stress response among males when survival is lowest. All males died after mating; immediately before this there was an increase in the concentration of corticosteroids in the plasma and of glycogen in the liver, in the weight of the adrenal glands, and in the cross-sectional area of the zona fasciculata; lipid disappeared from this zone. There was a simultaneous decrease in body weight and in the sodium concentration in plasma. Individual males were hypoglycaemic. There was no conspicuous mortality among laboratory-held males or among females in natural populations at this time, and these animals did not exhibit this syndrome. Although these data provide evidence for a stress response among male A. stuartii in a natural population immediately before they all die, there is no evidence that this syndrome is a causal factor in this mortality.