Effects of sexual maturation and sex steroid hormone treatment on the temperature preference of the guppy, Poecilia reticulata (Peters)

Abstract

In a horizontal temperature gradient, male guppies prefer a significantly lower temperature (24.5 °C) than females (28.2 °C) or juveniles (28.1 °C). Treatment of juveniles and females with testosterone lowers their preferred temperature to that of males. The reduction in the preferred temperature of testosterone-treated juveniles can occur without the development of male secondary sexual characters. Estrogen treatment of juveniles is without effect, as is treatment of males with estrogen or testosterone. It is postulated that testosterone acts at the level of the hypothalamic thermoregulatory centre.