Abstract
1. To evaluate the adaptive effects of prenatal temperatures, guppies borne by 23°C- and 28°C-acclimated parents were reared at 23°, 28°, 30°, or 32°C, and secondary sex differentiation, mortality, and vertebral column abnormality were observed.
2. Both mortality and the occurrence of vertebral column abnormality increased as the postnatal temperature rises. The rate of secondary sex differentiation was higher in order of 30°, 32°, 28°, and 23°C of postnatal temperature.
3. In fish borne by 23°C-acclimated parents, mortality at 30° and 32°C and vertebral column abnormality at 30°C were larger and the rate of secondary sex differentiation was always higher in comparison with fish borne by 28°C-acclimated parents.
4. Thus, the prenatal temperature is considered to affect more or less adaptively the tolerance of fish to high postnatal temperatures.
