Thermally induced plasticity of body shape in adult zebrafish Danio rerio (Hamilton, 1822).

We examined the effect of temperature during the early development on the phenotypic plasticity of Danio rerio. The effect of temperature was examined during two different early developmental periods of 280°d (the product of days × temperature) each, 28-308°d or 280-560°d, by subjecting the experimental populations to three different water temperatures (22°C, 28°C, and 32°C). Before and after the end of the 280°d period of the different thermal exposure, all populations were cultured in standard temperature (28°C). Five to 10 months after exposure to the different thermal regimes, the body shape of the adults was analyzed by geometric morphometrics. In both ontogenetic windows and experimental repetitions, the results showed that developmental temperature and sex significantly affected the body shape of adult zebrafish. Thermally induced shape variation discriminated the fish that developed at 22°C from those developed at 28°C-32°C. In the early developmental period (DP1, 28-308°d postfertilization), dorsal, anal, and caudal fin structures differed between the animals that developed at 22°C and 28°C-32°C. In the later developmental period (DP2, 280-560°d postfertilization), caudal, anal, pectoral, and pelvic fins, as well as the gill cover and lower jaw, were affected when animals developed at different temperatures. These results show that thermal history during a short period of embryonic and larval life affects the body form of adult zebrafish with potentially functional consequences. Based on previous data on the effects of temperature on fish development, we suggest thermally induced muscle and bone remodelling as possible mechanism underlying the observed plasticity.