Phenotypic plasticity induced using high ambient temperature during embryogenesis in domesticated zebrafish, Danio rerio.

Ambient temperature during early stages of life has a substantial effect on physiological processes, eliciting phenotypic plasticity during zebrafish developmental stages. Zebrafish are known to possess a noteworthy ability to modify their phenotype in dependence of environmental factors. However, there is a poor understanding of the effects of temperature during embryogenesis, which influences the biological function like survival ability and masculinization in later life. Since the middle embryonic phase (pharyngula period) is genetically the most conserved stage in embryogenesis, it is very susceptible to embryonic lethality in developmental processes of vertebrates. Here we tested the effect of transient perturbations (heat shock) during early development (5-24 hours post fertilization; hpf) at 35°C compare to control group at 28°C, on survival ability of zebrafish to study the embryonic and post-embryonic mortality. We studied the variation of heat-induced masculinization among and across the families in response to high temperature. Furthermore morphometric traits of adult zebrafish at different developmental time points were measured in order to estimate the temperature × sex interaction effect. We found the highest embryonic mortality around the gastrula and segmentation periods in both experimental groups, with significantly lower survival ability in the temperature-treated group (73.30% ± 0.58% vs. 70.19% ± 0.57%, respectively). A higher hatching success was observed in the control group (71.08% ± 0.61%) compared to the heat-induced group (67.95% ± 0.60%). A distinct reduction of survival ability was also observed in both experimental groups during the first two weeks after hatching, followed by a reduced level of changes thereafter. We found sex ratio imbalances across all families, with 25.2% more males under temperature treatment. Our study on growth performance has shown a positive effect of increased temperature on growth plasticity, with a greater impact on female fish in response to high ambient temperature. This article is protected by copyright. All rights reserved.