Abstract: Developmental plasticity is a key factor driving the evolution and diversification of new traits. Under the context of climate change, exploring the developmental plasticity of fish thermal adaptation is helpful for understanding the evolution of fish thermal adaptation phenotype in the early stage of their life history. To examine the effects of embryonic and newly hatched larval development temperatures on thermal adaptability of fish, we carried out an experiment following factorial design, in which both embryos and newly hatched larvae were reared in a low (22 ℃) or a high (28 ℃) temperature. Zebrafish (Danio rerio), a small oviparous fish, was used an animal model. The effects of incubation temperature of embryos and development of newly hatched larvae and their interactions on thermal adaptation phenotypes, including preferred temperature, avoidance temperature (including cold avoidance temperature and heat avoidance temperature), non-avoidable temperature range, and thermal tolerance (including critical thermal minima, critical thermal maxima, lethal thermal minima and lethal thermal maxima) of zebrafish larvae were investigated. The results showed that both incubation temperature of embryos and development of newly hatched larvae had a significant impact on the preferred temperature, avoidance temperature, and thermal tolerance (P<0.05). Moreover, the interaction of embryonic and newly hatched larval development temperature had a significant impact on non-avoidable temperature range (P<0.05). The results suggest that the thermal environment of embryo incubation plays an important role in shaping the thermal adaptation phenotypes of zebrafish in the early stage of life history. The variations of developmental temperature may expand the suitable temperature range of fish, and thus improve their viability under the scenarios of climate change.

Key words: temperature, early development, phenotypic plasticity, thermal adaptation, zebrafish.