Morphological and life‐history trait plasticity of two Daphnia species induced by fish kairomones

Abstract

Abstract Daphnia can avoid predation by sensing fish kairomones and producing inducible defenses by altering the phenotype. In this study, the results showed that the morphological and life‐history strategies of two Daphnia species (Daphnia pulex and Daphnia sinensis) exposed to Aristichthys nobilis kairomones. In the presence of fish kairomones, the two Daphnia species exhibited significantly smaller body length at maturity, smaller body length of offspring at the 10th instar, and longer relative tail spine of offspring. Nevertheless, other morphological and life‐history traits of the two Daphnia species differed. D. pulex showed a significantly longer relative tail spine length and earlier age at maturity after exposure to fish kairomones. The total offspring number of D. sinensis exposed to fish kairomones was significantly higher than that of the control group, whereas that of D. pulex was significantly lower. These results suggest that the two Daphnia species have different inducible defense strategies (e.g., morphological and life‐history traits) during prolonged exposure to A. nobilis kairomones, and their offspring also develop morphological defenses to avoid predation. It will provide reference for further exploring the adaptive evolution of Daphnia morphology and life‐history traits in the presence of planktivorous fish.

Keywords

• Aristichthys nobilis
• Daphnia
• inducible defenses
• kairomone
• phenotypic plasticity