The morphological and life-history data of two Daphnia species under different fish kairomone concentrations

Daphnia species can avoid predation by sensing fish kairomones
and producing inducible defenses by altering the phenotype. However, the
inducible response mechanisms of different Daphnia species to
fish kairomones remain unclear. In this study, the
morphological and life history strategy of two
Daphnia species (Daphnia pulex and Daphnia sinensis)
exposed to Aristichthys nobilis kairomones were studied. 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 shorter 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
inducible mechanisms (e.g., relative tail spine length, age at maturity,
and total offspring number) of the two Daphnia species exposed to
fish kairomones differ significantly and that the maternal morphological
traits can be transferred to the offspring such that they can avoid
predation.