Cladoceran populations can respond to changing predation regimes by a phenotypical response as well as by shifts in genotype frequencies. In this study, we investigated the phenotypic plasticity exhibited by life history traits of D. galeata in response to the presence of predator kairomones, as well as the extent to which natural selection may act on these traits and their phenotypic plasticity. In a life-table experiment, seven clones of a natural D. galeata population were subjected to kairomones from fish (Perca), from an invertebrate predator (Chaoborus) or a mixture of both. Life history traits were affected by the kairomones of both predators, but effects of Chaoborus were neutralised by Perca in the kairomone mix. No apparent trade-off was found between growth-and reproduction related traits: although daphnids from the Chaoborus treatment grew faster than daphnids from the other treatments, no reduction in the reproductive output was observed. Broad-sense heritabilities were found to be relatively high for some life history traits (size at maturity, neonate size, number of neonates) as well as for the phenotypic plasticity response of these traits. This reflects the evolutionary potential of life history traits and their phenotypic response to predator kairomones in the D. galeata population. [KEYWORDS: broad-sense heritability; Chaoborus; Perca; kairomone mixture Invertebrate predators; zooplankton community; chaoborus; pulex; size; behavior; hyalina; shifts; magna; fish]
Original languageEnglish
Journal publication date1997

ID: 189134