Ref ID : 7025
Jan E. Kammenga and Joost A.G. Riksen; Comparing Differences in Species Sensitivity to Toxicants: Phenotypic Plasticity versus Concentration-Response Relationships. Environmental Toxicology & Chemistry 15(9):1649-1653, 1996
Reprint
In File
Notes
The comparison of species sensitivity to toxicants is classically derived from differences in the concentration-response relationships of a sensitive trait such as reproduction. We tested this general concept by conceiving the concentration-response relationship as a plastic response to a range of discrete environments. Using a demographic model based on life-cycle experiments for two nematode species (Plectus acuminatus and Heterocephalobus pauciannulatus) we related copper-induced plasticity in reproduction to changes in fitness, which was defined as the population growth rate. Daily reproduction (n(t)) in P. acuminatus was more sensitive to copper (EC20=48 µM) than in H. pauciannulatus (EC20=138 µM). However, the relationship between plasticity in n(t) and fitness showed that for both species, fitness was reduced with 5%. These findings imply that P. acuminatus and H. pauciannulatus are equally susceptible to toxicant-induced changes in n(t) despite their differences in EC20 values for reproduction. It may be concluded that differences in susceptibility of species to toxicants are not only determined by the effect on sensitive traits but also by the relationship between plasticity in this trait and fitness.