Adaptations and resistance of zooplankton to stress: effects of genetic, environmental, and physiological factors.

The ability of a species to adapt to stress factors such as exposure to toxicants depends to a large extent on the presence of individuals that are able to respond to the exposure in a successful way. Several strategies can be employed to cope with different stress factors. Investments on growth and reproduction, for instance, can be varied to meet the requirements of the environment. Large individuals generally have a high resistance against stress, but a large body size is often achieved at the cost of other characteristics. In the present study, the resistance of several clones of Daphnia to different stress factors, such as toxic cyanobacteria, a predator released chemical, and starvation, was investigated. The focus was on interactions among different factors and whether observed responses can be regarded as evolved adaptations for the different conditions.