LIFE-HISTORY PATTERNS IN METAL-ADAPTED COLLEMBOLA

Life-history theory predicts that pollutants can be selective agents w hich mould life-history patterns. Pollution-mediated decreased adult s urvival and reproductive success was expected to induce earlier matura tion and an increased reproductive allocation per clutch. Divergence o f life-history patterns in relation to metal exposure was studied in r eference and metal-tolerant natural populations of the springtail spec ies Orchesella cincta. Mortality, growth and reproduction were analyse d in laboratory generation animals originating from six sites. The dos e-effect relationship for mortality was similar for all populations, e xcept for the control and the lowest exposure concentration. For anima ls from highly polluted sites, control mortality was higher than morta lity in the low exposed group. Inter-population differences with regar d to growth and reproduction were studied using two cadmium exposure l evels. Body growth was analysed using Von Bertalanffy' s growth model. Inter-population differences for asymptotic weight and growth rate we re small. Asymptotic weight depended on sex and treatment, growth rate also depended on population. Inter-population differences were highes t for post-hatching body weight. Juvenile body weight was highest and least affected by cadmium in animals from metal-contaminated sites. Fe male weight at first reproduction depended on population and exposure. Age at first reproduction was lowest in the most exposed populations. Clutch size differences were not found, but realized fertility was hi gher in exposed populations, since more clutches per female were produ ced. It is concluded that life-history patterns in 0. cincta differ be tween populations which have experienced a different duration and inte nsity of metal exposure. As the differences were found in laboratory g eneration animals, there is evidence for genetic differences between p opulations.