Life history patterns of parental and hybridDaphniadiffer between lakes.

1. We investigated whetherDaphnia galeata × hyalinahybrids of Lake Constance and Lake Greifensee show the same pattern of life history parameters as previously reported forD. galeata × cucullatahybrids and whether such a pattern is consistent betweenDaphniapopulations from those two lakes.2. Hybrids in Lake Constance were intermediate in size compared with the parental species. Hybrids in Lake Greifensee were smaller thanD. galeata. The intrinsic growth rate (r) of hybrids from Lake Constance was not significantly different from the faster growing parental taxonD. galeata. However,rof hybrids from Lake Greifensee was significantly lower than that ofD. galeata.3. The observed juvenile body length differences between the taxa varied with the clutch number. The first clutch juvenile lengths of the three taxa did not differ for Lake Constance. First clutch juveniles of Lake GreifenseeD. galeatawere smaller than hybrid first clutch juveniles. The third clutch juvenile length did not differ between taxa from Lake Greifensee, butD. galeatajuveniles from Lake Constance were bigger than those ofD. hyalina.4. The life history pattern found in Lake Constance corresponds to previous findings from other studies. The hybrids in this lake combine the faster population growth of one parental species with a relatively small size. In the case of Lake Greifensee hybrids, the relatively large size of first clutch juveniles and the small size of the adults could be interpreted as dual adaptations to invertebrate and fish predation. We speculate that the lower population growth rate of the hybrids is a trade-off for this twofold protection. [ABSTRACT FROM AUTHOR]