Egg size and offspring fitness in a bdelloid rotifer

To test if the quality of offspring is affected by egg size and whether it increases with the amount of resources allocated to an individual egg, we c ompared the offspring hatched from small and large eggs of Macrotrachela qu adricornifera (Rotifera, Bdelloidea). Differently sized eggs were obtained by feeding mothers with different food concentrations. Large eggs were expe cted to provide better offspring in terms of (1) development time of the em bryos, (2) age at first reproduction of the juveniles and (3) recovery afte r desiccation of the newborns. The comparison between offspring hatched fro m large vs. small eggs of the same bdelloid species revealed that animals h atched from large eggs had shorter embryonic development and earlier age at first reproduction than animals hatched from small eggs. In contrast, the capacity to survive stress, like desiccation, was not affected by egg size. Thus, offspring hatched from larger eggs had shorter generation times, but were not favoured under harsh circumstances.