Family planning inDaphnia: resistance to starvation in offspring born to mothers grown at different food levels

Abstract

We observed a shift in maternal investment per offspring in clonal cultures of twoDaphnia species. Mothers grown at high food levels produced large clutches of smaller eggs but their offspring could not survive long under starvation conditions. Genetically identical mothers grown at low food levels produced small cultches of larger eggs, and their offspring, albeit low in numbers, were able to survive long periods of starvation. Our data show thatDaphnia mothers are capable of assessing food level and use this information in adjusting their fractional peroffspring allocation of reproductive resources.

Reproduction as one of the main causes of temporal variability in the elemental composition of zooplankton

“…However, most adult females survived below the ice cover, waiting to reproduce until the next ice-free period. A similar behavior has been described for the same species in an alpine lake in the Tatra mountains (Gliwicz et al 2001), with the difference that males were always absent in the Tatras lake. Cyclops adults also survived below the ice cover, probably synchronizing its life cycle with the Daphnia, as the former prey on the latter (Gliwicz et al 2001).…”

“…A similar behavior has been described for the same species in an alpine lake in the Tatra mountains (Gliwicz et al 2001), with the difference that males were always absent in the Tatras lake. Cyclops adults also survived below the ice cover, probably synchronizing its life cycle with the Daphnia, as the former prey on the latter (Gliwicz et al 2001). However, unlike in other northern European lakes (Nilssen and Elgmork 1977), the Cyclops population of Lake Redon has up to now not been observed to overwinter as copepodites in the sediments.…”

“…6), whereas that of the other two species decreased. Because the P content of Daphnia is almost twice as high as that of Cyclops, even occasional predation by the latter on the former (Gliwicz 1994) will ensure an excellent P source without any need for storage over the winter. A certain synchronization of the (Gliwicz et al 2001).…”

“…Because the P content of Daphnia is almost twice as high as that of Cyclops, even occasional predation by the latter on the former (Gliwicz 1994) will ensure an excellent P source without any need for storage over the winter. A certain synchronization of the (Gliwicz et al 2001). Whatever the dependence of Cyclops on Daphnia for P, our results provide field evidence that some species store P for later offspring production in addition to storage of energy compounds.…”

“…In both habitats, female embryo development started well in advance of the production maxima, which allowed the young stages to grow during the productive periods. Because they are smaller and have high energy demands for development, the young stages are usually less resistant to starvation (Gliwicz and Guisande 1992). Therefore, this strategy is an adaptation enabling survival in these low food environments.…”