Starvation tolerance of rotifers produced from parthenogenetic eggs and from diapausing eggs: A life table approach

Abstract

Monogonont rotifers have to cope with environmental variation by producing diapausing stages. Cyclically, parthenogenetic rotifers produce females by (i) parthenogenetic eggs and (ii) sexually produced eggs. Parthenogenetic eggs hatch shortly after ovoposition, frequently while they are carried by their mothers. Sexual eggs go into dormancy and hatch in the sediment, in response to specific environmental cues. Therefore, it is expected that post-diapause and parthenogenetic offspring would face different environments. Moreover, resource allocation is higher in diapausing eggs than in parthenogenetic eggs. In this study, the response to starvation of females obtained from parthenogenetic eggs and from diapausing eggs of the rotifer Brachionus plicatilis was compared. Starved individuals showed unexpectedly long maximum longevity (∼12 days). The average lifespan and the lifespan variance of individuals hatched from parthenogenetic eggs were higher than those of individuals hatched from diapausing eggs. Contrasting with a previous experimental finding, our results do not support the hypothesis that high resource allocation in diapausing eggs causes high starvation tolerance. Lower survival of individuals hatched from diapausing eggs could be caused by the diversion of energy to other functions (i.e. maintenance during diapause or the hatching event), or the result of the variance in the allocation of resources in parthenogenetic eggs. We hypothesize that resource allocation in diapausing eggs follows a conservative pattern, while it is more opportunistic in parthenogenetic eggs. © The Author 2005. Published by Oxford University Press. All rights reserved.