Trade-offs in rotifer diapausing egg traits: survival, hatching, and lipid content

Abstract

The production of diapausing eggs is an ecological strategy commonly used by zooplanktonic organisms to cope with adverse conditions in time-varying habitats. Traits related to diapause (e.g., the time spent in diapause, the hatching fraction of diapausing eggs, or the amount of reserves allocated to them) should be combined by natural selection to favor adaptation to particular habitat conditions, especially in relation to their hydrology. Indeed, trade-offs between these traits are likely to occur due to resource allocation. Here, we studied population differentiation in survival, hatching propensity, and the amount of lipid reserves stored in diapausing eggs of the rotifer Brachionus plicatilis. We studied populations from ponds varying in hydrological conditions and used pond area as a proxy of water permanence. We found differences among B. plicatilis populations in the three traits studied, but no relationship with pond area. A significant negative relationship between diapausing egg survival in the sediment and hatching fraction was observed. We also found a negative relationship between lipid content and survival. These trade-offs are discussed in relation to the risks experienced by the rotifers in a given habitat, their ability for long-term survival, and the potential to disperse and recolonize new habitats.