Intergenerational trade-off for water may induce a mother-offspring conflict in favour of embryos in a viviparous snake
Résumé
1. Parent–offspring conflicts are likely to occur when resources are limiting either at pre- or
post-natal stages due to intergenerational trade-offs over resources. Current theory posits that
such conflicts may influence the evolution of parental allocation as well as reproductive modes.
While energy allocation to the offspring has received considerable attention, the distribution of
water – another potentially limited vital resource to both the mother and offspring – and the
resulting outcomes remain grossly understudied.
2. Here, we explored the intergenerational trade-off related to water resources in the viviparous
aspic viper (Vipera aspis) by examining the effects of water deprivation on female physiology
(body mass, haematocrit and osmolality), water transfer to developing embryos and
reproductive performance.
3. As a result of water deprivation, females became dehydrated, with the effects more pronounced
in pregnant compared to nonreproductive females. Among pregnant females,
the impacts of water deprivation on water balance were correlated with fecundity. In
contrast, water deprivation had no effect on water transfer to the offspring or on reproductive
performance.
4. Our results demonstrate that, under water-constraining conditions, female water balance is
compromised in favour of the developing embryos, highlighting a significant intergenerational
trade-off for water. Although ectothermic reptiles are particularly tolerant in water balance
perturbations, our results suggest that, like energy, water can be a conflicting resource
between mother and offspring. Parent–offspring conflict over water should therefore be
further investigated to better understand reproductive modes and reproductive trade-offs in
terrestrial organisms.