Intergenerational trade-off for water may induce a mother-offspring conflict in favour of embryos in a viviparous snake

Parent-offspring conflicts are likely to occur when resources are limiting either at pre- or postnatal 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. 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. As a result of water deprivation, females became dehydrated, with the effects more pronounced in pregnant compared to non-reproductive females. Among pregnant females, the impa...