Parenting is costly and because the relationship between the mother and embryos is not mutualistic, mother–offspring conflicts may exist whenever resource are scarce. However, intergenerational trade‐offs and conflicts resulting from limited access to water, a vital and depreciable resource, remain largely overlooked. In this study, we examined the physiological, reproductive and life‐history responses to water restriction in the European Common Lizard (Zootoca vivipara). We hypothesized that, under water‐limited conditions, pregnant females experience both short‐term and long‐term physiological impacts (dehydration and stress) underlying an allocation trade‐off for water between mothers and offspring. Water restriction led to a decrease in body mass, and an increase in plasma osmolality (dehydration) and corticosterone concentration in both males and females. The extent of the dehydration was positively correlated with fecundity in females. This suggests a trade‐off between maternal water balance and allocation of water to developing embryos during reproduction. Water restriction had no immediate effect on reproductive output or offspring morphology at birth. Yet, water restriction in pregnant females enhanced their reproductive effort the following year but reduced the early life growth and annual survival of their second‐year offspring. These delayed fitness responses to water restriction in offspring and mothers suggest that water can trigger intergenerational conflicts as demonstrated for energy. Although the mediation of this conflict remains to be clarified, we hypothesized that it represents a selective force that influences reproductive strategies. A http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.13009/suppinfo is available for this article.

Immune responsiveness, one measure of individual quality, can be used as a sensitive, non-lethal variable that may be negatively affected in animals exposed to degraded, contaminated or otherwise disturbed areas. One frequently used technique to measure immune responsiveness is the phytohaemagglutinin (PHA) challenge test. Swelling occurring at the injection sites are measured before and 24 h after PHA injection. The immune response is considered to be the difference between the two measures. Although this method is easily performed with wild animals, it has been rarely used on small amphibians. Here, we test the possibility of using a PHA test with the European tree frog, Hyla arborea, and we identify the optimal procedure for measuring immune responsiveness in this species. The results allowed us to simplify the procedure in eliminating phosphate-buffered saline (PBS) injection and reducing the duration of the experiment. Injection of PHA into the leg of H. arborea triggered an immune response with a peak of swelling 14 h after injection. A second injection of PHA into the same animal induced more intense leg swelling. In addition, haematological responses showed that the total number of leucocytes increased after PHA injection. A link between the leg swelling and the total leucocytes count recorded in blood has been found. Consequently, this method may provide a useful tool for predicting the pro-inflammatory capacity of field populations of small amphibians.

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