Testing historical phylogeographic inferences with contemporary gene flow data: population genetic structure of the Qinghai toad-headed lizard

Life history theory suggests that variation in individual body size is often the result of resource availability and is controlled by trade-offs between growth, reproductive features and subsequently, survival. In the land snail Cornu aspersum , body size and correlated life history traits vary strongly intraspecifically, leading to geographic patterns of life history tactics. This work investigates the potential role of repeated exposure to stress during the growth and reproduction stage on the life history responses of two subspecies. Cornu aspersum aspersa and Cornu aspersum maxima exhibit contrasting life history strategies, as shown morphologically by the giant size of maxima . In this study, we postulated that the two subspecies would respond differently when exposed to a similar, non-specific stress. Thus, snails were regularly challenged with injections of Gram-negative heat-killed bacteria Escherichia coli suspensions. As expected, we found that stress induced by bacterial challenges leads to a significant decrease in fecundity in the two subspecies. We also observed differences between the challenged and the control snails in terms of the (1) growth features for C. a. maxima and (2) timing of the first egg-laying for C. a. aspersa . Moreover, a delayed development of the reproductive organs in the post-challenged animals suggested a trade-off between growth and sexual maturity.