Slow life history and rapid extreme flood: demographic mechanisms and their consequences on population viability in a threatened amphibian
Abstract
1. In the Northern Hemisphere, an increase in both the frequency and magnitude of violent flooding events has been reported due to climate change. According to life history theory, one might postulate that in ‘slow’ species: (i) environmental canalisation may act as a selective force that minimises to some extent adult survival variations caused by catastrophic flood and (ii) extreme flooding events would cause important variations in recruitment and young survival. Hence, it may be hypothesised that (iii) the population growth rate of ‘slow’ species might be relatively insensitive to changes in the frequency of extreme climatic events if adult survival remains largely unaffected.
2. In this study, we investigated how extreme rainfall events resulting in severe flood impact popula- tion dynamics of a long-lived endangered amphibian, the yellow-bellied toad (Bombina variegata: Bombinatoridae). To address this issue, we used capture–recapture (CR) data collected on two populations (768 and 1154 individuals identified) in southern France and developed multi-event CR models.
3. Our results indicated that extreme flooding did not cause any variation in sub-adult or adult survival, whereas recruitment and juvenile survival were negatively impacted. Furthermore, our simulations indicated that the population growth rate was only marginally sensitive to potential changes in the frequency of extreme flooding in the future.
4. Hence, we suggest that extreme flooding does not appear to be a proximal factor of extinction risk for this endangered amphibian species.