The project is taking advantage of a long-term warming experiment started in 2015 completed with the databases from short-term warming experiments ran between 2012 and 2014. From 2015 to 2022, we ran a long-term warming experiment, quantifying the population dynamics and the phenotypic changes of common lizards, our top predator, and the evolutionary processes involved in these changes (i.e. selection and plasticity, WP1). To do so, we monitored the survival, growth rate, reproduction and phenotypic traits of adult lizards and newborns inhabiting the mesocosms undergoing present-day and warm climates. The phenotypic traits chosen belong to the management of thermal conditions (e.g. melanism and thermal preferences) and to their interactions with other species (e.g. diet, microbiome). We examined the climate-induced temporal changes, heritability and strengths of selective and plastic responses of these traits. Our results support our “live fast, die young” scenario with a faster growth rate in juveniles, an earlier reproductive onset and a faster ageing. This faster pace-of-life led to population structure towards younger and bigger individuals matching predictions made in natural populations and was coupled with a paler color and a lower thermal preference, plasric changes preventing overheating. Lizards also increased their activity in early life, likely to sustain the increased energetic needs of a faster growth, and had a more specialized diet towards predator invertebrates. These changes were further related to changes in gut microbial communities, with a loss of diversity in warmer climates increasing over time and may have knock-on effects on invertebrates’ communities (WP2).
We indeed quantified climate-induced changes across the ecological network including or not the top predator. Our results revealed that the presence of top predators reversed the effect of warming on ecological networks. In their presence, we observed a decrease of invertebrate predators – on which they preferentially feed on – together with an increase of invertebrates herbivores and a decrease of plants and soil microbes diversity. An opposite trend was found when lizards were absent.
The last project’s objective was to study reciprocal effects on the top predator and on the ecological networks. On one hand in warmer climates lizards consumed more invertebrate predators than herbivores leading to their lower proportions in the invertebrate communities and to a reduced pressure on invertebrate herbivores cascading down to plants and related soil communities. This suggests top-down cascading effects through a diet shift in top predators caused by warming. On the other hand, climate-induced changes in invertebrate communities, a lower abundance of predator invertebrate, strengthened diet shit in the top predators which should reinforced the changes of ecological networks and may endanger invertebrate community. Overall, the project demonstrates that the evolutionary and ecological impacts of climate change, acting directly or indirectly through trophic cascades at multiple biological levels. These evidences underscore the critical need to better account for incorporate eco-evo dynamics into our climate change impact predictions.
