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Altered eco-evolutionary feedbacks in a future climate

Periodic Reporting for period 1 - ECOFEED (Altered eco-evolutionary feedbacks in a future climate)

Reporting period: 2019-04-01 to 2020-09-30

Predicting the consequences of climate change on biodiversity and ecosystem functioning is a pressing challenge since it constitutes a major threat to biodiversity. Current scenarios predict an accelerated erosion of biodiversity with climate change. However, uncertainties in these predictions remain large because the multiplicity of climate-change effects at all biological levels, from genes to ecosystems, and their interdependencies are still overlooked. Climate change can modify species phenotype and performance through phenotypic plasticity and evolution. The microevolution of keystone species can spread throughout the whole ecological network due to changes in species interactions. Conversely, direct impacts of climate on communities and ecosystems can have ripple effects on the phenotypic distribution and evolution of all species of ecological networks.

Climate-driven changes at individual and population levels can therefore shape community composition and ecosystem functioning, and vice versa, altering eco-evolutionary feedbacks, namely the reciprocal interactions between ecological and evolutionary processes. Climate-driven ecological and evolutionary dynamics are yet often investigated separately. The role of eco-evolutionary feedbacks in climate change impacts on biological systems therefore hinges on little concrete empirical evidence contrasting with a profuse theoretical development.

ECOFEED investigates climate-dependent eco-evolutionary feedbacks using a realistic warming experiment reproducing natural conditions and thus allowing for both evolutionary and ecological dynamics to occur under a predicted climate change scenario. We will quantify the impacts of warmer climates on the evolution of top predator’s phenotype (Common lizards, Zootoca vivipara, WP1) and on communities structure and ecosystem functioning (WP2), and then experimentally Additional experimental studies will test for the reciprocal effects of evolutionary and ecological dynamics (WP3-4) and isolate the direct impacts of climate-induced changes of top predator phenotype on community and ecosystem functioning, and in turn the direct effects of climate-induced changes of community and ecosystem on this top predator. The reciprocity of effects between ecological and evolutionary dynamics will outline the extent of eco-evolutionary feedbacks (WP5).
The project is taking advantage of a long-term warming experiment started in 2015 completed with the databases from short-term warming experiment ran between 2012 and 2014. For these first 18 months, we kept the 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, birth and phenotypic traits of adults 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 trophic interactions (e.g. diet).

Simultaneously, we kept monitoring the changes in the ecological networks of mesocosms with present-day and warm climates (WP2). We are monitoring plant and invertebrates communities as well as the microbial communities in lizards’ gut, invertebrates and in the soil to build ecological networks and estimates climate-dependent changes in their structure and in tropic interactions.

Most samples from the long-term experiment are being analyzed (i.e. stable isotopes for the diet, metabarcoding for the microbial communities) and were postponed due to the COVID-19 crisis. However, we used the databases from our short-term experiments using the exact same methods to explore and predict evolutionary and ecological dynamics.

From the repeated short-term experiments, we found that both thermal traits and trophic traits were influenced by climatic treatments. Common lizards, our top predator, had a paler color and preferred lower thermal temperatures in warmer habitats 8 months after our climate manipulation (Bestion et al. in preparation) and those changes mostly resulted from plastic changes to prevent overheating. Simultaneously, lizards changed their diet (Bestion et al. 2019, https://doi.org/10.1098/rspb.2019.2227). They were more specialized and eat more predatory invertebrates (e.g. spiders) than herbivores ones (e.g. orthoptera). These changes, belonging to the WP1, were related to changes in gut microbial communities, with a loss of diversity, and may have knock-on effects on invertebrates’ communities (WP2). We expect further changes arising from the long-term manipulation of climatic conditions.
Despite a hampering COVID-19 situation, we have already made substantial progress beyond the state of the art:

i. We have set-up a long-term warming experiment monitoring both the evolutionary and the ecological dynamics in nearly natural conditions to estimate feedbacks between these dynamics.
ii. We revealed from our databases that the top predator may experience large phenotypic modifications of thermal physiology and diet (Bestion et al. in preparation, Bestion et al. 2019).
iii. These phenotypic changes may have large consequences on species interacting with lizards including microbial and invertebrate communities (Bestion et al. 2019).

These results allow us to expect stronger modifications of ecological and evolutionary dynamics by the end of the project.