Opening new avenues to model the DYnamics of Species aSsemblages by integrating Ecology and Evolution: a case study from the mountain ecosystems of the Alps and the Carpathians – ODYSSEE

The originality of the project is to examine multiple components of biodiversity (including taxonomic, functional and phylogenetic diversity) and to characterize these components for plants, soil fauna and soil microbial communities. This requires the development of innovative analytical methods such as the study of soil DNA using metabarcoding approaches, but also new biostatistical methods for the combined analysis of all these components of biodiversity.

The ODYSSEE project allows to assemble a comprehensive reference database on the components of biodiversity in mountain grasslands of the Alps and the Carpathians. Our work shed light on the overlooked diversity of soil mesofauna (especially springtails). The study of the spatial distribution of biodiversity at the biogeographic scale can now be conducted on previously neglected groups of organisms.
We have developed diagnostic tools to study soil environmental DNA and infer the molecular diversity of soil organisms. We jointly analyze the phylogenetic, environmental and spatail factors that determine the assembly of species in ecosystems. This research is pivotal because it will lead to improve scenarios of biodiversity in response to global changes.

The history of the mountain grasslands of the Alps and the Carpathians will be reconstructed through the combined analysis of the genetic diversity of plants, animal and fungal communities in soil. A main focus will be to understand how species assemblages have recolonized these mountains the last glacial maximum.
The analysis of soil environmental DNA opens up fundamental research perspectives (comparative analysis of the distribution of a large molecular taxa pool) and applied research perspectives (contribution to the development of biological indicators for the soil ).
Finally, data from the project will allow to calibrate and validate an integrated model simulating species assemblages belonging to different trophic levels accounting for historical, spatial and ecological constraints.

A paper submitted to The New Phytologist is currently under revision (Gérémia & al. Contrasting microbial biogeographical patterns between anthropogenic subalpine grasslands and natural alpine grasslands).

A thematic school on DNA metabarcoding was held in Romania in May 2015

The impact of global change on ecosystems prompts researchers to develop new conceptual and modeling frameworks to understand and predict the dynamics of biodiversity across levels of complexity, i.e. from population to species assemblages and from ecosystems to landscapes. This challenge requires cross-fertilization of dispersed disciplines such as ecology, evolutionary biology and the science of the earth system. Predictive models of biodiversity should no longer ignore the legacy of evolutionary history and biotic interactions. We need to know how species have responded to past changes in habitat distribution to understand current patterns of diversity and to evaluate how organisms will track future changes.

ODYSSEE aims at integrating ecology and evolution to understand and predict the dynamics of species assemblages at a biogeographical scale. The project will focus on the high mountain ecosystems of the Alps and the Carpathians that represent a hotspot of plant diversity in temperate Europe and that are particularly exposed to severe habitat loss due to global change and land use changes. These nowadays highly fragmented landscapes have undergone severe periods of contraction and expansion over the last two millions years. Moreover, the impacts of Quaternary climatic variations on the spatial distribution of cold habitats have been very different between the Alps - which were largely ice covered - and the Carpathians - which were impacted far less by glacier advances than the Alps. This contrasting history has had profound consequences on the location of thermal refugees, post-glacial recolonization routes, and community re-assembly following climate warming. However, these historical footprints have been documented for a few species, and never for multi-trophic species assemblages (such as plants-soil microflora-soil mesofauna networks). This hinders our capacity to forecast the response of integrated levels of biodiversity to global change.

ODYSSEE will build on existing knowledge to assemble an unprecedented dataset on the biodiversity of two types of widely distributed mountain grasslands across the Alps and the Carpathians: the extensively managed alpine meadows dominated by Carex curvula and the more intensively managed subalpine grasslands dominated by Nardus stricta. Different components of biodiversity will be studied including phenotypic and genetic diversity of keystone plant species, taxonomic and functional diversity of plant species assemblages and molecular diversity of soil microflora and mesofauna. This will provide unique opportunities to examine spatial co-variations across levels of biodiversity and across multi-trophic species assemblages.

ODYSSEE will integrate our best knowledge of how community assembly is driven by ecological processes (environmental filtering, biotic interactions, mass effect) and past evolutionary history. The ultimate challenge will be to develop and test meta-community models able to track the response of species assemblages to environmental changes in a dynamic landscape. The empirical data gathered in the two targeted mountain ecosystems will be used as a benchmark to evaluate the performance of this new integrated framework.

ODYSSEE will make use of key innovative approaches in the science of diversity including (i) the reconstruction of megaphylogenies, (ii) the assessment of soil molecular diversity using DNA metabarcoding (iii) the development of spatial multivariate analyses, (iv) the improvement of community-based modeling of biodiversity.

Beyond these fundamental objectives, ODYSSEE will aim at sharing scientific knowledge and methodological expertise among French and Romanian partners and will include an ambitious training program for graduate students, researchers and technical staff of both countries.