Understanding biological extinction is a central topic in evolutionary biology and paleontology. After the mass extinction of non-avian dinosaurs, the Eocene-Oligocene transition (ca. 33.9–33.5 Ma) is considered as a key step in Cenozoic climate evolution and it coincides with one of the main extinction events in Europe during the Cenozoic: the Grande Coupure (GC). Most of the species documented in Europe after the GC had no close relatives in the preceding fauna. Indeed, mammals had evolved independently in island Europe during the Eocene, after the North Atlantic split from North America ca. 53 Mya. The overarching goal of DEADENDER is to dissect the process of biological extinction using Endemic European Artiodactyls (EEA) to investigate the response of related animals to local environment changes, and the impact of biotic drivers on their specific diversity (and final decline). DEADENDER proposes an innovative approach combining the most accurate fossil record at world scale for the Eocene-Oligocene interval with cutting-edge analytic methods, both in terms of 3D morphological investigation and of diversity dynamics. This project will exploit the unparalleled fossil record from the Quercy phosphate infillings localities in France (certified UNESCO Global Geopark) to test the impact of biotic (intrinsic like diet, body mass, brain complexity, or extrinsic such as competition with other mammals or predation) and abiotic factors (temperature, sea level) on the diversity dynamics of EEA. DEADENDER contrasts with previous approaches by its integrative, multifactorial nature, combining altogether biotic and abiotic factors to get a better understanding of the response of organisms to environmental changes. This comprehensive approach will allow an accurate understanding of the drivers of diversity dynamics for a given clade.
DEADENDER is composed of two complementary work packages. The first one aims at getting an accurate picture of the EEA in terms of specific diversity, temporal distribution, and ecology – before, at, and after the GC. This will set 1) an up-to-date systematic framework for fossil artiodactyls from Quercy, 2) a refined temporal setting for Quercy fossiliferous localities, and 3) an accurate, multi-proxy determination of the paleoecology of extinct Quercy artiodactyls (3D dental microwear analyses + virtual reconstruction of brain cast and inner ear based on CT data). The second work package will explore the tempo of speciation and extinction of EEA clades and the contribution of abiotic (past environmental changes) and biotic factors (clade competition, species traits) over their diversity dynamics. It will also provide precious information on the evolutionary mechanisms that underlie phenotypic evolution of EEA clades, which may determine their response to environmental and biotic stresses.
Accordingly, DEADENDER will allow for: 1) clarifying basal relationships of EEA clades within Artiodactyla phylogeny, 2) providing accurate speciation and extinction rates through time for each EEA clade, 3) defining the effect(s) of environmental variables on speciation and extinction of each EEA clade and of EEA groups sharing similar ecological/physiological characteristics, 4) identifying the role of competition on the speciation and extinction rates of each EEA clade, and 5) exploring the mechanisms that underlie phenotypic evolution of EEA clades. Altogether, this will give access to key aspects of the EEA extinction including the understanding of specificities of extinction victims, survivors, and replacement taxa, and potential links between life history traits and extinction magnitude/survivorship per clade.
The deliverables of DEADENDER will directly document the diversity and evolutionary potential of species to adapt to past environmental changes. In the general context of worldwide erosion of biodiversity, beyond scientific community, DEADENDER has several potential outreaches for a general audience.
Madame Maeva Orliac (Institut des Sciences de l'Evolution de Montpellier)
The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.
ISEM Institut des Sciences de l'Evolution de Montpellier
Help of the ANR 178,308 euros
Beginning and duration of the scientific project: October 2018 - 42 Months