Fast-Renewed Inbreeding Depression in Animals – FRIDA

Mutations are the fuel of evolution, but most of them are deleterious. Thus, our genomes permanently carry a mutation load, which is the basis of a very general phenomenon in diploids : inbreeding depression (ID). ID is the loss of fitness in inbred individuals, and we think we know its origin well : it results from the homozygosity of recessive deleterious mutations. Yet, ID is sensistive to parental condition, and especially to treatments that affect epigenomes, suggesting an epigenetic component. Some preliminary results we produced support this idea : they show that ID can persist even when we make sure that offspring of consanguineous and nonconsanguineous matings are genetically identical. This suggests a process able to generate variation and ID in a few generations, too fast a pace for classical mutations. Our project will explore this fast-renewed ID using a combination of experiments. We will replicate and develop the preliminary experiment in more genotypes and more species, and compare the results to predictions of models incorporating both classical mutations and epimutations. We will test whether parental environments affect ID in offspring (a typical feature of epigenetic transmission), and we will explore the impacts of inbreeding on epigenomes. We will do the experiments on two invertebrate animal models, hermaphroditic and allogamous, easy to breed and capable of self-fertilization. Our consortium gathers specialists from 4 institutes with complementary skills (modelling, bioinformatics, matig system evolution, epigenomics). This project has the potential to change the current paradigm of ID, a central process both in basic evolutionary biology and for the conservation of captive and wild populations ; we therefore expect it to have a high impact.