ddRAD sequence data of 19 grassland plant species: evolution during cultivation

A growing number of restoration projects require large amounts of seeds. As harvest in natural populations cannot cover the demand, wild plants are propagated in monoculture at agricultural fields as crops. There are concerns that the cultivation process may cause genetic drift and selection, which would alter genetic properties of the cultivated populations and reduce their genetic diversity. Such changes could reduce the pre-existing adaptation of the restored populations, and limit population adaptability to environmental change.We used ddRAD sequencing (enzymes EcoRI and MspI) to identify single nucleotide polymorphism (SNP) markers. Using a pool sequencing approach we test for genetic differentiation and changes in gene diversity between the source populations and up to four consecutive generations in cultivation grown from this source for 19 wild plants species (Achillea millefolium, Anthoxanthum odoratum, Centaurea jacea, Centaurea scabiosa, Crepis biennis, Cynosurus cristatus, Dianthus carthusianorum, Galium verum, Leontodon hispidus, Leucanthemum ircutianum, Lotus corniculatus, Lychnis flos-cuculi, Ranunculus acris, Rumex acetosa , Salvia pratensis, Silene dioica, Silene vulgaris, Trifolium pratense, Veronica teucrium). We then linked the magnitude of the genetic change to species-specific breeding system and seed dormancy to understand if the genetic change depends on these traits.Propagation of native seeds for ecosystem restoration only moderately changed genetic composition of the cultivated generations. Importantly, the genetic differentiation as a consequence of cultivation was much lower compared to genetic differentiation between populations coming from distinct regions. The propagated generations harbored even higher gene diversity than wild collected seeds. The genetic change was stronger in self-compatible species, probably as a result of increased outcrossing rate in the monoculture.In conclusion, large-scale seed production maintained the genetic integrity of the natural populations. Increased genetic diversity may even imply increased adaptive potential of the propagated seeds, which makes them especially suitable for ecological restoration. However, we have been working with seeds from Germany and Austria, where the seed production is regulated and certified. Whether other seed production systems perform equally well remains to be tested.