ANR PRC ORIGAMIS funded

Joris Bertrand (coordinator), Anaïs Gibert and I received an ANR PRC (collaborative research) to study speciation in Ophrys orchids. You can look at Joris and Anaïs research here. This project will tackle the challenge of population genomics of speciation in species with large genomes. We will focus on both SNPs and TEs. The funding should cover two post-doctoral researchers, stay tuned!

The summary is reproduced below:

Orchids in the genus Ophrys have a fascinating pollination strategy (sexual swindling). Their flowers mimic the visual, olfactory and tactile characteristics of female pollinator insects to such an extent that the males of these species are attracted, attempt to mate with the flower, and take pollen with them, which they will transfer to the flower of another plant without knowing it, by being lured once again. The Ophrys flower form therefore a set of ‘magic traits’ that play a key role in the speciation process. The high degree of specialisation in this plant-insect interaction is also thought to be a driving force underlying the rate of diversification observed in Ophrys. But these plants have other characteristics that could favour their diversification. Firstly, the still incomplete reproductive barriers between most species in the genus allow a certain amount of gene flow between lineages. It is increasingly well documented that these genetic exchanges can be responsible for the acquisition of adaptive variation in groups undergoing evolutionary radiation. Secondly, Ophrys have a large genome (> 5 Gbp) with a complex composition (more than 70% transposable elements) that could provide raw material for generating variation, a source of biological innovation, but the study of which represents a technical challenge. Ophrys therefore present a rare and perhaps unique opportunity to study the early stages of speciation right up to the most remarkable evolutionary radiations, by providing a biological system that combines three ingredients that are particularly favourable to the diversification of lineages. In ORIGAMIS, we propose to implement a highly integrative approach based on multi-omic data (genomics, transcriptomics, metabolomics, phenomics and fitness proxies) to study the genomic architecture of magic traits and their impact on population divergence, as well as the contribution of adaptive introgression in Ophrys aveyronensis, a species with a disjunct geographic distribution for which we have been able to highlight islands of genomic divergence at different spatial and taxonomic scales. This system can therefore be used to study the consequences of parallel adaptation to different ecological conditions in a ‘simplified’ geographical context, following a relatively recent vicariance. We would like to test whether these islands of divergence could correspond to structural variants (in particular chromosomal inversions) and, if so, whether these regions where recombination is reduced could host loci functioning as supergenes and whose expression produces pleiotropic effects on several traits of the floral phenotype (morphology, colouration, odour) and indirectly on the ability of individuals to survive and reproduce. Innovative phenotyping of plants using 3D scanners will make it possible to quantify the flower in an exhaustive way, producing long-term data, free from experimenter bias. Analyses using Artificial Intelligence will be employed to identify the most relevant variables and analyse them. Finally, we will study whether these islands of divergence formed de novo or could have been acquired by introgressive hybridisation from sympatric congenic species. This project could thus contribute to the emergence of a promising new biological model for linking the processes at work at micro-evolutionary scales and studying their consequences at the scale of adaptive radiations, based for the first time on whole-genome resequencing and phenomics, on a taxon that lends itself well to scientific popularisation and participatory science initiatives.