Data from: An ecological history of the relict genetic lineage of Arabidopsis thaliana

The combination of extensive population sampling with whole-genome
sequencing in the annual plant Arabidopsis thaliana has recently allowed
the identification of a genetically differentiated relict lineage. The
most important nuclei of relict A. thaliana is found in the Iberian
Peninsula and North Africa, although relict accessions have also been
found scattered across Atlantic oceanic islands, eastern Mediterranean
Basin, South and East Africa and China. We hypothesised that relict A.
thaliana long survived and adapted to a wide array of environments in the
Iberian Peninsula and North Africa due to the fact that the region
repeatedly acted as glacial refugia. Given the lack of evidence to support
this hypothesis, we addressed this issue by studying the ecological
history of Iberian and North African relict A. thaliana. To this end, we
analysed the relationship between the current habitat suitability of
relict A. thaliana, estimated with species distribution models, and the
vegetation dynamics in the region over the last millennia using pollen
fossil data from sediment cores and reconstructions of past distribution
ranges of the most important tree species occurring in the region.
Overall, our results indicated that a higher current habitat suitability
of relict A. thaliana was correlated with more stable vegetation dynamics
since the Last Glacial Maximum and during the Holocene. Given that relict
A. thaliana is known to harbour genetic variation specific to its relict
nature, we also evaluated the differentiation between relict and
non-relict A. thaliana accessions at the functional genetic level for the
known flowering genes, CRY2 and TSF. Genomic surveys detected the
existence of haplogroups of these genes occurring at very high frequency
only among relict accessions. Overall, our study reinforced the relict
character of this lineage thought to be at the base of the species'
early history. We stress the need to sample in depth other geographic
areas harbouring relict A. thaliana and conduct further functional genetic
analyses between relict and non-relict accessions to keep disentangling
the evolutionary trajectory of this annual plant.