Crop wild relatives (CWR) play a key role in providing genetic diversity for crop adaptation and improvement and their in situ conservation is the most appropriate action to safeguard them, as it allows new diversity to be generated. Knowledge about contemporary evolutionary processes, adaptive responses to climate change, and trends in genetic diversity status should support the identification of target populations for in situ management and monitoring actions. Generating this knowledge requires monitoring and assessing diversity at various time points. Analyses of past trends have been particularly limited for CWR due to patchy, scarce availability of historical data and seed material, which would constitute a historical baseline for comparison with contemporary populations. Past germplasm collecting missions and their associated documentation can contribute to filling this gap. We analysed as a potential resource the Bioversity Collecting Database, which includes sample-level records for over 200,000 landrace and CWR samples mainly collected between 1975 and 1995. 27% of the samples collected are wild species, of which 73% are georeferenced. The database links original sample passport data with collecting reports and with accession numbers from the genebanks conserving the collected material, which allows the seeds collected to be tracked. This data resource was used to implement a study on temporal variation in wild barley. Wild barley (Hordeum vulgare subsp. spontaneum), originally collected in 1981 and stored in genebanks, was re-collected from historical sites in Jordan. Most original accessions from the 1981 mission were traced in genebanks and phenotypic and molecular marker data compared between the 1981 and 2012 collections.
