Five thousand years of tropical lake sediment DNA records from Benin
Résumé
Until now, sedimentary DNA (sedDNA) studies have only focused on cold and temperate regions were
DNA is relatively well preserved. Consequently, the tropics, where vegetation is hyperdiverse and natural
archives are rare, have been neglected and deserve attention. In this study, we used next-generation
sequencing to barcode sedDNA from Lake Sele, localized in the tropical lowlands of Benin (Africa), and
compared the taxonomic diversity detected by DNA analyses with pollen assemblages. Plant sedDNA was
successfully amplified from 33 of the 34 successfully extracted samples. In total, 43 taxa were identified
along the 5000 years spanned by the sediment: 22 taxa were identified at the family level and 21 at the
genus level. The plant diversity recovered through sedDNA from Lake Sele showed a specific local signal
and limited overlapping with pollen. Introduced plants, grown and cultivated close to the water, such as
sweet potato, were also well recorded by sedDNA. It appears, therefore, to be a promising approach to
studying past diversity in tropical regions, and could help in tracking the introduction and history of
agriculture. This is the first time this method has been used in the field of domestication and dissemination
of several specific crops, and the results are very encouraging.