SedaDNA metabarcoding reveals hidden histories of within-species sequence variation

A recent study published in <source>ca8e27f9-6eb</source> has shed light on the untapped potential of sedimentary ancient DNA (sedaDNA) for uncovering historical changes in within-species genetic variation. Traditionally, genetic data have been derived from contemporary populations, leaving gaps in understanding how species' genetic compositions have evolved over time.

To explore this, researchers analyzed sediment cores from eight coastal wetlands across Atlantic and Mediterranean regions. These cores were dated and subjected to COI and 18S metabarcoding, a technique that treats amplicon sequence variants as potential haplotypes. The study aimed to assess how accumulated haplotype diversity and geographic sharing varied among different species and markers.

The results were intriguing. The analysis revealed that haplotype diversity and geographic sharing were not consistent indicators of species status. Instead, temporal reconstructions showed that these factors combined distinct sets of genetic variants observed across different historical periods. Moreover, when examining the 18S data, researchers found substantial variation in haplotype composition among different periods, locations, and species.

By mapping the temporal and spatial distributions of within-species genetic variants, the study demonstrates the value of sedimentary DNA archives in uncovering historical dimensions of biodiversity that are often obscured by aggregating genetic data from contemporary populations. This approach establishes a foundation for a new field called historical metaphylogeography, which seeks to reconstruct the evolutionary history of species' genetic diversity over time and space.