A Roadmap for Using Hybridisation Capture–Based Target Enrichment of Ancient Environmental <scp>DNA</scp> in Palaeoecology

Recovering ancient DNA from environmental samples is transforming the way we understand historical ecosystems. While high-throughput sequencing of the total DNA in environmental samples (shotgun metagenomic sequencing) reveals the taxonomic contents of these samples, the genetic signals of some taxa (e.g., eukaryotes) can be weak compared to the background levels of DNA from organisms such as bacteria, requiring deep sequencing approaches that are costly. Thus, to increase cost-effectiveness, pre-sequencing enrichment of target DNA can be advantageous. One technique to enrich this target DNA is hybridisation capture, where short RNA or DNA baits are designed to match, bind and isolate specific stretches of DNA. Hybridisation capture has previously been applied to recover DNA from ancient skeletal remains, but it is only beginning to emerge as an approach to characterise organisms from ancient environmental samples. Thus, there is limited information on establishing hybridisation capture workflows for ancient environmental DNA applications, including the limitations and advantages. This mini review focuses on establishing a roadmap for the applications of hybridisation capture to ancient environmental DNA samples.