Key facts
- Horizontal gene transfer (HGT) is the incorporation of a gene from one species into the genome of a distantly related species.
- A new study found thousands of bacterial DNA fragments within the genomes of multiple cockroach species.
- These bacterial DNA insertions have been present for millions of years in some cockroach lineages.
- The majority of the transferred bacterial DNA sequences do not appear to encode useful functions for the cockroaches.
- The frequency of these transfers suggests HGT may play a larger role in animal genome diversity than previously understood.
Horizontal gene transfer (HGT), the process by which genetic material is transferred between distinct species, is now understood to be more prevalent in multicellular animals than previously believed. While common among microbes due to their cellular structure, HGT in animals was thought to be rare. However, recent advancements in DNA sequencing technology, particularly long-read sequencing, have enabled researchers to identify bacterial DNA integrated into animal genomes, distinguishing it from contamination. A new study published in PNAS examined multiple cockroach species and discovered a substantial presence of bacterial DNA, with instances ranging from 93 to 4,900 per species. These fragments, often short and located outside of gene-encoding regions, suggest that HGT may contribute significantly to the diversity of animal genomes over evolutionary timescales, even if the transferred DNA lacks immediate functional utility.