Recurrent horizontal gene transfers across diverse termite genomes.

Area of Science:

• Genomics
• Evolutionary Biology
• Molecular Biology

Background:

• Horizontal gene transfer (HGT) is a key driver of innovation in prokaryotes.
• The role and extent of HGT in eukaryotes, particularly insects, remain largely unexplored.
• Termites and cockroaches (Blattodea) offer a unique model to study HGT due to their complex symbiotic relationships.

Purpose of the Study:

• To investigate the occurrence and impact of HGT from non-metazoan organisms in termite and cockroach genomes.
• To identify the sources and characteristics of horizontally acquired genes in these insects.
• To understand the evolutionary fate and functional significance of HGTs in Blattodea.

Main Methods:

• Comparative genomics analysis of 45 termite and 2 cockroach high-quality genomes.
• Identification and classification of horizontally transferred genes and pseudogenes.
• Phylogenetic analysis to determine HGT origins and evolutionary trajectories.

Main Results:

• 281 estimated HGT events identified, contributing 289 genes and 2,494 pseudogenes across 168 orthologous groups.
• Wolbachia identified as the predominant HGT source; termite gut bacteria and Blattabacterium showed minimal contribution.
• Horizontally acquired genes were often recent, species-specific, prone to duplication and pseudogenization, and evolved faster than native genes.
• Mobile genetic elements and genetic information processing genes were frequently transferred.

Conclusions:

• Termites exhibit continuous gene acquisition via HGT, with most events being lineage-specific.
• Acquired genes in termites and cockroaches appear largely non-functional and tend to be lost over time.
• HGT plays a dynamic, albeit often transient, role in the evolution of insect genomes.