Convergent eusocial evolution is based on a shared reproductive groundplan plus lineage-specific plastic genes

Area of Science:

• Evolutionary biology
• Genomics
• Insect behavior

Background:

• Eusociality, a complex social structure with reproductive division of labor, has evolved independently multiple times in insects.
• The genetic underpinnings of these independent evolutionary events and the extent of shared genetic mechanisms remain largely unexplored.

Purpose of the Study:

• To investigate the genomic basis of caste differentiation in two independently evolved eusocial insects: the pharaoh ant (Monomorium pharaonis) and the honey bee (Apis mellifera).
• To identify shared and lineage-specific genes associated with caste-based division of labor across different developmental stages and body segments.

Main Methods:

• Comparative transcriptomic analysis of caste-specific gene expression profiles in pharaoh ants and honey bees.
• Examination of gene expression across developmental stages and adult body segments (e.g., abdomen).
• Identification of conserved gene sets and lineage-specific gene recruitment in eusocial evolution.

Main Results:

• A conserved core of genes, upregulated in the abdomens of queens in both species and also in mated female flies, suggests a shared insect reproductive groundplan.
• Few genes showed common differential expression outside of this conserved groundplan.
• The majority of caste-associated genes are plastic, rapidly evolving, and evolutionarily young, indicating significant lineage-specific genetic innovation.

Conclusions:

• The convergent evolution of eusociality relies on a combination of highly conserved genes and novel, lineage-specific gene recruitment.
• Independent origins of sociality utilize distinct genetic pathways, shaped by both conserved genetic resources and rapid evolutionary adaptation.