Ancestral complexity and constrained diversification of the ant olfactory system

Area of Science:

• Zoology
• Neuroscience
• Chemical Ecology

Background:

• Social insects like ants rely on chemical communication for colony cohesion and cooperation.
• A specialized olfactory subsystem, processing cuticular hydrocarbons (CHCs) for nestmate recognition, is crucial for ant sociality.
• The evolutionary origins and phylogenetic distribution of this ant olfactory system are largely unknown.

Purpose of the Study:

• To investigate the evolutionary origins and phylogenetic distribution of the ant olfactory system.
• To explore the relationship between olfactory system sophistication, CHC profile complexity, and social traits in ants.
• To understand the co-evolutionary dynamics between CHC profiles and olfactory neuroanatomy.

Main Methods:

• Comparative neuroanatomical analysis of the olfactory system across eight major ant subfamilies.
• Gas chromatography-mass spectrometry (GC-MS) to analyze cuticular hydrocarbon profiles.
• Behavioral assays to assess nestmate recognition capabilities.

Main Results:

• The ant olfactory system exhibits deep evolutionary roots, with sophistication not directly linked to social traits like colony size or foraging strategies.
• Antennal lobe investment in the olfactory system correlates positively with the complexity of cuticular hydrocarbon profiles.
• Despite neuroanatomical variations, diverse ant species demonstrate consistent nestmate discrimination abilities, adapting to chemical diversity.

Conclusions:

• The evolution of the ant olfactory system is deeply rooted and shaped by chemical diversity rather than social complexity.
• Cuticular hydrocarbon profile complexity and neuronal investment in olfactory neuropils have co-evolved to maintain reliable social recognition in ants.
• This co-evolutionary process underscores the adaptive significance of chemical communication in sustaining ant sociality.