Isolation and Local Adaptation Disrupt Argentine Ant Supercolony Homogeneity in Europe
A new preprint study reveals that the Argentine ant's vast European supercolony — spanning from Spain to Greece — is showing signs of genetic, chemical, and behavioral divergence, particularly in island populations. Researchers compared mainland and island colonies using morphology, genetics, cuticular hydrocarbons, and aggression tests, discovering a previously unregistered supercolony in Crete. The findings challenge the assumption that the species' invasiveness depends on uniform, non-aggressive colony behavior, suggesting local adaptation may be breaking down the ant 'empire.'
The Argentine ant (Linepithema humile) is one of the world's most successful invasive species, having spread a single dominant supercolony across Europe from northwest Spain to Greece. A new preprint on bioRxiv investigated whether geographic isolation — particularly on islands — drives population divergence within this supercolony. Researchers sampled colonies in Spain's Galiza region and in Greece, analyzing genetics, body morphology, cuticular hydrocarbons (chemical recognition signals), and agonistic (aggressive) behavior between colonies. Nearly all sampled colonies belonged to the known main European supercolony, but one colony from Heraklion, Crete was identified as a distinct, previously unregistered supercolony in Europe, displaying a different chemical and genetic profile and showing hostility toward other Greek colonies. Intriguingly, the chemical profile of the Cretan colony that did belong to the main supercolony more closely resembled colonies from Galiza than from the Greek mainland, hinting that the ant may have reached Greece via Crete rather than overland. Divergence between island and mainland populations was more pronounced in Galiza than in Greece. The authors conclude that local adaptation can trigger inter-colony competition and that the discovery of the Heraklian supercolony points either to ongoing new introductions of the species into Europe or to significant gaps in understanding its metapopulation dynamics.
What's missing
As a preprint, this study has not yet undergone peer review, so findings should be treated as preliminary. The study does not detail sample sizes per location or address whether the Heraklian supercolony's origin could be traced to a specific source population outside Europe.
What different sources said
- bioRxivCenter
Isolation and introductions disrupt the homogeneity of Argentine ants in Europe.
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