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This study examined Argentine ant populations across mainland and island locations in Spain and Greece to understand how isolation affects the genetic and behavioral unity of the invasive European supercolony. Researchers found that while most colonies belonged to the established main supercolony, one Greek colony represented a previously unregistered supercolony that showed genetic, chemical, and behavioral differences. Chemical analysis revealed unexpected patterns suggesting Argentine ants may have colonized Greece via Crete rather than the mainland, and that local adaptations are beginning to fragment what was thought to be a genetically homogeneous supercolony.
Why it matters
The findings suggest that the invasive success of Argentine ants may be less stable than previously thought, as local evolution is creating competitive divisions within the supercolony. This has implications for predicting and managing invasive species spread, and demonstrates how introduced populations can rapidly diverge even while maintaining connectivity across thousands of kilometers.
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⚠️ Preprint – Noch nicht peer-reviewed
Dieser Artikel wurde noch nicht von unabhängigen Experten begutachtet. Die Ergebnisse sind vorläufig und sollten mit Vorsicht interpretiert werden.
The introduction of alien species into new habitats stands as a pressing economic and ecological challenge but it is also essential for unveiling evolutionary processes. The introduction of the Argentine ant (Linepithema humile) led to the spread of a single supercolony through different continents and thousands of kilometres like in Europe, from Northwest Spain to Greece. It was assumed that the high invasiveness of the species mainly relied on the lack of agonism among colonies, an effect derived from its introduction. However, recent studies suggest that local adaptations and evolutionary divergence could involve the disruption of the Argentine ant empire into a mosaic of competitive colonies. We investigated how isolation affects population divergence by comparing mainland and island populations in two distant regions colonized in Spain and in Greece with morphology, agonism, cuticular hydrocarbons, and genetic diversity of ant workers. Our results showed that all colonies sampled belonged to the most spread supercolony in Europe (main supercolony) except one sampled in Crete (Heraklion; Greece), which resulted to be a supercolony not registered in Europe. The Heraklian supercolony showed a different chemical and genetic profile and hostile agonism towards the other Greek colonies. Differences between islands and mainland colonies belonging to the main supercolony were higher in Galiza than in Greece. Surprisingly, the chemical profile of the Cretan colony belonging to the main supercolony showed more similarity with the Galizan colonies than with the Greek mainland, suggesting that L. humile may have been introduced into Greece through this island instead of the mainland. Our study suggests that local adaptations in Argentine ant colonies can trigger competition between colonies. Our data strongly support the existence of a candidate supercolony which highlights either ongoing introductions of L. humile in Europe or gaps in our understanding of its metapopulation dynamics.
Source: Isolation and introductions disrupt the homogeneity of Argentine ants in Europe.