The Gala´pagos Islands constitute one of the most pristine tropical systems on Earth. However, the complex and fragile equilibrium of native species is threatened by invasive species, among which is one of the most successful ants in the world, the tropical fire ant, Solenopsis geminata. We characterized the genetic structure and diversity of populations of S. geminata in the Galapagos Islands and unravelled the archipelago colonization by combining Bayesian clustering methods and coalescent-based scenario testing. Using 12 microsatellite markers and one mitochondrial DNA fragment (COI), we analysed individuals collected in all main invaded islands of the archipelago and from the native areas in Costa Rica and mainland Ecuador. We also used mitochondrial DNA to infer evolutionary relationships of samples collected in Galapagos Islands, Ecuador, Costa Rica and other Latin American countries. Our results showed that genetic diversity was significantly lower in Galapagos Islands and mainland Ecuador populations when compared to Costa Rican populations, and that samples from Galapagos Islands and mainland Ecuador (Guayaquil) clustered in a single group and all share a single mtDNA haplotype. Approximate Bayesian Computation favoured a scenario assuming that populations from Galapagos Islands diverged from mainland Ecuador. The city of Guyaquil, an obligatory hub for tourism and trade, could act as a bridgehead.
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Objective: This study aimed at examining ant communities of port and border cities in order to identify introduced and potential invasive ant species and microhabitats likely to contribute to the spread of these ant species. Therefore, the sampling design are linear transects of 200 metres on which ants were collected using tuna baits at 15, 30, 45 and 60 minutes in the two port cities of Abidjan and San Pedro, and seven cities that are Man, Touba, Odienne, Ferkéssedougou, Bouna, Bondoukou and Abengourou located near the borders of Côte d’Ivoire. The results showed 83 ant species including 9 potential introduced or invasive ant species. These invasive ants contributed importantly to the ant assemblage in port cities (23.95±2.7 % of total richness and 37±6.1 % of total abundance) and border cities (20.17±4.7 % / 30.6±7 %). In addition two notorious invaders, Solenopsis geminata (Fabricius, 1804) (Tropical fire ant) and Pheidole megacephala (Fabricius, 1793) (Big-headed ant) were detected during this study. The results also indicated that potential introduced or invasive ant species were mostly detected in microhabitats where human activities are uninterrupted such port zones, markets, domestic streets and residential. Conclusion: In the end, this study has shown that ant communities in port and border cities harbour invasive potential ant species, particularly microhabitats characterized by high human activities such as port areas, markets, domestic streets and residential areas.
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