Adaptation to new environments is an important issue for invasive species as colonization depends on evolvability in their new distribution range. Here, we considered the case of the whitefly Bemisia tabaci MEAM 1 (Gennadius) (Hemiptera: Aleyrodidae), a pest that has recently invaded Colombia and where thermal adaptation has been proposed to explain its colonizing ability. An experimental evolution study was conducted to assess the evolutionary potential of B. tabaci in relation to its upper thermal limits, to explain its rapid adaptation during post-invasion periods. Selection for hardening capacity was conducted in four whitefly populations. We measured thermal responses in relation to fitness components (survival, fecundity, and viability) for 5-7 generations under a strong selection regime. Heat hardening responded rapidly in both sexes. This was expressed as an increase in survival, but not in fecundity or viability. These results suggest that thermal responses for heat hardening are not correlated and evolve independently. Increased survival after few generations of selection points to high adaptive potential in this insect, which leads to rapid post-invasion adaptation. Our study can help to predict population responses to environmental change and explain the colonizing ability of this pest.

There is an increasing evidence that populations of ectotherms can diverge genetically in response to different climatic conditions, both within their native range and (in the case of invasive species) in their new range. Here, we test for such divergence in invasive whitefly Bemisia tabaci populations in tropical Colombia, by considering heritable variation within and between populations in survival and fecundity under temperature stress, and by comparing population differences with patterns established from putatively neutral microsatellite markers. We detected significant differences among populations linked to mean temperature (for survival) and temperature variation (for fecundity) in local environments. A Q ST À F ST analysis indicated that phenotypic divergence was often larger than neutral expectations (Q ST > F ST ). Particularly, for survival after a sublethal heat shock, this divergence remained linked to the local mean temperature after controlling for neutral divergence. These findings point to rapid adaptation in invasive whitefly likely to contribute to its success as a pest species. Ongoing evolutionary divergence also provides challenges in predicting the likely impact of Bemisia in invaded regions.

There is a wealth of evidence demonstrating that the Andean uplift has promoted allopatric diversification in a wide range of taxa (Hoorn et al., 2010;Pérez-Escobar et al., 2017;Salgado-Roa et al., 2018). These mountains reach their maximum complexity in northern South America (Colombia), forming a branch of three parallel mountain ranges separating flora and fauna in a North-South manner

The leaf-cutting ant, Atta cephalotes L. (1758), is a major herbivore with great economic impact in the Neotropics. Because of its broad range and human-mediated dissemination, the ecology of this ant has received considerable attention; however, questions concerning its population genetics, dispersal, and social structure remain unexplored. Here, we aimed to identify and provide information on molecular and statistical performance of a suite of polymorphic microsatellite markers for A. cephalotes while demonstrating their utility for further genetic studies. We designed primer sequences targeting thousands of microsatellite loci and then screened 30 of these for amplification and polymorphism. Fifteen of these loci were selected and used to evaluate their polymorphism using 74 ants sampled from 15 different nests of the same location. This set of 15 loci exhibited variation of 2–20 alleles, with a mean heterozygosity of 0.57. All loci followed Hardy–Weinberg expectations with no evidence of linkage disequilibrium, while two loci showed evidence of null alleles. Our preliminary analysis suggested substantial nest differentiation with no population viscosity within the sampled location, as well as colonies with multiple queens (polygyny) and paternity (polyandry). Our newly identified microsatellites have proven to be highly informative to investigate gene flow, social structure and reproduction of this key agricultural pest.

Neotropical diversification by the Andean uplift is typically addressed on a large evolutionary scale (e.g. speciation), even though many species are still distributed in both sides of the mountains. The three parallel mountain ranges in the northern Andes (Colombia) impose a major geographical barrier to species' migration from South to Central America. How important these barriers are for conspecific diversification of cross-Andean species such as the leaf-cutting ants remains largely unknown. To answer this question, we studied the mtCOI gene of Atta cephalotes, the most widely distributed leaf-cutting ant species. Our hierarchical analyzes evidenced substantial genetic structure among regions and populations, suggesting a more complex biogeographical history of Andean populations than previously thought. These mountains seem to isolate Central American and Western Colombian populations from the rest of A. cephalotes in South America. Population and migration modelling are consistent with the origin of this species in South America and a major role of the Eastern cordillera as a geographical barrier to historical gene flow, restricting dispersion from north to south. These findings provide insights into the role of the Andean uplift as barrier to gene flow and, eventually, implications for monitoring and designing management strategies for leaf-cutting ants.