CONICET | Buscador de Institutos y Recursos Humanos

Chromosomal inversions are known to play roles in adaptation and differentiation in many species.They involve clusters of correlated genes (i.e loci in linkage disequilibrium, LD) possibly associatedwith environmental variables. The grasshopper ?species complex? Trimerotropis pallidipenniscomprises several genetic lineages distributed from North to South America in arid and semi-aridhigh-altitude environments. The southernmost lineage, Trimerotropis sp., segregates for 4-7 putativeinversions that display clinal variation, possibly through adaptation to temperate environments. Weanalyzed chromosomal, mitochondrial and genome-wide single nucleotide polymorphism (SNP) datain 19 Trimerotropis sp. populations mainly distributed along two altitudinal gradients (MS and Ju).Populations across Argentina comprise two main chromosomally and genetically differentiatedlineages: one distributed across the southernmost border of the ?Andes Centrales?, adding evidencefor a differentiation hotspot in this area; and the other widely distributed in Argentina. Within thelatter, network analytical approaches to LD found three clusters of correlated loci (LD-clusters), withinversion karyotypes explaining >79% of the genetic variation. Outlier loci associated withenvironmental variables mapped to two of these LD-clusters. Furthermore, despite the complexgeographic history indicated by population genetic analyses, the clines in inversion karyotypes haveremained stable for more than 20 generations, implicating their role in adaptation and differentiationwithin this lineage. We hypothesize that these clines could be the consequence of a coupling betweenextrinsic postzygotic barriers and spatially varying selection along environmental gradients resultingin a hybrid zone. These results provide a framework for future investigations about candidate genesimplicated in rapid adaptation to new environments.