Genomic exploraon approaches reveal hybrid zones and hidden biological units in an Andean grasshopper species group with chromosomal inversions

CONFALONIERI, VIVIANA A; GANDINI, LUCIANO M; CASTILLO ELIO R; CIGLIANO, MARIA MARTA; GUZMAN N. V.

Merida

Simposio; XIV International Congress of Orthopterology 2023; 2023

SouthAmerica harbors five of the world's biodiversity hotspots and itsbiodiversity is likely to have been modeled by geological events,marine introgressions and climatic oscillations. Among the former,the uplift of the Andes (23 to 5 My) has been associated with themost rapid and diverse radiations on Earth. TrimerotropisStål is a grasshopper genus distributed across the Americas fromCanada to Chile and Argentina with more than 40 species inhabitingdry and temperate regions. In South America it inhabits high-altitudeenvironments along the Andes Mountain range. The reported number ofspecies in this subcontinent has varied over the last 160 years withonly three species being finally recognized. However, as some of themwere found to comprise several genetic lineages, the South Americanrepresentatives of the genus are now considered as a complex (i.e.“T.pallidipenniscomplex”). The Trimerotropissp. lineage is distributed in Argentina and segregates for four toseven chromosomal inversions that display clinal variation.Usinggenome wide single nucleotide polymorphisms (SNPs) and networkanalytical approaches to find loci in linkage disequilibrium (LD),three clusters of correlated loci were found to be associated withinversion karyotypes; furthermore, non-neutral loci associated withenvironmental variables mapped to two of these LD-clusters. Thisresult, together with the finding that inversion frequencies remainedstable for more than 20 generations, led to postulate that: i)inversions play a role in the adaptation of Trimerotropissp populations to new environments; and ii) the clines could be theconsequence of a coupling between extrinsic postzygotic barriers andspatially varying selection along environmental gradients, resultingin a hybrid zone between Trimerotropissp and a different genetic lineage. To further investigate thissubject, we expanded the geographic scope in relation to previousanalyses, including new samples from Chile, Bolivia, Perú, as wellas samples from a new altitudinal cline in Argentina. We analyzed thegenetic structure, lineage diversification and environmentalrequirements within the entire Trimerotropiscomplexand its association with geography and Pleistocene glaciations, usingSNPs and ecological niche modeling. The analyses revealed theexistence of at least five lineages, two of them with a restrictedand the other three with a very wide geographic distribution. Glacialcycles most probably isolated widely distributed lineages on theeastern and western sides of the southern Andes, potentially drivingthe emergence of the Trimerotropissp. lineage, which can tolerate more temperate habitats. One of theaforementioned restricted genetic lineages have been most probablyisolated in a valley refuge at 32°S latitude in the southern Andesduring the last Patagonian glaciations, thereby differentiating fromTrimerotropissp.and giving rise after secondary contacts to an hybrid zone. Ourresults provide evidence for the effects of Quaternary climaticchanges, refugial areas and chromosomal inversions on thediversification history of a South American grasshopper speciescomplexp { margin-bottom: 0cm; direction: ltr; color: #000000; text-align: justify; orphans: 2; widows: 2 }p.western { font-family: "Times New Roman", serif; font-size: 8pt; so-language: es-MX }p.cjk { font-family: "Batang", "Arial Unicode MS"; font-size: 8pt }p.ctl { font-family: "Times New Roman", serif; font-size: 8pt; so-language: ar-SA }a:visited { color: #800080 }a.western:visited { so-language: en-US }a.cjk:visited { so-language: zh-CN }a.ctl:visited { so-language: hi-IN }a:link { color: #0000ff }