Genomic inferences in a thermophilous grasshopper provide insights into the biogeographic connections between northern African and southern European arid-dwelling faunas

Aim Although thermophilous and arid-dwelling relict biotas constitute a singular component of European biodiversity of high conservation value, we still largely ignore their biogeographic history. In this study, we investigate the geographical diversification of the Maghrebian-Levantine crested grasshopper and its colonization of semiarid habitats of southeastern Iberia to gain insights into the historical processes underlying the biogeographic connections between northern African and southern European arid-dwelling faunas. Location Mediterranean region. Taxon Crested grasshoppers Dericorys millierei and Dericorys carthagonovae (Orthoptera: Dericorythidae). Methods We used genomic data (ddRAD-seq) to quantify the genetic structure of populations, infer the phylogenetic relationships among them, estimate divergence times, and elucidate the demographic processes accompanying the colonization of southeastern Iberia. Genomic-based inferences were interpreted in the light of eustatic sea-level reconstructions and species' range dynamics derived from palaeodistribution modelling at fine temporal resolution. Results Clustering analyses showed a strong genetic structure and phylogenomic inference revealed that Iberian populations are nested within a Maghrebian clade. Molecular dating analyses indicated that all lineages diverged during the Pleistocene (<1.6 Ma), with point estimates coinciding with glacial periods and the accompanying sea level drops. According to palaeodistribution modelling, the species experienced severe range contractions during the coldest stages of the Pleistocene. Main conclusions Our results indicate that the colonization of the Iberian Peninsula likely took place during the marked sea level drops characterizing the high-amplitude climatic oscillations of the late Quaternary (<0.5 Ma), which considerably reduced overseas distances between northern African and southern European landmasses and might have eased transmarine exchanges of terrestrial faunas. These findings emphasize the high relevance of the Maghreb region as a source of European thermophilous biotas and corroborate post-Messinian biogeographic connections between the two continents despite the barrier effect of the Mediterranean Sea.

Automated summary

This study investigated the biogeographic history of the Maghrebian-Levantine crested grasshopper and its colonization of semiarid habitats in southeastern Iberia using genomic data. The results showed genetic structure and phylogenetic relationships, with populations in Iberia nested within a Maghrebian clade. Molecular dating analyses suggested divergence during the Pleistocene and palaeodistribution modeling indicated range contractions during colder stages of the Pleistocene. The findings highlight the relevance of the Maghreb region as a source of European biodiversity and support biogeographic connections between northern Africa and southern Europe despite the barrier effect of the Mediterranean Sea.