Pleistocene climatic oscillations influenced the emergence of geographically widespread and restricted genetic lineages in an Andean grasshopper species group

The grasshopper Trimerotropis pallidipennis species complex is distributed across arid and semi-arid environments from North to South America, reaching high altitudes along the Andes Mountain range. Currently, there are four valid species of Trimerotropis in South America. However, some species were found to comprise several genetic lineages. Here, we describe the genetic structure, lineage diversification, and environmental requirements within the Trimerotropis species complex in South America based on sequences from the mitochondrial COI gene, 4048 single nucleotide polymorphisms, and ecological niche modelling. The analyses revealed the existence of at least five lineages: two with a restricted geographical distribution and three with a very wide one. The results provide evidence that glacial cycles promoted not only the presence of refuge areas but also the isolation of widely distributed lineages on the eastern and western sides of the southern Andes, potentially driving the emergence of the Trimerotropis sp. lineage, which can tolerate more temperate habitats. Our results provide evidence for the effects of Pleistocene climatic changes on the diversification history of a South American grasshopper species complex.