Biogeography of T rimerotropis pallidipennis ( A crididae: O edipodinae): deep divergence across the A mericas

Abstract

Aim T rimerotropis pallidipennis represents a species complex of band‐winged grasshopper distributed over N orth and S outh A merica. Previous studies indicated a N orth A merican origin of the species and suggested that colonization of S outh A merica occurred during the P leistocene after the closure of the I sthmus of P anama. Here we use a phylogeographical approach in order to test different biogeographical scenarios and determine how many distinct units exist within the species complex. Location N orth and S outh A merica with specific emphasis on the A ndes mountains of S outh A merica. Methods We sequenced two mitochondrial and two nuclear genes for multiple specimens belonging to each taxonomic unit. Using the concatenated dataset and a coalescent‐based approach we estimated the phylogeny of the complex. In order to distinguish the different biogeographical and species delimitation hypotheses we constrained our dataset to different taxon sets and ran B ayesian analyses in * beast . Posterior probabilities and DensiTree plots allowed us to determine the best hypotheses. We used a molecular clock approach to correlate geological events with observed phylogenetic splits. Results All analyses indicate the existence of at least three distinct genetic lineages: T rimerotropis pallidipennis from N orth A merica, T rimerotropis ochraceipennis from C hile and an undescribed T rimerotropis species from A rgentina. The split between N orth and S outh A merican forms took place about 1.3 Ma, long after the I sthmus of P anama had been completed. Biogeographical analyses suggest a first dispersal event from N orth to S outh A merica. Subsequent dispersion and vicariance probably led to the differentiation of the endemics now found in C hile and A rgentina. Main conclusions We demonstrate the existence of three distinct genetic lineages in the T rimerotropis pallidipennis species complex. These lineages are also chromosomally differentiated as previous studies have indicated. Dispersion of T . pallidipennis from N orth to S outh A merica probably occurred during the early P leistocene, when climatic conditions were more suitable. Subsequent diversification in S outh A merica was the result of range expansion and vicariance, possibly in response to later P leistocene glaciations of the A ndes.

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