Deep divergence and evidence for translocations between Iranian and European populations of the alfalfa weevil (Coleoptera: Curculionidae) based on mitochondrial DNA.
The alfalfa weevil (Hypera postica (Gyllenhal): Coleoptera: Curculionidae) is an invasive pest of alfalfa (Medicago sativa Linnaeus; Fabaceae) in the Holarctic region. Across the wide geographic distribution of the species different local adaptions have been observed. Further, several distinct mitochondrial lineages have been discovered, which have been treated as western and Egyptian/eastern strains. However, our knowledge of the biogeography of H. postica is largely limited to North American and Japanese populations. We sampled the species from four locations in Iran and two countries in Europe (Poland and Czech Republic) and sequenced the mitochondrial COI gene to detect patterns of mitochondrial DNA divergence among Iranian and European strains. We detected two groups separated by a deep molecular split, even justifying the distinction of two molecular operational taxonomic units. Joint analyses with previously published sequences suggest that the European samples may represent the western strain, whereas both the western and Egyptian/eastern strains can be found in Iran. This distribution of genetic lineages may be the result of human-mediated translocations. The directionality, however, cannot be inferred. Our data suggest that translocations may have led to the coexistence of multiple H. postica lineages in some parts of the world, e.g., Iran. We discuss these findings against the background of the current taxonomy of H. postica.