Low substitution rates in mitochondrial DNA in Mediterranean carabid beetles

The estimation of DNA substitution rates requires calibration with the geological events which caused the separation of populations. We used the disintegration of the landbridges between Morocco and Gibraltar as well as the Balearics and Spain at the end of the Messinian event (5.3 myr) in order to calibrate the DNA sequence data of the NADH-dehydrogenase subunit 1 (ND1) in West Mediterranean Carabus species. The rates of molecular evolution we found are much lower than those reported in the literature and also vary from species to species. Therefore, in insects the calculation of divergence periods using a constant 2% substitution rate per myr is questionable.