Figure 1

Sampling locations of C. aspersum throughout the western Mediterranean basin. Population numbers are those given in additional file 1. Sample site symbols and colours indicate the mtDNA lineage of the population: pink for east type, green for west type (including Z). Grey areas represent microplates drifted from Oligocene: GK: Great Kabylia, PK: Lesser Kabylia, Ri: Rif Cordillera, Be: Betic range, Ba: Balearic Islands, Sa: Sardinia, Co: Corsica, Si: Sicilia, Ca: Calabria. The dotted line throughout Europe shows the -1°C January isotherm line during the LGM [18]. Dotted curves in Iberia represent seven putative terrestrial refugia [69]. Putative geographical barriers (Moulouya River basin, Edough Peninsula, Atlas and Tell system) and contact zones (black arrows in opposite direction in Kabylia, Galicia and Italia) suggested in the present paper are also reported.