Genetic and morphometric evidence of introgression between two species of moles (Insectivora : Talpa europaea and Talpa romana) in central Italy

Allozyme and morphometric variation was studied in two populations of moles , Talpa europaea and T. romana, in an area of sympatric occurrence (Palazzo , near Assisi, central Italy) located along the known parapatric contact bo undary. The electrophoretic analysis revealed 36 moles characterized by a g enome of T. europaea, and 29 moles with a genome of T. romana. The extensio n of the overlap zone was c. 2 km along the north-south direction. Fourteen specimens recognized as T. europaea had an Adn allele typical of T. romana , while two specimens identified as T. romana were characterized by two all eles (at the Adh and Sdh loci) previously found only in T. europaea. The sk ulls of the specimens with introgressed alleles showed features intermediat e between those typical of T. romana and I: europaea. However, the intermed iate skull shape of the introgressed specimens did not correspond to an int ermediate size between T. romana and T. europaea. The occurrence of individ uals with introgressed alleles, and the lack of F-1 hybrids or backcrossed individuals suggest that at present free interbreeding between the two spec ies is unlikely, but that hybridization and backcrossing has occurred, prob ably when the species first came into contact.