Assortative mating between chromosome forms of the mole rat, Spalax ehrenbergi

Females of two parapatric chromosomal forms (2n=52 and 2n=58) of the fossorial mole rat, Spalax ehrenbergi, in Israel, were tested for mate selection between two alternative, a homo- and a heterochromosomal, males. Estrous females significantly preferred the male of their own chromosomal form, on the basis of several behavioural criteria. The evolutionary significance of the positive assortative mating found, lies presumably in reinforcing reproductive isolation between the chromosome forms, thereby contributing to finalize speciation.