KARYOTYPE AND GENETIC EVOLUTION IN SPECIATION OF SUBTERRANEAN MOLE-RATS OF THE GENUS SPALAX IN TURKEY

Karyotype (2n) and allozyme diversity at 37 gene loci were determined in 69 subterranean mole rats in Turkey belonging to the two superspeci es: the ancestor Spalax leucodon (n = 55; 20 populations) and the desc endant S. ehrenbergi (n = 14; four populations. We identified remarkab le variation of diploid chromosome numbers in the S. leucodon superspe cies: 2n = 38, 40, 50, 54, 60 and 62; and in the S. ehrenbergi supersp ecies: 2n = 52, 56 and 58. Genetic diversity indices were low on avera ge in both S. leucodon and S ehrenbergi superspecies: Allele diversity , A = 1.081 adn 1.074; polymorphism, P-5% = 0.077 and 0.068; heterozyg osity, H = 0.038 and 0.027; and gene diversity, H-e = 0.038 and 0.034, respectively. H ranged from 0 in mesic or semimesic regions to 0.088 in arid Anatolia. We consider the populations with different diploid c hromosome numbers, 2n, as good biological species. Karyotypic diversit y may mark extensive ecological speciation. Nei's genetic distances, D (average 0.174, rang 0.002-0.422) and ecogeographical criteria sugges t that almost each population may represent a different biological spe cies, but critical future testing is necessary to support this claim. Karotypes and allozymes are nonrandomly distributed across Turkey, dis playing remarkable correlations with climatic and biotic factors. Both 3n and H are significantly correlated with aridity stress (2n/rainfal l, r(6) = -0.74; P < 0.001), and in our region also with climatic unpr edictability. These results support the niche-width genetic variation hypothesis in space and time. Climatic selection in Turkey appears to be a major architect of karyotype and genetic (allozyme) diversity and divergence in mole rat evolution, in both speciation and adaptation.