A MAJOR SATELLITE DNA FROM THE SOUTH-AMERICAN RODENTS OF THE GENUS CTENOMYS - QUANTITATIVE AND QUALITATIVE DIFFERENCES IN SPECIES WITH DIFFERENT GEOGRAPHIC-DISTRIBUTION

The quantity and quality of the major satellite DNA present in South A merican rodents of the genus Ctenomys were analyzed in various species of the genus. The quantity was analyzed by genomic DNA hybridization with sequences of this-major satellite DNA, in a dot-blot experiment. The quality was analyzed by hybridization of genomic DNA digested with restriction endonucleases, with sequences of this major satellite DNA , as well, in Southern-blot experimens. Quantitative and qualitative a nalyses were correlated with the geographic distribution of these spec ies, According to the dot-blot analysis performed under high-stringenc y conditions, Ctenomys species were classified in three groups contain ing none, low, and high amounts of this Ctenomys satelite DNA, respect ively. The first group comprises only C. opimus. The second group comp rises C. cf. perrensi, C. tuconax, and C. occultus. The last group inc ludes C. mendocinus, C. porteousi, C. azarae, C. australis, and C. tal arum. C. latro appears closely related to this last group but it shows some differences on its own. According to the quality of satellite Ct enomys DNA, Ctenomys species belonging to the last group are closely r elated, and all but one have a distinctive geographic distribution sou th of the 30-degrees-S latitude. In contrast, species of the second gr oup seem to be more distantly related and all were found north of the 30-degrees-S latitude, as is also the case for C. opimus.