CYTOGENETICS AND SYSTEMATICS OF THE RODENT GENUS GERBILLURUS

Chromosomal G- and C-band data for all four species of the genus Gerbillurus (paeba, vallinus, setzeri, tytonis) document extensive variation both within and among species when using Tatera as an outgroup. G. setzeri and G. vallinus have 2n = 60 karyotypes and share several derived chromosomal conditions. They probably shared a common ancestor after divergence from G. paeba and G. tytonis. Although G. paeba and G. tytonis have similar karyotypes, the G-band data suggest that these two species shared only plesiomorphic states for their chromosomal characters. The presence of interstitial insertions of homogeneously staining chromosomal material in this genus is reported. It is concluded that these regions result from gene amplification, a phenomenon rarely encountered in natural populations.