PROTEIN POLYMORPHISM IN ELIGMODONTIA-TYPUS - GENETIC-DIVERGENCE WITH OTHER PHYLLOTINE CRICETIDS

By means of gel electrophoresis of tissue extracts we have studied pro tein polymorphism in Eligmodontia typus. The analysis was performed on specimens from five population samples collected at different sites i n Patagonia (Argentina). Mean heterozygosity ((H) over bar) and propor tion of polymorphic loci (P) were determined on the basis of 19 loci. Considering all individuals as one sample, (H) over bar gave a value o f 0.16 and P was 70%. Although these values are much higher than those reported for most rodent species, they are very similar to those obta ined by us for four species of the genus Calomys and for Graomys grise oflavus. There is a striking genetic identity (I-N = 0.99) among popul ations from regions with different environmental conditions, indicatin g that the species possesses a common genic pool. Genetic distance wit h other species of the Phyllotini was estimated. D-N was lower between E. typus and Calomys (mean D-N = 0.88) than between E. typus and Grao mys griseoflavus (D-N = 1.01). The high morphological similarity betwe en these last two species, especially regarding those characters relat ed to desert life adaptation, could be assigned, at least in part, to convergent evolution.