RETROTRANSPOSON MYS WAS ACTIVE DURING EVOLUTION OF THE PEROMYSCUS-LEUCOPUS-MANICULATUS COMPLEX

Mys is a retrovirus-like transposable element found throughout the gen us Peromyscus. Several mys subfamilies identified on the basis of rest riction site variation occur in more than one species. The distributio n of these subfamilies is consistent with the accepted species phyloge ny, suggesting that mys was present in the ancestor of Peromyscus and has been active through much of the evolution of this genus. Quantitat ive Southern blot analysis was used to examine the variability of subf amilies in P. leucopus and maniculatus. We found that subfamilies with phylogenetically narrow distributions were more variable in copy numb er both within and between species than subfamilies with a broader dis tribution. Taken together, our data suggest that mys has undergone mul tiple rounds of transposition since the peromyscine radiation, and tha t five subfamilies have been amplified during the evolution of the leu copus-maniculatus species complex.