DETERMINATION OF THE EVOLUTIONARY RELATIONSHIPS IN RATTUS SENSU-LATO (RODENTIA, MURIDAE) USING L1 (LINE-2) AMPLIFICATION EVENTS

We determined similar to 215 bp of DNA sequence from the 3'-untranslat ed region (UTR) of 240 cloned L1 (LINE-1) elements isolated from 22 sp ecies of Rattus sensu late and Rattus sensu stricto murine rodents. Th e sequences were sorted into different L1 subfamilies, and oligonucleo tides cognate to them were hybridized to genomic DNA of various taxa. From the distribution of the L1 subfamilies in the various species, we inferred the partial phylogeny of Rattus sensu late. The four Maxomys species comprise a well-defined clade separate from a monophyletic cl uster that contains the two Leopoldamys and four Niviventer species. T he Niviventer/Leopoldamys clade, in turn, shares a node with the clade that contains Berylmys, Sundamys, Bandicota, and Rattus sensu stricto . The evolutionary relationships that we deduced agree with and signif icantly extend the phylogeny of Rattus sensu lato established by other molecular criteria. Furthermore, the L1 amplification events scored h ere produced a unique phylogenetic tree, that is, in no case did a cha racter (a given L1 amplification event) appear on more than one branch . The lack of homoplasy found in this study supports the robustness of L1 amplification events as phylogenetic markers for the study of mamm alian evolution.