Fig. 1.

Phylogeny of rodents included in the analysis as per the consensus of data from Steppan et al. (77) and Smith and Patton (76). The numbers and arrows indicate estimated times of divergence in million years according to Steppan et al. (77). The color gray delineates Sigmodontinae affected by the L1 extinction event ∼8.8 million years ago (32). Basal species S. hispidus either diverged before L1 extinction occurred or regained L1 activity through mutation or recombination, but has no B1 SINE activity. The ERV mysTR expanded after the ancestor of Mus diverged.