Tempo and mode of concerted evolution in the L1 repeat family of mice

A 300-bp DNA sequence has been determined for 30 (10 from each of threespecies of mice) random isolates of a subset of the long interspersedrepeat family L1. From these data we conclude that members of the L1 familyare evolving in concert at the DNA sequence level in Mus domesticus, Muscaroli, and Mus platythrix. The mechanism responsible for this phenomenonmay be either duplicative transposition, gene conversion, or a combinationof the two. The amount of intraspecies divergence averages 4.4%, althoughbetween species base substitutions accumulate at the rate of approximately0.85%/Myr to a maximum divergence of 9.1% between M. platythrix and both M.domesticus and M. caroli. Parsimony analysis reveals that the M. platythrixL1 family has evolved into a distinct clade in the 10-12 Myr since M.platythrix last shared a common ancestor with M. domesticus and M. caroli.The parsimony tree also provides a means to derive the average half-life ofL1 sequences in the genome. The rates of gain and loss of individual copiesof L1 were estimated to be approximately equal, such that approximatelyone-half of them turn over every 3.3 Myr.