Polymorphism and divergence at the 5' flanking region of the sex- determining locus, Sry, in mice

We have investigated patterns of evolution in the nonrecombining portion ofthe Y chromosome in mice by comparing levels of polymorphism within Musdomesticus with levels of divergence between M. domesticus and M. spretus.A 1,277-bp fragment of noncoding sequence flanking the sex determininglocus (Sry) was PCR amplified, and 1,063 bases were sequenced and comparedamong 20 M. domesticus and 1 M. spretus. Two polymorphic base substitutionsand two polymorphic insertion/deletion sites were identified within M.domesticus; nucleotide diversity was estimated to be 0.1%. Divergencebetween M. domesticus and M. spretus for this region (1.9%) was slightlylower than the average divergence of single-copy nuclear DNA for thesespecies. Comparison of levels of polymorphism and divergence at Sry withlevels of polymorphism and divergence in the mitochondrial DNA controlregion provided no evidence of a departure from the expectations of neutralmolecular evolution. These findings are consistent with the presumed lackof function for much of the Y chromosome.