TRACING PATERNAL ANCESTRY IN MICE, USING THE Y-LINKED, SEX-DETERMINING LOCUS, SRY

The molecular evolution of mammalian Y-linked DNA sequences is of spec ial interest because of their unique mode of inheritance: most Y-linke d sequences are clonally inherited from father to son. Here we investi gate the use of Y-linked sequences for phylogenetic inference. We desc ribe a comparative analysis of a 515-bp region from the male sex-deter mining locus, Sry, in 22 murine rodents (subfamily Murinae, family Mur idae), including representatives from nine species of Mus, and from tw o additional murine genera-Mastomys and Hylomyscus. Percent sequence d ivergence was <0.01% for comparisons between populations within a spec ies and was 0.19%-8.16% for comparisons between species. Our phylogene tic analysis of 12 murine taxa resulted in a single most-parsimonious tree that is highly concordant with phylogenies based on mitochondrial DNA and allozymes. A total evidence tree based on the combined data f rom Sly, mitochondrial DNA, and allozymes supports(1) the monophyly of the subgenus Mus, (2) its division into a Palearctic group (M. muscul us, M. domesticus, M. spicilegus, M. macedonicus, and M. spretus) and an Oriental group (M. cookii, M. cervicolor; and M. caroli), and (3) s ister-group relationships between M. spicilegus and M. macedonicus and between M. cookii and M. cervicolor. We argue that Y-chromosome DNA s equences represent a valuable new source of characters for phytogeneti c inference.