Fig. 1.

Summary of gene movement to and from the Y chromosome and tests of selection for the genes and species included in this study. Only one of the three tree topologies used for our analysis is depicted here (see Materials and Methods). Genes moving onto the Y chromosome are listed above the branches on which they were acquired by the Y chromosome. Genes lost from the Y chromosome are listed below the branch in which the gene was lost. Although all genes were subject to all of the described PAML model comparisons, we only summarized the significant results here: ^aSignificant branch model comparison, ^bsignificant M7–M8 comparison, ^csignificant branch-site model comparison. *Note that the placement of CCY on this branch is somewhat uncertain (Koerich et al. 2008).