Table 1. Description of the Four X-Y Gene Pairs and the PAR Marker Used in the Analyses.

^a For the four genes, the alignments include coding sequences of both X and Y copies in S. latifolia, S. dioica, and S. diclinis, and the orthologous sequence from a close outgroup (S. vulgaris or S. noctiflora). The values correspond to the number of sites with no gaps or ambiguous bases). Values in parentheses indicate the numbers of diverged sites

^b  DD44 is also single-copy in S. latifolia [20], but at least two copies are found in other Silene species, including S. dioica (V. Laporte, unpublished data) and other species (J. Ironside, Univ. of Birmingham, UK, unpublished data).In our S. dioica material, there are three tightly linked X-linked copies (B. Janousek, unpublished data). Thus this duplication does not affect our mapping conclusions