Systematic and evolutionary implications ofrbcL sequence variation in Rosaceae

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Abstract
The angiosperm family Rosaceae poses a number of noteworthy systematic problems as well as many questions concerning morphological and chromosomal evolution. Phylogenetic analysis ofrbcL gene sequences was performed to address systematic and evolutionary problems of Rosaceae. BothrbcL sequence variation and the presence of duplicated sequences near the 3' end ofrbcL were useful in determining phylogenetic relationships in this family. Analyses ofrbcL sequences indicate that there are groups of genera within Rosaceae comparable to the subfamilies Maloideae, Amygdaloideae, and Rosoideae, although the composition of each group differs from traditional circumscriptions. According to analysis ofrbcL data, Maloideae and Amygdaloideae each include additional taxa not normally associated with them. All members of Rosoideae withx= 9 are phylogenetically well separated from thex= 8 and 7 members of the subfamily. In addition, Spiraeoideae are not monophyletic but appear to consist of several distinct evolutionary lineages. TherbcL‐based phylogenies suggest that chromosome numbers are more reliable indicators of some generic alliances than the more commonly used fruit types. Sequence data are also useful in determining the alliances of several problematic genera, suggesting that the capsular and follicular‐fruited generaVauquelinia, Lindleya, andKageneckia(usually placed in Spiraeoideae) should be included in the pome‐fruited subfamily Maloideae, and thatQuillajais not a member of Rosaceae. Molecular data are consistent with several suggestions for the ancestral chromosome numbers and fruit types of Rosaceae, but do not support any one hypothesis for either. This study also suggests that the subfamily Maloideae may have descended from spiraeoid ancestors and that the pome is derived from follicular or capsular fruit types.
Funding Information
  • National Science Foundation (BSR 9007614)