Cladistic analyses of molecular (ndhF, rbcL: Morgan et al. 1994, nrITS: Campbell et al. 1995) and non-molecular data place four genera (Kageneckia, Lindleya, Porteranthus, and Vauquelinia) at the base of an enlarged Maloideae clade. These four genera were previously ascribed to the polyphyletic assemblage "Spiraeoideae".
Results from ndhF, non-molecular, and rbcL analyses place
other members of the "Spiraeoideae" (e.g. Physocarpus)
as sister taxa to the enlarged Maloideae clade.
particularly early gynoecium and ovule development, in Vauquelinia
and Physocarpus (Evans
and Dickinson 1999) is quite similar to that observed in the Maloideae
(Evans and Dickinson unpublished data).
The inclusion of Porteranthus at the base of the Maloideae clade
provides additional evidence for the origin of the subfamily by a polyploidization
event (x=18?) within the "Spiraeoideae," followed by
reduction in the number of chromosomes (x=15, 17).
Non-molecular data (e.g. morphology) may be encoded by both maternal and paternal genomes.
Thus the alternative hypothesis (ancient hybridization between amygdaloid and spiraeoid ancestors) cannot be rejected on the basis of available evidence.
Investigate the nuclear encoded gene Granule Bound Starch Synthase (GBSSI: "waxy") within a large number of Rosaceae and outgroup genera:
Preliminary results (Evans et al. in prep) demonstrate multiple copies of the "waxy" gene in the Rosaceae
Determining the extent of copy number within each subfamily may provide additional molecular evidence for evolution within the Rosaceae, particularly with respect to the origin of the Maloideae
Investigation of a number of putative outgroups may help determine the group(s) that are most closely related to the Rosaceae
All photographs on these pages copyright © Rodger Evans 1999.
© 1999 Botany Department, University of Toronto.Please send your comments to email@example.com; last updated 1-November-99