Molecular, morphological and ontogenetic evaluation of relationships and evolution in the Rosaceae

grantor: University of TorontoPhylogenetic relationships are hypothesized for the Rosaceae using comparative analyses of floral ontogeny, and data sets comprising non-molecular and molecular ('ndhF, rbc'L, nrITS) characters. Forty-three genera, from all four subfamilies, and 16 of 17 tribes, are represented in non-molecular and chloroplast DNA data sets, as well as two outgroup genera from the Rhamnaceae ('Ceanothus' and 'Rhamnus'). The nrITS data are restricted to Rosoideae and Maloideae, while floral ontogeny was examined in 14 genera from the Maloideae, Prunoideae, and Spiraeoideae. Comparative analyses of floral ontogeny and mature morphology support the monophyly of an expanded Prunoideae that includes 'Exochorda'. Comparative analyses of floral ontogeny in four spiraeoid genera, and mature morphology in an additional six genera, support the polyphyly of the subfamily and implicate some members in the origin of the Maloideae. Comparative analyses of floral ontogeny and mature morphology in seven Maloideae genera demonstrate the developmental basis for syncarpy, epigyny and other variations in mature maloid flowers. Ontogenetic data were also used to determine the homology of a number of micromorphological characters used in the non-molecular cladistic analysis. Non-molecular data from a number of sources are used to infer a phylogeny for the Rosaceae. The resulting sixteen trees are similar in topology to previous molecular analyses, but are poorly supported and conflict significantly with molecular data in congruence tests. Sequence data from the chloroplast gene ' ndhF' results in well-resolved and well-supported trees that are almost identical to, and highly congruent with, those obtained form 'rbc'L sequences. To achieve an estimate of Rosaceae phylogeny from all currently available data the non-molecular data were combined with binary data representing the individual topologies obtained from three molecular data sets (' ndhF, rbc'L, and nrITS). The four trees obtained from these combined data did not differ from the non-molecular phylogeny, and showed increased support for several nodes. One of these trees was used to map the evolution of Rosaceae chromosome number, fruit type, ovary, and ovule morphology. The evolution of these characters, together with a preliminary analysis of biogeography, are used to posit hypotheses concerning the origin of the Maloideae.Ph.D