A taxonomic and evolutionary study of Aster section Biotia

In this dissertation I present the correct author citation for the combination Aster section Biotia, provide a disposition for all the names, and list all the known types of names attributed to taxa belonging in the section. In addition, I show that although historically over eighty species have been recognized in Aster section Biotia, the data support the acceptance of only seven species. One of these was the new species A. jonesiae, a Piedmont endemic of Alabama and Georgia, which I discovered and named during the course of my research.By statistical analyses, I show that Aster glomeratus is conspecific with A. schreberi, that A. commixtus is conspecific with A. spectabilis, and that A. mirabilis and A. jonesiae are distinct species. I present the first application of disjoint principal component analysis to vascular plant systematics in the examination of the status of A. commixtus, and I further demonstrate the use of the method in showing that A. chlorolepis is a good species and is almost certainly an autotetraploid derivative of A. divaricatus.Also in this thesis I introduce the new concept of retrogressive polyploidy, and I suggest that the hexaploids in Aster section Biotia arose from diploid and octoploid ancestors by this process of hybrid speciation.By means of isozyme and cladistic analyses I attempt to reconstruct the phylogeny of Aster section Biotia. From the analysis of isozyme data I find that A. mirabilis and A. jonesiae are genetically very similar, that A. divaricatus, A. chlorolepis, A. schreberi, and A. macrophyllus are closely related, and that A. furcatus is relatively distantly related to the other members of the group. Finally, using cladistic methods I show that A. divaricatus is likely to lie at or near the root of the phylogeny of Aster section Biotia and that section Biotia is probably not a monophyletic group.U of I OnlyETDs are only available to UIUC Users without author permissio