An analysis of systematic and phyletic relationships within the Baccharidinae (Asteraceae: Astereae) /
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| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1991.
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| Subjects: | |
| Online Access: | Link to OAKTrust copy |
| Abstract: | The two primary objectives of this study were to utilize cpDNA and nuclear rDNA restriction site mutation analyses to (1) construct a phylogeny including the genera of the Baccharidinae and closely related genera, and use that phylogeny to examine the evolution of the woody condition and sexual expression within the group, and (2) test for the existence of a hybridization zone between Baccharis neglecta and B. halimifolia. Chloroplast DNA data provided the basis for the phylogeny of the Baccharidinae genera and three other closely related genera: Aster. Erigeron, and Conyza. The parsimony-based analysis suggests that South American Conyza spp. should be included in subtribe Baccharidinae, and that the Baccharidinae consists of two major clades. One includes the genera Heterothalamus and Archibaccharis while the other includes South American Conyza notobellidastrum. Baccharis, and Baccharidastrum. The data suggest that the subtribe itself is basally woody and there have been some reversions to the herbaceous growth habit within the Baccharidinae. The phylogeny also suggests that monoecy has been derived from dioecy in at least two instances within the genus Baccharis: once in B. monoica and a second time in Baccharidastrum which has recently been placed into sect. Baccharidastrum of the genus Baccharis. Chloroplast DNA as well as nuclear ribosomal DNA restriction site analyses and length polymorphisms were used to verify that B. neglecta and B. halimifolia do hybridize in a region of overlapping distributions that runs through Brazos County, Texas, with B. neglecta being the maternal parent. There has apparently been backcrossing into both parental species. |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Botany." |
| Physical Description: | ix, 83 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references. |