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A systematic study of Machaeranthera...

Morgan, David Randal.

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A systematic study of Machaeranthera (Asteraceae) and related groups using restriction analysis of chloroplast DNA and a taxonomic revision of Machaeranthera section Psilactis.

Record Type:	Electronic resources : Monograph/item
Title/Author:	A systematic study of Machaeranthera (Asteraceae) and related groups using restriction analysis of chloroplast DNA and a taxonomic revision of Machaeranthera section Psilactis./
Author:	Morgan, David Randal.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 1990,
Description:	196 p.
Notes:	Source: Dissertation Abstracts International, Volume: 51-10, Section: B, page: 4678.
Contained By:	Dissertation Abstracts International51-10B.
Subject:	Botany. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=9105619

A systematic study of Machaeranthera (Asteraceae) and related groups using restriction analysis of chloroplast DNA and a taxonomic revision of Machaeranthera section Psilactis.
Morgan, David Randal.

A systematic study of Machaeranthera (Asteraceae) and related groups using restriction analysis of chloroplast DNA and a taxonomic revision of Machaeranthera section Psilactis. - Ann Arbor : ProQuest Dissertations & Theses, 1990 - 196 p.

Source: Dissertation Abstracts International, Volume: 51-10, Section: B, page: 4678.

Thesis (Ph.D.)--The University of Texas at Austin, 1990.

Restriction site analysis of chloroplast DNA and ribosomal RNA genes was performed on species of Machaeranthera (Asteraceae: Astereae) and additional related genera. Restriction site data was analyzed using Dollo parsimony, Wagner parsimony, bootstrap analysis, and maximum likelihood. Based on chloroplast DNA, a monophyletic Machaeranthera alliance can be circumscribed which includes several segregates of Haplopappus, a group of genera with a basic chromosome number of x = 6, and all taxa historically associated with Machaeranthera except section Psilactis. The Machaeranthera alliance consists of no species with a basic chromosome number greater than x = 6, and includes a large proportion of the taxa of the tribe Astereae with basic chromosome numbers of x = 4, 5, and 6. Among several well-supported monophyletic groups, one is composed entirely of x = 6 genera, but does not include the two x = 6 genera Xylorhiza and Pyrrocoma. Unexpected results were found in two groups, with chloroplast DNA indicating alliances of Machaeranthera section Arida with Pyrrocoma and of Machaeranthera sections Machaeranthera and Hesperastrum with Oonopsis. Contradictory data from chloroplast DNA and ribosomal RNA genes concerning alliances between three species (Machaeranthera gypsitherma, M. viscida, and M. heterophylla) and M. section Blepharodon suggest the possible occurrence of ancestral hybridization or introgression. Chloroplast DNA and ribosomal RNA gene data strongly support a monophyletic group consisting of Machaeranthera section Psilactis and several species of Aster separate from the Machaeranthera alliance. Of interest is the specific relationship of the x = 4 species of section Psilactis with the x = 5 species of Aster subgenus Oxytripolium and the exclusion of the x = 9 species of both groups from this alliance. Ribosomal RNA gene data does not ally these x = 4 and x = 5 species but supports the inclusion of subgenus Oxytripolium in Aster and the traditional definition of section Psilactis and x = 4 and x = 9 species. On the basis of chloroplast DNA, ribosomal RNA genes, and morphological similarities with Aster, section Psilactis is removed from Machaeranthera and re-established as a genus. Psilactis mexicana is submerged in P. gentryi, reducing the number of species in the group from seven to six.Subjects--Topical Terms:

516217
Botany.

A systematic study of Machaeranthera (Asteraceae) and related groups using restriction analysis of chloroplast DNA and a taxonomic revision of Machaeranthera section Psilactis.
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035 $a (MiAaPQ)AAI9105619
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100 1 $a Morgan, David Randal. $3 3350471
245 1 2 $a A systematic study of Machaeranthera (Asteraceae) and related groups using restriction analysis of chloroplast DNA and a taxonomic revision of Machaeranthera section Psilactis.
260 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 1990
300 $a 196 p.
500 $a Source: Dissertation Abstracts International, Volume: 51-10, Section: B, page: 4678.
500 $a Supervisor: Beryl B. Simpson.
502 $a Thesis (Ph.D.)--The University of Texas at Austin, 1990.
520 $a Restriction site analysis of chloroplast DNA and ribosomal RNA genes was performed on species of Machaeranthera (Asteraceae: Astereae) and additional related genera. Restriction site data was analyzed using Dollo parsimony, Wagner parsimony, bootstrap analysis, and maximum likelihood. Based on chloroplast DNA, a monophyletic Machaeranthera alliance can be circumscribed which includes several segregates of Haplopappus, a group of genera with a basic chromosome number of x = 6, and all taxa historically associated with Machaeranthera except section Psilactis. The Machaeranthera alliance consists of no species with a basic chromosome number greater than x = 6, and includes a large proportion of the taxa of the tribe Astereae with basic chromosome numbers of x = 4, 5, and 6. Among several well-supported monophyletic groups, one is composed entirely of x = 6 genera, but does not include the two x = 6 genera Xylorhiza and Pyrrocoma. Unexpected results were found in two groups, with chloroplast DNA indicating alliances of Machaeranthera section Arida with Pyrrocoma and of Machaeranthera sections Machaeranthera and Hesperastrum with Oonopsis. Contradictory data from chloroplast DNA and ribosomal RNA genes concerning alliances between three species (Machaeranthera gypsitherma, M. viscida, and M. heterophylla) and M. section Blepharodon suggest the possible occurrence of ancestral hybridization or introgression. Chloroplast DNA and ribosomal RNA gene data strongly support a monophyletic group consisting of Machaeranthera section Psilactis and several species of Aster separate from the Machaeranthera alliance. Of interest is the specific relationship of the x = 4 species of section Psilactis with the x = 5 species of Aster subgenus Oxytripolium and the exclusion of the x = 9 species of both groups from this alliance. Ribosomal RNA gene data does not ally these x = 4 and x = 5 species but supports the inclusion of subgenus Oxytripolium in Aster and the traditional definition of section Psilactis and x = 4 and x = 9 species. On the basis of chloroplast DNA, ribosomal RNA genes, and morphological similarities with Aster, section Psilactis is removed from Machaeranthera and re-established as a genus. Psilactis mexicana is submerged in P. gentryi, reducing the number of species in the group from seven to six.
590 $a School code: 0227.
650 4 $a Botany. $3 516217
690 $a 0309
710 2 $a The University of Texas at Austin. $3 718984
773 0 $t Dissertation Abstracts International $g 51-10B.
790 $a 0227
791 $a Ph.D.
792 $a 1990
793 $a English
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=9105619