Electronic Theses and Dissertations

Ramhari Thapa

Date

2019

Document Type

Dissertation

Degree Name

Doctor of Philosophy

Department

Biology

Committee Chair

Dr. Randall J. Bayer

Committee Member

Dr. Jennifer R. Mandel

Committee Member

Dr. Thomas Sutter

Committee Member

Dr. Duane McKenna

Committee Member

Dr. James Moore

Abstract

Antennaria are dioecious perennial herbs distributed mainly in the Holarctic Region with their major center of diversity in the Rocky Mountains of Western North America. The genus, which consists of 34 known sexual diploid/tetraploid species and at least five polyploid agamic complexes has a complex evolutionary history due to dioecism, excessive polyploidy, and the evolution of polyploid agamic complexes. In this study, a phylogenetic reconstruction of the 34 sexually reproducing Antennaria species using a target enrichment method, development of microsatellite markers for the genus, and study of the genetic diversity, population structure, and estimation of ancestry was carried out in one of the most morphologically diverse polyploid agamic complexes, A. rosea. Phylogenomic data from 756 nuclear loci recovered Antennaria as a monophyletic group except for the long-disputed species, A. linearifolia. Antennaria was further resolved into three distinct, major lineages. Results from morphological character mapping of 12 taxonomically important characters elucidated evolutionary trends for different clades. Antennaria, based on estimations of ancestral geographic ranges, most likely evolved in Rocky Mountain region including the Vancouverian province around 5.8 MYA. Subsequent dispersals of Antennaria into the Arctic and Appalachian provinces, Canadian provinces, and Eurasia took place roughly 3.2 MYA, 2.4 MYA and 1.6 MYA, respectively. Also, we developed 24 novel microsatellite markers from A. corymbosa and demonstrated high transferability across the genus. We then used these markers to study Antennaria rosea, one of the most morphologically diverse polyploid agamic complexes, with a history of hybridization and introgression from as many as eight diploid to tetraploid sexual Antennaria species. Amount and distribution of genetic diversity within A. rosea populations in the context of their putative sexual diploid/tetraploid progenitors was investigated. Thirty eight populations from eight putative sexual diploid/tetraploid parents of A. rosea and 18 A. rosea populations from their major centers of distribution in the Rocky Mountain regions of the western USA were genotyped for the study. Antennaria rosea populations were assigned into three genetically distinct clusters. Populations within a genetic cluster showed high correlations with regard to geographic distribution and ancestry. Comparatively, A. rosea populations in the northern Rocky Mountain regions had higher levels of heterozygosity than those in the Southern Rocky mountain regions. Based on unconditional maximum likelihood analysis, A. microphylla and A. umbrinella, with wide distributions and high sympatry with A. rosea populations were the major source contributors in the parentage of A. rosea polyploid agamic complex. In conclusion, the highly resolved Antennaria phylogeny and the development of microsatellite markers with high cross species transferability in this dissertation will be valuable for future evolutionary studies in Antennaria.

Comments

Data is provided by the student.

Library Comment

Dissertation or thesis originally submitted to ProQuest

Notes

Open Access

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