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The Genus Isoetes L., Evolution, Diversification and Population Structure in a Free-Sporing Heterosporous Lycophyte- [electronic resource]
The Genus Isoetes L., Evolution, Diversification and Population Structure in a Free-Sporin...
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The Genus Isoetes L., Evolution, Diversification and Population Structure in a Free-Sporing Heterosporous Lycophyte- [electronic resource]
자료유형  
 학위논문파일 국외
최종처리일시  
20240214095919
ISBN  
9798380368643
DDC  
580
저자명  
Freund, Forrest.
서명/저자  
The Genus Isoetes L., Evolution, Diversification and Population Structure in a Free-Sporing Heterosporous Lycophyte - [electronic resource]
발행사항  
[S.l.]: : University of California, Berkeley., 2022
발행사항  
Ann Arbor : : ProQuest Dissertations & Theses,, 2022
형태사항  
1 online resource(172 p.)
주기사항  
Source: Dissertations Abstracts International, Volume: 85-03, Section: B.
주기사항  
Advisor: Rothfels, Carl.
학위논문주기  
Thesis (Ph.D.)--University of California, Berkeley, 2022.
사용제한주기  
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초록/해제  
요약Among land plants, one of the most cryptic lineages is the genus Isoetes L., both in terms of public awareness and appearance. Taxonomically, Isoetes are members of the vascular plant Division Lycopodiophyta, the sister lineage to the more well-known and lineage rich Euphyllophyta, which includes both the Monilophytes (ferns) and Spermatophytes (seed plants). Lycophytes are comprised of three extant lineages, the homosporous order Lycopodiales, which have the greatest extant generic diversity within the lineage, and the heterosporous Selaginellales and Isoetales, both of which are contemporarily monogeneric. Lycophytes are united by a few key features, including the microphyll, a leaf type unique to the lineage, and adaxial placement of the sporangia on the sporophylls. Like the Monilophytes, Lycophytes are free-sporing plants. As such, they have a pronounced alternation of generations, with a large, dominant diploid sporophyte producing haploid spores via meiosis, which go on to germinate into haploid gametophytes. These gametophytes produce either or both haploid eggs and sperm, which unite within the gametophyte's archegonia to produce a new diploid sporophyte embryo.The Isoetalean lycopods, both extinct and extant, are particularly unique among their relatives due to both a suite of unusual characters. One of the first and most obvious of them is their growth form. Unlike their fellow lycophytes, which have unipolar growth, meaning they grow and elongate via a terminal apical meristem on the shoot system, and produce adventitious roots from this stem axis, Isoetaleans have bipolar growth like most Spermatophytes. And, like the non-monocot Spermatophytes, the Isoetaleans undergo secondary growth, adding both cortical tissue and secondary vascular tissue via a meristematic region known as the prismatic layer. In the extinct Isoetalians, these two traits allowed them to become arborescent, with some of the largest members, such as Lepidodendron Sternberg growing to over ten meters tall.Today, Isoetes is the only remaining member of Isoetales Prantl. The genus appears to have arisen in the Triassic and can be found throughout the non-polar regions of the world in seasonally to permanently hydric to aquatic habitats. Morphologically, Isoetes have a highly conserved base bodyplan; almost all of them are small, perennial, semi-herbaceous geophytes whose body is comprised of a highly reduced 1-3 lobed, corm-like trunk, an apical rosette of long, simple, linear leaves, and numerous roots that emerge from their basal furrow. Species are identified through a combination of habitat, spore color, ornamentation and size, leaf morphology, corm lobe numbers, and size of the plants themselves. Because their morphology is so conserved, species identification can be difficult in areas where multiple taxa overlap, especially when the taxa in question are close relatives, as the plants are known to readily hybridize with one another, or form allopolyploids.Modern Isoetes can be broken up into five distinct sub-clades, which predominantly correspond to their geographic range. There is the Gondwanan clade, which is found in Southern Africa, South America, India and Australia. The Laurasian clade, which occur in the Mediterranean region of Europe and North Africa, North America, and India. The Italian clade, which occurs in and around the Italian peninsula. The Austro-Asian clade, found in Eastern and Southern Asia, India and Australia. And the American clade, which is found in North and South America, as well as a few circumboreal species, and the only known species in Oceania. Because Isoetes is so morphologically conserved, prior to molecular phylogenetics it was assumed that spore morphology or habitat types defined the taxonomic groups, which we now know not to be the case. In fact, these traits are quite labile, particularly when polyploids are involved. In this dissertation, I explore the evolution of one of the traits in extant Isoetes through ancestral state reconstruction, as well as conduct multi-locus population genetic and phylogenetic analyses to determine if the species composition in one of the sub-clades found on the West Coast of North America. In my first chapter, I take published morphological data on the corms of modern Isoetes in conjunction with one of the most recently published genus-wide phylogenies to infer how the number of corm lobes have evolved within the genus. Contemporary Isoetes are either bi-lobate or tri-lobate, a trait that does not seem to be restricted to a single clade, but has arisen in multiple different lineages. To examine the evolution of this convergent morphology, I conducted an extensive literature review of published type descriptions in conjunction with monographic sources to code the trait of corm lobation in as many species of Isoetes as possible, with special emphasis placed on finding descriptions of species included in said phylogeny. Using the program RevBayes using Reversable Jump Markov Chain Monte Cristo (RJMCMC) and the 15,000 tree posterior distribution from Larsen and Rydin 2016, we inferred which of the five evolutionary models of change in corm lobation (bi-to-tri, tri-to-bi, 1-rate reversable, 2-rate reversable, and invariant). From the ancestral state reconstruction and model analysis, the most well supported model of character evolution of corm lobation in extant Isoetes an irriversable change from tri to bilobate, though the reversable models had significant non-zero probabilities as well.In my second chapter, I generated novel molecular data for the Pacific Laruasian clade (PLC), a small, disjunct sub-clade found on the west coast of North America in Southern British Columbia, Washington, Idaho, Oregon, California and northern Baja, for the purpose of generating a clade wide phylogeny and population genetics analysis. The nearest relatives of this subclade are found in Europe and India, with the estimated divergence time between the two dated to around 34 MYA during the transition from the Eocene to Oligocene. 8-12 individuals were collected from 22 populations located across much of the range (specifically California and Oregon) of and identified to the following species based on the published keys: Isoetes nuttallii and Isoetes orcuttii. Full genomic DNA was extracted from a total of 136 samples from the PLC, along with two outgroup species (I. howellii and I. bolanderi) from the distantly related American clade, were sequenced using the GoFlag probe set at the University of Florida. Sequences fragments were assembled with a newly developed version of HybPiper, a next-generation sequence assembly pipeline that generate sequence assemblies and call variants from short-read DNA data assembled to the 450 reference sequences used to develop the GoFlag probes. Of these 450 reference loci, we recovered 215 single-copy genes, which were used to infer the phylogenetic relationships among the PLC using the multi-species coalescent. In addition, we used the pop-gen program ANGST to generate admixture plots, F-statistics, and Mantel test. These two types of analysis, when combined, show that the existing taxonomy of the PLC does not reflect the phylogenetic structure of the PLC.In my third chapter, I used the results of my phylogenetics and population genetics chapter as a framework to assess the existing taxonomy of the PLC, and whether it should be reivised in light of my results. In order to do so, I measured the available morphological features of the plants commonly used for species delimitation in Isoetes, as well as made qualitative assessments of their spore morphology, leaf characters and pressence of characters like phyllopodia or scales. From the quantitative data, I performed MANOVA/ANOVA and PCA analysis of their leaf and spore sizes to determine if there were morphological features within each of the clades inferred in Ch. 2 that could be used to distinguish them. Similarly, qualitative characters were compiled and compared to find morphology that supported the structure of the phylogeny. As a result, I highlight the need for taxonomic revision in the PLC, as well as identifying putative new species.
일반주제명  
Botany.
일반주제명  
Morphology.
일반주제명  
Plant sciences.
일반주제명  
Genetics.
키워드  
Coalescence
키워드  
Lycophytes
키워드  
Systematics
키워드  
Taxonomy
키워드  
Isoetes
기타저자  
University of California, Berkeley Integrative Biology
기본자료저록  
Dissertations Abstracts International. 85-03B.
기본자료저록  
Dissertation Abstract International
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