Digital Commons Network^™

Drought Tolerance In Native And Invasive Populations Of The Centaurea Jacea Hybrid Complex, Zoe Portlas

Graduate College Dissertations and Theses

Introduced plants face many ecological and evolutionary challenges when establishing in a new range, such as strong abiotic stressors and potentially novel selective environments. One such abiotic stress is water availability, which is a strong selective force shaping physiological and phenological traits that enable plants to tolerate or avoid drought stress. Despite the challenges of establishing in a new range, thousands of species have become invasive in recent centuries. Two hypotheses that may explain how a species is able to withstand stress in its introduced range are preadaptation, which posits that species are adapted to similar environments in their native …

From Gondwana To Gaarlandia: Molecular Phylogenetics And Historical Biogeography Of Spiders, Lisa Chamberland

Graduate College Dissertations and Theses

The distributions of Earth’s flora and fauna are shaped by a myriad of biotic and abiotic factors including dispersal capacity, and the geologic histories of landscapes. The relative importance of long-distance (overland or overwater) dispersal and vicariance, or the subsequent separations of populations via physical barriers (e.g. mountains, rivers, oceans) in shaping the disjunct distribution of taxa, are the two main biogeographic hypotheses used to explain disjunct distributions. This research explored the evolutionary histories of spiders to test how long-distance dispersal and vicariance have generated species diversity and distributions are shaped on local and global scales. In the first part …

A Generic Classification Of The Thelypteridaceae, Susan E. Fawcett

Graduate College Dissertations and Theses

The Thelypteridaceae is among the largest fern families, with over 1000 species, and comprises about 10% of all fern diversity. The family is cosmopolitan and most diverse near the equator, although species range as far north as Greenland and Alaska, and as far south as southern New Zealand. The generic classification of the Thelypteridaceae has been the subject of much controversy among authors. Proposed taxonomic systems have varied from recognizing more than 1000 species in the family within a single genus, Thelypteris, to systems favoring upwards of 30 genera. Insights on intrafamilial relationships have been gained from recent phylogenetic studies, …

Evolutionary History Of The Angiosperm Npf1 Gene Subfamily: Duplications, Retention And Functional Implications For Root Symbioses And Development, Giovanna Sassi

Graduate College Dissertations and Theses

ABSTRACT

The success of land plants can be attributed to the evolution of beneficial associations between plant roots and soil microbes. Root-microbe mutualisms extend the range of plant nutrient acquisition delivered through the hyphal network of mycorrhiza, an ancient and widespread plant symbiosis, or by the more recent adaptive innovation of nitrogen-fixing nodule symbioses. A plant’s genetic toolkit governs its selection of beneficial symbionts and the developmental extent of these intimate interactions. However, the evolutionary origins and function for only a few symbiotic signaling components have been explored. The central aim of this dissertation is to resolve the evolutionary events …

Devonian Origin And Cenozoic Radiation In The Clubmosses (Lycopodiaceae), Weston Testo

Graduate College Dissertations and Theses

Together with the heterosporous lycophytes, the clubmoss family (Lycopodiaceae) is the sister lineage to all other vascular land plants. Given the family’s important position in the land-plant phylogeny, studying the evolutionary history of this group is an important step towards a better understanding of plant evolution. Despite this, little is known about the Lycopodiaceae, and a well-sampled, robust phylogeny of the group is lacking. The goal of this dissertation is to resolve the relationships among evolutionary lineages in the Lycopodiaceae and provide insight into the timing and drivers of diversification in the family.

First, to place the evolution of the …

Temporal Feature Selection With Symbolic Regression, Christopher Winter Fusting

Graduate College Dissertations and Theses

Building and discovering useful features when constructing machine learning models is the central task for the machine learning practitioner. Good features are useful not only in increasing the predictive power of a model but also in illuminating the underlying drivers of a target variable. In this research we propose a novel feature learning technique in which Symbolic regression is endowed with a ``Range Terminal'' that allows it to explore functions of the aggregate of variables over time. We test the Range Terminal on a synthetic data set and a real world data in which we predict seasonal greenness using satellite …

Evolution Of Vernalization And Photoperiod-Regulated Genetic Networks In The Grass Subfamily Pooideae, Meghan Mckeown

Graduate College Dissertations and Theses

Flowering time is a carefully regulated trait that integrates cues from temperature and photoperiod to coordinate flowering at favorable times of the year. This dissertation aims to understand the evolution of genetic architecture that facilitated the transition of Pooideae, a subfamily of grass, from the tropics to the temperate northern hemisphere approximately 50 million years ago. Two traits hypothesized to have facilitated this evolutionary shift are the use of long-term low-temperature (vernalization) to ready plants for flowering, and long-day photoperiods to induce flowering. In chapter one I review literature on the regulation of grass flowering by vernalization and photoperiod, and …

Teaching Evolution With Palentological Data: A Web Resource, Corey C. Coutu

Graduate College Dissertations and Theses

Over the past thirty years, the presence of naïve notions, or alternate conceptions in a student population, have been consistently identified as playing a key role in the inability for students to understanding evolutionary theory (Brumby, 1979; Greene, 1990; Settlage, 1994; Ferrari and Chi, 1998). Ferrari and Chi (1998) document that most naïve notions associated with evolution education can be linked to mistaken ontological categorizations, where students associated evolutionary concepts with event process (where organisms determine implicitly or explicitly their destiny) instead of equilibration processes (ongoing, nondistinct actions) to which they belong. Research in the remediation of naïve knowledge (Ferrari …