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Evolution Of Duplicated Han-Like Genes In Petunia X Hybrida., Beck Powers

Graduate College Dissertations and Theses

Gene duplications generate critical components of genetic variation that can be selected upon to affect phenotypic evolution. The angiosperm GATA transcription factor family has undergone both ancient and recent gene duplications, with the HAN-like clade displaying divergent functions in organ boundary establishment and lateral organ growth. To better determine the ancestral function within core eudicots, and to investigate their potential role in floral diversification, I conducted HAN-like gene expression and partial silencing analyses in the asterid species petunia (Petunia x hybrida). My results indicate duplication of HAN-like genes at the base of Solanaceae followed by expression diversification within the flower. …

Regeneration Responses To Management For Old-Growth Characteristics In Northern Hardwood-Conifer Forests, Aviva Joy Gottesman

Graduate College Dissertations and Theses

Silviculture practices interact with multiple sources of variability to influence regeneration trends in northern hardwood forests. There is uncertainty whether low-intensity selection harvesting techniques will result in desirable tree regeneration. Our research is part of a long-term study that tests the hypothesis that a silvicultural approach called "structural complexity enhancement" (SCE) can promote accelerated development of late-successional forest structure and functions. Our objective is to understand the regeneration dynamics following three uneven-aged forestry treatments modified to increase postharvest structural retention: single-tree selection, group selection, and SCE. In terms of regeneration densities and composition, how do light availability, competition, seedbad, and …

Quantifying Tree Response To Alterations In Pollution Deposition And Climate Change In The Northeastern Us, Alexandra M. Kosiba

Graduate College Dissertations and Theses

Understanding tree physiological responses to climate change is critical for quantifying forest carbon, predicting species' range change, and forecasting growth trajectories. Continued increases in temperature could push trees into conditions to which they are ill adapted -- such as decreased depth of winter snow cover, altered water regimes, and a lengthened effective growing season. A complicating factor is that in the northeastern United States, climate change is occurring on a backdrop of acid deposition and land-use change. In this dissertation, I used three studies to investigate the spatiotemporal nuances of resultant tree and sapling physiology to environmental change.

First, I …

Evolutionary Innovations In Ants To Thermally Stressful Environments, Andrew D. Nguyen

Graduate College Dissertations and Theses

Temperature is a fundamental environmental force shaping species abundance and distributions through its effects on biochemical reaction rates, metabolism, activity, and reproduction. In light of future climate shifts, mainly driven by temperature increases, how will organisms persist in warmer environments? One molecular mechanism that may play an important role in coping with heat stress is the heat shock response (HSR), which protects against molecular damage. To prevent and repair protein damage specifically, Hsps activate and become up-regulated. However, the functional diversity and relevance of heat shock proteins (Hsps) in extending upper thermal limits in taxonomic groups outside marine and model …

Assessing The Efficacy Of Two Species Of Silver Fly, Leucopis Argenticollis And L. Piniperda, As Biological Control Agents Of Hemlock Woolly Adelgid, Adelges Tsugae, Kyle Motley

Graduate College Dissertations and Theses

Adelges tsugae Annand is a non-native invasive insect threatening the survival of eastern hemlock (Tsuga canadensis) and Carolina hemlock (T. caroliniana). A. tsugae is established in over half of the total range of eastern hemlock and the entire range of Carolina hemlock. Its continued spread, establishment and associated hemlock mortality make research into biological control of A. tsugae crucial. Field surveys of predators associated with A. tsugae in the Pacific Northwest identified a strong correlation between A. tsugae abundance with Laricobius nigrinus and two species of silver fly, Leucopis argenticollis and Leucopis piniperda. Flies in the genus Leucopis are known …

Effects Of Plasticity And Hybridization On Life History Traits In Arabidopsis Thaliana Ecotypes, Kattia Paola Palacio Lopez

Graduate College Dissertations and Theses

Understanding the strategies that plant populations implement to increase evolutionary responsiveness to better survive environmental changes induced by climate change is a critical challenge for ecology and evolutionary studies. This dissertation investigates the role of hybridization, local adaptation, and phenotypic plasticity in plant population responses to environmental change. Specifically, I utilized meta-analysis techniques to investigate the prevalence of local adaptation and phenotypic plasticity as the two main mechanisms used to adapt to heterogeneous environments, and experimentally explored the genetic pathway of plasticity in phenology traits such as bolting time in Arabidopsis thaliana under high temperatures. Furthermore, A. thaliana was used …