Doctor of Philosophy, Miami University, 2024, Biology

This dissertation is structured into five chapters. Chapter I: I provide a general introduction to my dissertation, primarily introducing the different influences on intraspecific variation and providing a background on local adaptation. Chapter II: I investigate the effects of environmental conditions and demographic history on populations of desert horned lizards (Phrynosoma platyrhinos). I evaluate the demographic history of P. platyrhinos and identify signatures of selection associated with climate, which may be indicative of local adaptation. I then link signatures of selection to genes and functional genomic elements. Chapter III: I explore the influence of environmental heterogeneity on intraspecific variation of the chisel-toothed kangaroo rat (Dipodomys microps). I discover signals of selection associated with both climate and vegetation. I also find evidence that selective pressures likely vary across the species distribution and develop a permutation test to identify populations that possess more putatively adaptive alleles than expected by chance. I also link signals of selection to genes and biological functions that may be related to previously identified morphological differences between populations. Chapter IV: I perform a meta-analysis to understand general patterns of putative local adaptation in terrestrial chordates. I use previously published datasets and analyze them using a common framework to test theoretical predictions regarding the relationship between environmental and demographic factors and signals of selection. I find that signals of selection follow theoretical predictions, and, importantly, find that constant variation is an important driver of signals of selection. Chapter V: I provide conclusions and future directions from my results.

Committee: Tereza Jezkova (Advisor); David Berg (Committee Member); Donghyung Lee (Committee Member); Richard Moore (Committee Member); Susan Hoffmann (Committee Member) Subjects: Bioinformatics; Biology; Climate Change; Evolution and Development

Doctor of Philosophy, The Ohio State University, 2022, Evolution, Ecology and Organismal Biology

Desert plant communities throughout the arid Southwest are being impacted by a rapidly changing climate. In the Mojave and Sonoran Deserts, severe drought, linked to global climate change, is causing widespread mortality of long-lived species. Biotic interactions, both competitive and facilitative, mediate plant responses to stressful conditions. Consequently, the spatial pattern of plants on the landscape, which determines the intensity of interactions between individuals, is a legacy of past conditions, a moderator of present drought mortality, and a driver of future community change. To better understand how interactions between adjacent individuals affects the rates of growth, survival, and mortality of desert shrubs in a changing climate, in Chapter One I investigated the spatial demography of the numerically dominant species, Ambrosia dumosa (Asteraceae), using a size and neighbor-classified matrix model parameterized with twenty years of data from a permanent one-hectare site in Joshua Tree National Park that spanned periods of historically average climate and extreme drought. I classified 9,215 Ambrosia individuals into six size classes and two neighbor states. Differences in the demography of isolated and neighbored population subsets of this species shifted with drought, illustrating how spatial pattern mediates the impact of climate change. High interannual and intra-annual variability in rainfall challenges desert shrub seedlings with a tradeoff between drought tolerance and competitive ability. I hypothesized that Ambrosia seedlings can acclimate to wetter or drier conditions by modifying their proportion of roots and leaves, based on early-life moisture cues. In Chapter Two I performed a greenhouse experiment to investigate how root/shoot allocation of Ambrosia was affected by variation in the timing of water availability. Seedlings received the same total quantity of water, differing only in the timing of water delivery. Seedlings lacking wa (open full item for complete abstract)

Committee: Maria Miriti (Advisor); Stephen Hovick (Committee Member); G. Matthew Davies (Committee Member); Elizabeth Marschall (Committee Member) Subjects: Biostatistics; Conservation; Demography; Ecology