Doctor of Philosophy, The Ohio State University, 2022, Environmental Science

Tropical savannas support globally important biological diversity and provide a variety of cultural and economic ecosystem-services to humans. As mosaic landscapes, they are characterized by the coexistence of woody and grassy habitats which are strongly regulated by abiotic gradients (e.g., soils, climate) and local disturbance regimes (e.g., fire, flooding and grazing). Consequentially, savannas are inherently dynamic over a variety of scales and provide an array of temporal and spatial ecological niches for wildlife. However, tropical savannas and their ecological functions have been widely degraded by intensifying human land-use and are threatened by impending climate change. Unfortunately, our scientific understanding of savanna ecology is currently limited, impeding development of appropriate conservation approaches. This is especially true of Neotropical systems. This dissertation provides new research, carried out within the Beni, a seasonally flooded Neotropical savanna in Bolivia, that aims to address critical knowledge gaps in savanna ecology. This research will contribute to developing sustainable land management and restoration initiatives to secure and protect savanna ecosystems for people and wildlife. The overarching aim was to understand how ecological (flooding) and agricultural (managed fire and cattle grazing) disturbance influences habitats and wildlife in Beni. To achieve this, three specific objectives were identified: 1) understand how restoration, through cessation of long-term cattle grazing impacts (i) regeneration, (ii) understory structure and composition, and (iii) abundance and diversity of large mammals and nocturnal birds, within the regions' naturally patchy gallery forests; 2) examine how compounded disturbance from flooding and fire shapes the distribution of woody plants and habitats across a savanna-grassland mosaic; and 3) determine functional responses of avian biodiversity to livestock removal across a savanna-grassland ec (open full item for complete abstract)

Committee: G. Matt Davies (Advisor); Christopher Tonra (Advisor); Stephen Matthews (Committee Member); Kaiguang Zhao (Committee Member) Subjects: Conservation; Ecology; Environmental Science; Range Management; Wildlife Conservation

Master of Sciences, Case Western Reserve University, 2018, Biology

The Sparassodonta were a group of carnivorous metatherians that were one of the dominant groups of terrestrial predators in South America during the continent's Cenozoic isolation. However, the fossil record of Sparassodonta has been largely biased towards sites in Argentina, particularly from the Southern Cone. Here, I describe three new species of sparassodonts, each represented by a single specimen, from Bolivia and Chile. The first species, from the late middle Miocene of Quebrada Honda, Bolivia, represents one of the smallest sparassodonts known. The second species, from the late Eocene of central Chile, is an early borhyaenoid and indicates that the diversity and disparity of borhyaenoids prior to the Oligocene was higher than previously appreciated. The third species, from the early Oligocene of central Chile, is the one of the first early Oligocene sparassodonts known from more than a single tooth and may represent an early thylacosmilid.

Committee: Hillel Chiel (Committee Chair); Darin Croft (Advisor); Michael Benard (Committee Member); Scott Simpson (Committee Member) Subjects: Animals; Biology; Evolution and Development; Organismal Biology; Paleoecology; Paleontology; Zoology

Doctor of Philosophy, The Ohio State University, 2016, Evolution, Ecology and Organismal Biology

The Neotropics is the most species-rich region in the world. The current diversity and distribution of lineages present in this region is in part the result of complex ecological and evolutionary trends determined by environmental variables that have operated at diverse spatial and temporal scales. In addition, demographic processes have also influenced the structure of present-day phylogeographic patterns. Several studies have used Neotropical pitvipers as model organisms to explore historical diversification patterns and ecological processes that produce diversity in this region. However, few of those studies have explored patterns of diversification for groups of pitvipers likely influenced by one of the most salient features of the South American continent: The Andes. Here, I use a combination of molecular, morphological, and geographical data to explore diversification patterns and the evolutionary mechanisms implicated in the divergence of two distinct members of the genus Bothrops. First, I examine cryptic diversity present in the widespread and medically important snakes of the B. asper species complex (Chapter 2). Using a genomic and morphological dataset collected across the distribution of the group, I identified extensive phylogeographic structure, suggesting the influence of geographic barriers and/or differences in ecological niches in the recent diversification in the group. A deep divergence between a Central and South American clade is evident, but more recently diverged groups in South America show complicated patterns suggestive of recent divergence and/or gene flow among lineages. Next, I use this information to perform model-based analyses to investigate the demographic processes involved in the recent origin of two Ecuadorian montane lineages of these pitvipers (Chapter 3). This approach allowed me to resolve some of the discrepancies of evolutionary relationships found in Chapter 2. I found evidence for the isolation of one of the montane line (open full item for complete abstract)

Committee: H. Lisle Gibbs (Advisor); Paul A. Fuerst (Committee Member); Thomas Hetherington (Committee Member); John Freudenstein (Committee Member) Subjects: Ecology; Evolution and Development; Zoology

Doctor of Philosophy, Miami University, 2010, Botany

Pleopeltis polypodioides is a widespread Neotropical epiphytic fern species currently composed of six varieties: acicularis (Weath.) E.G. Andrews & Windham, burchellii (Baker) A.R. Sm., knoblochianum Mickel, michauxiana (Weath.) E.G. Andrews & Windham, minus (Fee) Weath., and polypodioides (L.) E.G. Andrews & Windham, plus one subspecies: ecklonii (Kunze) Roux. The species was initially included within Polypodium but recent authors, utilizing molecular data, have placed it within Pleopeltis. The taxonomic boundaries of Pleopeltis remain controversial despite recent investigations into its circumscription. The objectives of this dissertation were to explore the taxonomic affinity of the Pl. polypodioides complex within Pleopeltis, and its interspecific relationships using molecular phylogenies and morphological analyses. In addition, generic affinities and geographic distributions of Pl. polypodioides, as well as infraspecific relationships were examined. Originally, differentiation among the members of the complex was based primarily on leaf venation pattern and the presence or absence of laminar (leaf) scales on the adaxial (upper) surface. This species is characterized by an epiphytic habit, deeply pinnatifid fronds, round sori that are embedded into the laminar tissue creating an embossed appearance on the upper service of the leaf, a covering of persistent scales on the lower (abaxial) surface, free and/or anastomosing leaf venation, and sori supplied by a single vein. Glandular structures are present on the acroscopic side of the pinnae-segments, and rhizome scales have a black center at the point of attachment and generally with a black sclerotic medial band. In addition to an epiphytic habit, this species exhibits a particularly fascinating aspect of desiccation tolerance. When conditions become dry, the fronds completely curl inward and remain dormant until water is more readily available. Once moisture increases, the fronds rapidly unfurl by channeling wate (open full item for complete abstract)

Committee: James Hickey PhD (Committee Co-Chair); Linda E. Watson PhD (Committee Co-Chair); Michael A. Vincent PhD (Committee Member); Richard C. Moore PhD (Committee Member); John Bailer PhD (Committee Member) Subjects: Biology; Botany; Genetics