Thesis (Ph. D.)--University of California, Los Angeles, 2003. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--University of Oulu, 1988. / List of original papers of the author. Includes bibliographical references.

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xi, 98 leaves ; 28 cm Notes Typescript Thesis (Ph. D.)--University of Oregon, 1983 Includes vita and abstract Bibliography: leaves 92-98 Another copy on microfilm is located in Archives

This dissertation represents a study on Ceratocystis spp. with hat-shaped ascospores. Previously only six species of Ceratocystis with this spore form were known. These include C. fimbriata, C. pirilliformis, C. albofundus, C. moniliformis, C. moniliformopsis and C. acericola. In this study, we have discovered and tentatively described three new species with hat-shaped ascospores. One of these group with the larger C. fimbriata clade, while the other two reside within the larger C. coerulescens clade. Chapter one provides a concise summary of the literature pertaining to the genus Ceratocystis. The intention of the chapter is to introduce readers to this important genus of plant pathogens and to provide a background regarding their taxonomy, ecology, biochemistry and variation in species. Emphasis is placed on the distinction of Ceratocystis from Ophiostoma, as ell as on those Ceratocystis spp. with hat-shaped ascospores that negatively impact upon plantation forestry species. This chapter shows how Ceratocystis spp. associated with hardwood species in commercial forestry plantations have increased in number and it provides the background for research presented in the following five chapters. In the second chapter of this dissertation, a new species of Ceratocystis was discovered amongst isolates from the Himalayan mountain range of Bhutan. This fungus, in association with the bark beetle Ips schmutzenhoferi, is responsible for large-scale deaths of Himalayan spruce trees in Bhutan. The fungus is morphologically very similar to C. moniliformis and C. moniliformopsis, but differences in culture morphology, survival at different incubation temperatures and DNA sequence data based on three different gene regions supported the fact that this is a unique species. The fungus has thus been tentatively described as Ceratocystis bhutanensis prov. nom. In chapter 3, I consider isolates of a Ceratocystis sp. recently discovered associated with dying clove trees in Northern Sulawesi, Indonesia. The fungus was found at a very high level of incidence, but was at first identified as C. fimbriata, based on morphological characteristics. Differences were observed in cultures of this fungus when they were compared with C. fimbriata especially in terms of colony colour and growth at different temperatures. Morphological differences were also observed when the clove fungus was compared with C. fimbriata isolates. When three different DNA gene regions were sequenced and compared, it was clear that this fungus represents a new species. The fungus is, therefore, tentatively described as Ceratocystis polychrome prov. nom. in this dissertation. Ceratocystis polychrome prov. nom. Isolates obtained from cloves in Sulawesi displayed three distinctly different culture morphologies. In Chapter 4 of this dissertation we used DNA sequence data and microsatellite markers to consider whether these differences could be observed at the molecular level. Comparisons of sequence data for the ITS region gave no distinction between any of the morphological groups. A total of 50 isolates were studies using microsatellites markers developed for C. fimbriata. No distinction could be obtained between isolates representing the three different culture morphological groups. The 50 isolates were subsequently treated as one population in further analyses. With the aid of the microsatellite markers, it was shown that this population probably originated from Sulawesi and that it benefits form sexual outcrossing. In chapter five of this dissertation, a study was undertaken to consider the taxonomic status of C. moniliformis. Consideratble variation has been noted in different descriptions of this species. It also has a very wide host and geographic distribution raising speculation that C. moniliformis represents a species complex rather than a single taxon. Based on morphological and DNA sequence data from three gene regions, isolated from Sumatra were described as a new species, which we have tentatively named C. tribiliformis prov. nom. The other C. moniliformis isolates were all the same, despite the fact that they originated from a wide range of hosts and areas. The fungus correctly bearing the name C. moniliformis, C. moniliformis sensu stricto, therefore does not seem to tepresent a species complex. Species such as the closely related C. tribiliformis prov. nom., C bhutanensis prov. nom., C. omanensis prov. nom. and C. moniliformopsis all belong to the larger C. moniliformis sensu lato group, and all have hat-shaped ascospores, conical spines on the ascomatal bases, disc-shaped bases to the ascomatal necks and are phylogenetically closely related to C. moniliformis. Studies presented in this dissertation provide considerable new knowledge regarding various Ceratocystis spp. with hat-shaped ascospores. Three new species are described and I have also been able to show that C. moniliformis sensu stricto is monophyletic. Two of the species (C. tribiliformis prov. nom. and C. bhutanensis nom. prov.) group within the larger C. coerulescens clade while C. polychrome prov. nom. groups within the larger C. fimbriata clade. Studies in this dissertation have also improved our knowledge of the identity of several species previously incorrectly identified as either C. moniliformis or C. fimbriata. What has clearly emerged from this dissertation is the need for a monograph of Ceratocystis to include all new species and to thoroughly consider the population biology and ecology of all species. / Dissertation (MSc)--University of Pretoria, 2008. / Microbiology and Plant Pathology / MSc / Unrestricted

MSc (Botany) / Department of Botany / The overall aim of this study was to determine the population biology of Sclerocarya birrea (A Rich) Hochst., subspecies caffra (Sond) at Nylsvley Nature Reserve, Limpopo, South Africa. Sclerocarya birrea is a keystone plant species which is rated as one of the most highly valued indigenous trees because of its multiple uses. It is identified as a key species to support the livelihood of rural communities and it is central to various commercial activities. Sclerocarya birrea is also widely used by game in protected areas and by humans in communal areas for its fruit, wood and medicinal properties. Understanding the population biology for this key stone species is important as there are many environmental factors that are affecting its population structure. The study found that the population of S. birrea at Nylsvley Nature Reserve is fairly healthy and is mainly comprised of seedling and adult trees. Evidence of predators feeding on the seeds of Sclerocarya birrea was also recorded in this study. Additionally, disturbance, such as fire and cutting do not have negative impact on S.barrea

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Predator populations can have significant impacts on prey recruitment success and prey population dynamics through consumption. Young, inexperienced prey are often most vulnerable to predation due to their small size and limited evasion capabilities. to reduce the risk of predation, new recruits and young juveniles typically settle in structured nursery habitats, such as seagrass beds, which promote higher survival by acting as refuges from predators. Thus, successful recruitment to the adult portion of the population is often dependent on the availability of suitable nursery habitat. In this thesis, I used field tethering experiments and gut content analyses to assess the role of habitat, body size, finfish predation, and cannibalism on the survival of one of the most ecologically and economically important species in Chesapeake Bay: the blue crab Callinectes sapidus. In field tethering experiments, survival probability of juvenile blue crabs in York River nursery habitats (i.e. seagrass beds, sand flats) increased significantly and additively with crab size and SAV cover. Images of predation events during tethering experiments revealed cannibalism by adult blue crabs to be a major source of juvenile mortality. Gut content analyses from three field studies identified seven predators of juvenile blue crabs in lower Chesapeake Bay nursery habitats: adult blue crabs, striped bass Morone saxatilis, red drum Sciaenops ocellatus, silver perch Bairdiella chrysoura, weakfish Cynoscion regalis, Atlantic croaker Micropogonias undulatus, and oyster toadfish Opsanus tau. Using frequency of consumption and diet proportion metrics, I determined striped bass, red drum, and silver perch to be the most impactful finfish predators on juvenile mortality, in addition to cannibalism. Atlantic croaker and oyster toadfish play minor roles in juvenile mortality in Chesapeake Bay nursery habitats. The probability of juvenile crabs being present in a predator’s gut was also significantly higher in seagrass beds than in unvegetated sand flats. Food web dynamics are an important aspect of ecosystem-based fisheries management. Understanding the ecological interactions between populations, and their environment, can provide insight into natural population fluctuations of valuable fishery species such as the blue crab. This thesis demonstrated the positive effects of body size and SAV cover on juvenile crab survival, indicating the importance of seagrass nursery habitat for blue crab population dynamics in Chesapeake Bay. However, despite the predator refuge offered by SAV, high densities of predators and prey in seagrass beds resulted in greater consumption of juveniles in those habitats. Key predators of juvenile blue crabs were also identified and their relative impacts were estimated. The predator-prey relationships revealed in this thesis were integrated into a revised food web for blue crabs in Chesapeake Bay, in the hopes of informing future ecosystem-based management efforts.

Migratory species are expected to demonstrate habitat selection that occurs at multiple spatial and temporal scales. Western monarch butterflies migrate seasonally to overwinter in groves at geographically predictable locations along the California coast. To date, overwintering habitat selection by western monarch butterflies has been studied assuming that habitat selection occurs where overwintering aggregations form, meaning at the spatial scale where monarchs form dense overwintering aggregations within overwintering groves. We argue that since western monarch butterflies are migratory, studies of habitat selection could have commingled selection at different scales into a single spatial scale. This likely leads to ignoring some levels of habitat selection, confounding the scale of habitat selection itself, and potentially misidentifying the habitat attributes under selection. Therefore, we explore monarch overwintering habitat selection to determine whether an explicit spatial framework is necessary.We studied nine groves on the coast of California and at each grove we collected temperature, humidity, and light data from grove edges, grove interiors, and aggregation locations over several weeks of the overwintering season. We tested the hypothesis that monarchs aggregate in locations within groves that have consistent attributes across groves. We find that locations on the outer edges of groves differed significantly in particular attributes of daily temperature and light from the interior of groves. Yet we find neither evidence supporting the hypothesis that the aggregation locations have a unique microclimate that differs significantly from other locations inside the grove nor that aggregation locations are uniform in their microclimatic attributes across overwintering groves. Rather, we find that the microclimatic attributes at the aggregation locations vary spatially with latitude. Thus, the overwintering climatic attributes that appear to be under selection varied spatially based on locations within groves and based on latitude of each particular grove. We conclude it will be necessary to consider spatial effects when studying western monarch butterfly overwintering habitat selection and that interpretations of habitat selection to date have commingled habitat selection at multiple spatial scales.

During January 1983 - July 1985 the population dynamics, movements, and habitat use of pronghorns (Antilocapra americana) were studied on the 1040 km² Piñon Canyon Maneuver Site, in southeastern Colorado, prior to initiation of military training. Forty-seven adults and 32 fawns were radio marked; 247 adults were color collared or ear tagged only. Using aerial strip and quadrat surveys, I estimated a summer population for 1983, 1984, and 1985 of 694, 690, and 657 respectively. Adult female pregnancy rate was approximately 98%, mean litter size for females > 1.5 years was 1.9, and fetal and fawn sex ratios were not different from 1:1. Fawn mortality was 89% in 1983 and 80% in 1984. Adult mortality was 20% in 1983 and 28% in 1984. Annual rate of increase (λ) over the 2 year study was .806. Home range size of pronghorns was extremely variable within and between sexes and among seasons. Winter ranges were 2-fold and 5-fold larger than summer range for females and males, respectively. Sixty-five percent of all weekly movements were < 3 km. Females preferred open grassland in all seasons, and cholla grassland in winter. Yucca grassland was preferred in spring and fall, and cholla/open grass edges were highly preferred in all seasons. Males preferred open grassland in all seasons but winter, and preferred cholla grassland in all seasons but spring, cholla/open grass edges were also preferred in all seasons. Fawns used open grassland and cholla/open grass edges more than expected, while using woodland and shrub habitats less than expected. / M.S.