A research report submitted to the Faculty of Science, University of the Witwatersrand, in partial fulfilment of the requirements for the Degree of Masters of Environmental Sciences by Coursework and Research Report. Johannesburg 24 March 2016 / In southern Africa, the baobab (Adansonia digitata L.) is an economically important trees because it contributes significantly to the livelihoods of local people, particularly in northern Limpopo in South Africa (the southern-most edge of the baobab distribution). All parts of the baobab are useful and considered important for subsistence and commercial uses. Understanding factors that affect fruit and seed production is important to better characterize the long-term success of tree populations. Some adult baobab trees have high fruit production (50 −299 fruits per tree, per year) and are subsequently called ‘producers’ or ‘female’ trees, while there are other trees that produce fewer fruits (< 5 fruits per tree, per year) that are called ‘poor-producers’ or ‘male’ trees. For this study, baobab fruit dimensions (mass, length, volume and ratio) were, measured and compared between artificially- and naturally-pollinated producer and poor-producer trees. Fruit dimensions were also correlated to the number of seeds per fruit. Using 2D geometric morphometric analysis, baobab fruit shapes were analyzed and compared to determine if fruit shape differs between fruits formed on producer and poor-producer baobab trees. I found no significant difference in fruit shape between producer and poor-producer baobab trees. Although, artificially-pollinated trees produced bigger and more uniform shaped fruits and contained more seeds in comparison to the smaller unevenly shaped fruits produced by naturally-pollinated trees. Furthermore, I compared fruit and seed production between naturally-pollinated producer/poor-producer and between artificially-pollinated producer/poor-producer trees that occur on different land use types (i.e. nature reserves, rocky outcrops, plains, fields (land use for agricultural purposes) and villages) in Northern Venda, South Africa. There was a significant difference in fruit and seed production between naturally and artificially-pollinated producer and poor producer trees that occur on different land use types. On average, producer trees yielded more seeds than poor-producer trees. The highest fruit and seed production was recorded in fields and villages. Seed mass variation also differed significantly between producer and poor-producer trees and between the different land use types. A very weak negative relationship between baobab seed number and mass was found in both producer and poor-producer baobab trees. Baobab seed viability was estimated using a 0.1% tetrazolium solution, 100% viability was found in all tested seeds from both producer and poor-producer baobab trees. Result of this study may aid with the identification of land use types where baobabs have the lowest seed production and therefore require additional conservation effort to ensure that fruits are harvested sustainably. The estimation of seed production may improve the ability to estimate the total seed oil that is available in each land use type. / M T 2016

No description available.

Steelhead and rainbow trout are common names for marine-migratory (anadromous) and freshwater-resident forms of Oncorhynchus mykiss, a partially migratory salmonid fish. Anadromous and resident forms are sympatric and can produce offspring with a life history different from their own (i.e., steelhead parents can produce rainbow trout offspring and vice versa). The expression of these alternative life histories is a plastic response to individual patterns of energy acquisition, assimilation, and allocation during juvenile life stages. Individual performance during early stream life is of particular interest because of potential carry-over effects on subsequent growth and developmental trajectories. In a series of experiments in laboratory streams, I determined the influence of individual variation in energy metabolism on behavior, growth, and life-history expression in O. mykiss. Individual variation in energy metabolism was a strong predictor of feeding territory acquisition by juvenile fish during the transition from dependence on maternal provisioning of egg yolk reserves to independent feeding. Feeding territory acquisition was positively associated with standard metabolic rate (SMR) under conditions of an abundant and predictable food supply. When the density of intraspecific competitors was manipulated, the association between SMR and territory acquisition was strongest at intermediate stocking densities, moderate at the highest stocking densities, and weakest at the lowest stocking densities. However, reducing the spatial predictability of food resources within streams reversed the influence of SMR on competitive outcomes. These experiments determined that variation in ecological conditions during early life stages imposes different selection regimes on juvenile O. mykiss and results in physiological divergence among cohorts. Subsequent rearing experiments determined that behavioral dominance influences rates of anadromy and freshwater maturation, most likely through the association between SMR and territory acquisition. In addition to the effects of behavioral dominance, I observed a significant influence of sex, rearing temperature, and individual growth trajectories on the expression of anadromy and freshwater maturation. Partially migratory populations of O. mykiss maintain an exceptionally diverse portfolio of life-history strategies. Results from this work lend insight into a suite of behavioral and physiological processes influencing individual life histories. / Graduation date: 2013

In the round worm C. elegans, it has recently been shown that autophagy, a highly conserved lysosomal degradation pathway that is present in all eukaryotic cells, is required for maintaining healthspan and for increasing the adult lifespan of worms fed under dietary restriction conditions or with reduced IGF signaling. It is currently unknown how extracellular signals regulate autophagy activity within different tissues during these processes and whether autophagy functions cell-autonomously or nonautonomously. We have data that for the first time shows autophagy activity in the neurons and intestinal cells plays a major role in regulating adult lifespan and the longevity conferred by altered IGF signaling and dietary restriction, suggesting autophagy can control these phenotypes cell non-autonomously. We hypothesize that autophagy in the neurons and intestinal cells is an essential cellular process regulated by different signaling pathways to control wild type adult lifespan, IGF mediated longevity and dietary restriction induced longevity. Excitingly we also have found that in animals with reduced IGF signaling autophagy can control longevity in only a small subset of neurons alone. Autophagy in either specific individual chemosensory neurons or a small group of them is completely sufficient to control IGF mediated longevity. This work provides novel insight to the function and regulation of autophagy which will help shed light on understanding this essential process in higher organisms, including mammals. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection

The cues used by marine turtles to locate foraging areas in the open ocean are largely unknown though some species (especially the green turtle [Chelonia mydas], the loggerhead [Caretta caretta], and the leatherback [Dermochelys coriacea]) somehow locate areas of high productivity. Loggerheads can detect airborne odors, but a capacity to orient has not yet been investigated. In this comparative study, tethered loggerheads and leatherbacks were exposed to dimethyl sulfide (DMS) or food odors in a laminar flow of air. Turtles did not orient into the air current. Free-swimming loggerheads and green turtles were also exposed to air- or waterborne food (squid) odor plus a neutral visual stimulus. Both species showed increases in swimming activity and biting behavior to both stimuli. These results suggest that airborne odors are likely not used to locate distant areas, but that they are used in localized food searching efforts. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection

<div> <div> <div> <p>Mycobacteriophages are the viruses that infect mycobacteria. Due to the high death rate and antibiotic-resistant strains, phage therapy is considered to be a promising treatment of tuberculosis. Current understanding of phage-bacteria interaction is abstracted as phage lytic and lysogenic life cycles. However, bacterial physiology may impact phage life cycles and bacterial cells with different physiology may have different responses to phage infection. In order to improve the understanding of phage-bacteria interaction and update phage therapy strategy, the impact of mycobacterial physiology on mycobacteriophage life cycles was studied in this research. In this research, a mass spectrometry-based method was first developed to study phage proteins in phage-bacteria mixture. Then five mycobacteriophages isolated at Purdue University were selected to infect exponential and stationary <i>Mycobacterium smegmatis</i> (<i>M. smegmatis</i>) cell cultures. Growth curves of the <i>M. smegmatis</i> cell cultures infected by the five phages were determined. Proteomics and lipidomics of the <i>M. smegmatis</i> cells cultures infected by phages FrenchFry and MrGordo were analyzed by mass spectrometry. The correlations between individual proteins/lipids and the experimental factors (bacterial growth phases, phages and phage infection time) were studied by developing linear regression models using SAS. The mass spectrometry-based method was proved to be able to detect phage proteins other than the structural proteins. It also verified the phage protein annotation that had been accomplished <i>in silico</i>. X! Tandem and a database consisting of six frame translation of the phage genome and the annotated proteins of <i>M. smegmatis</i> were the optimal option for analyzing mass spectra data of phage-bacteria mixture. The growth curves of the <i>M. smegmatis</i> infected by the phages displayed that growth of exponential <i>M. smegmatis</i> cell cultures were depressed by phages (except FrenchFry) and stationary <i>M. smegmatis</i> cell cultures were not actively lysed by any of the phages. The proteomics results showed that MrGrodo infection impacted more proteins than other factors did. Exponential phase up-regulated proteins involved in cell division. Stationary phase up-regulated proteins that may change cell surface properties. FrenchFry up-regulated LuxR protein. Infection time up-regulated the proteins associated with mycobacterial virulence. The lipidomics results indicated that growth phases impacted the most lipids. Phage infection time increased the amount of the lipids related to mycobacterial virulence. In summary, the mass spectrometry-based method developed in this research can be employed to study phage proteins in phage-bacteria mixture and verify phage genome annotation. Mycobacterial physiology alters mycobacteriophage life cycles. Phage-bacteria interaction is the interaction between the two populations instead of between an individual phage particle and an individual bacterial cell. Virulence of <i>M. smegmatis</i> improves as a response to phage infection.</p></div></div></div>

With increased resource development on the western Arctic coastal plain of Alaska (especially within the oil extraction industry) it is important to understand the basic life history attributes of whitefish stocks in the region in order to ensure appropriate management. These fish are a crucial part of subsistence harvests for native Alaskans. Multiple forms of the whitefish least cisco (Coregonus sardinella) have been described based on both appearance and life history traits. Two major forms of least cisco have been mentioned in the literature: a larger normal amphidromous form with fork lengths of approximately 420 mm and a dwarf lake resident form with lengths up to 230 mm. However, there is considerable evidence for additional forms and life history strategies of least cisco. I investigated the relationship between migratory behavior and selected physical traits of least cisco in six lakes and one brackish lagoon in the western Arctic coastal plain of Alaska. I used electron microprobe technology to determine the levels of Sr and Ca in the otoliths of 258 least cisco in order to resolve their marine migratory life history. I also investigated the relationship between migratory behavior and the numbers of gill rakers, lateral line scales, anal rays and dorsal rays as well as condition factor. The vast majority of least cisco captured in these sites were normal in form, yet only ~12% of all samples yielded any sign of sea-run behavior. Evidence for migratory behavior was low even for sites within close proximity to brackish waters. Fish exhibiting marine migratory behavior tended to make their first migrations to sea before age three (mean=2.6 years), although fish in one coastal site (Joeb's) averaged over 5 years of age at first marine visit. There was some evidence of higher condition factors for fish with sea-run migratory experience. There were significant differences in lateral line and dorsal ray numbers among sites but none for anal rays or gill rakers. Variability in all of these characters was high, and fish from coastal sites tended to have greater variability than those from inland sites. Only dorsal rays showed significant differences in meristic traits between sea-run and resident least cisco. These results suggest that least cisco exhibit high variability in physical traits. Also, least cisco appear to be flexible in their use of the marine environment, even within similar forms in the same lake. Some of the most basic life history characteristics of least cisco remain uncertain. With increased resource extraction occurring on the western Arctic coastal plain of Alaska, it is important to continue to investigate these and other life history strategies so as to ensure a sustainable fishery for native inhabitants of the region. / Graduation date: 2004

No description available.

[Truncated abstract] Most ecological research investigates the demography of organisms, which can be summarised by their population dynamics and structure. Population dynamics are the rates of birth, growth, reproduction and survival of individuals, which determine the number of individuals in different stage classes, or, the population structure. Understanding the demography of organisms is particularly difficult, and requires the application of different methods of investigation. A number of methods of investigation are required because each can only investigate particular aspects of population demography, and is subject to problems of inaccuracy and bias. Thus, population demography is best understood by simultaneously collecting complimentary data using different methods of analysis to quantify how and why the dynamics and structure of populations change with their environment. The need for complimentary methods of investigation to understand population demography is even greater for organisms that have complex life histories, such as corals. The life histories of corals are particularly complex because they display a variety of modes of sexual and asexual reproduction, and their rates of growth, reproduction and survival are strongly influenced by the size of the individual, which can change rapidly. Additionally, the rates of sexual recruitment to populations of corals are notoriously variable in space and time. Thus, corals are an ideal model to investigate the usefulness of combining methods of analysis to better understand the demography of organisms. In this thesis I demonstrate that combining data from a number of methods of analysis provides a much better understanding of the demography of populations of the mushroom coral Fungia fungites that were exposed to contrasting regimes of disturbance. I used methods of analysis that produce unique and complimentary results, in the form of genetic, size-structure, life history and experimental data. Genetic data confirmed that I was correctly identifying life history stages of polyps, indicated the extent to which a stock-recruitment relationship existed between the sexual recruits and the adult polyps at each population, and provided an estimate of the relative contribution of asexual recruitment to population maintenance. Changes in the size-structures of populations were quantified to determine the effects of different regimes of disturbance, and these changes in population structure were explained by quantifying the life history traits of polyps and their rates of transition through their life cycle. An experimental manipulation was conducted to specifically quantify the effects of sedimentation on the rates of survival and asexual recruitment of polyps, because sedimentation was an important disturbance whose effects were confounded by additional variables. Together, the set of complimentary data provided a good understanding of population demography in the context of varying levels of exposure to certain disturbances, and enabled the best possible predictions about the future of each population under a variety of conditions

This thesis investigates the representation of the human life course in Old English poetry. It attends to constructions of the lifespan as a durational unit, as well as the ‘stages’ or discrete age-related experiences which together form patterns for life development, shared across a diverse range of texts. Throughout this study, the importance of close-reading is emphasised; the bulk of the analysis is concerned with issues of style, lexis and narrative. By these means, it becomes possible to perceive how concepts of the human life course shade into other networks of meaning: these include ideas of ensoulment and embodiment, life experiences of non-human entities, wider narrative patterns which impact representations of life progression, mechanisms and hierarchies of social role and communal existence, and systems of memory collection and the nurturing of ‘wisdom’. The introductory chapter addresses various possible modes of ‘life course’ structuring, in both Anglo-Saxon writings and modern scholarly traditions. Latin and Old English vocabularies of ageing are summarised and an overview is given of previous scholarship attendant on the Anglo-Saxon material. The following three chapters of the thesis then assess representations of different parts of the life course in different groups of texts. The second chapter is concerned with depictions of early life in the Exeter Book Riddles; it contends that these texts have been unduly passed over in discussions of ageing in Old English, seemingly due to their (mostly) non-human subjects. The third chapter addresses the treatment of early and late adulthood in the verse holy lives Andreas, Guthlac A, Juliana and Judith: it is in this chapter that concepts of the life course most clearly intersect with issues of social organisation. The fourth chapter is concerned with the characterisation of old age in Beowulf and Cynewulf’s epilogue to Elene, alongside other texts; the concept of ‘wisdom’ acquired through experience is closely scrutinised, and the verbal and poetic elements of good judgment are elucidated. This thesis concludes that Old English poetry presents human ageing in a manner which encompasses a diverse range of experiences and interrelates with a multitude of wider conceptual frameworks. As such, the texts do not subscribe neatly to an ‘ages of man’ idea. Nonetheless, attention paid to the patterns of human ageing which do emerge from the poems can facilitate more sensitive and productive readings of the texts themselves. The thesis closes with some examples of passages which may be newly interpreted and appreciated in the light of how the life course is conceived across the Old English poetic corpus.