Thesis (Ph.D)--Boston University / Characteristics of deoxyribonuclease II from calf thymus and spleen were described and verified by the following experimental procedures. Nuclei from calf thymus were prepared free of cytoplasm both by washing homogenized tissue in sucrose solutions, and by density gradient centrifugation in organic solvents. The action of the enzyme from nuclei and from a thymus homogenate was found to be similar when measured by light scattering and hyperchromic shift. Deoxyribonuclease II from calf spleen was purified by ammonium sulfate precipitation. Further purification of the enzyme on column chromatography resulted in fractions similar to those reported in the literature. The effect of sodium sulfate on the activity of splenic DNase II, purified by ammonium sulfate precipitation, was measured by the production of acid-soluble nucleotides from deoxyribonucleic acid during hydrolysis. The effect of the sulfate ion was also measured by viscometry, as was the effect of magnesium chloride, manganese chloride, sodium citrate and iodoacetic acid. The substances were all found to be inhibitory, which is in agreement with the results reported in the literature. Deoxyribonucleases active at an acid pH were extracted from representatives of four invertebrate phyla (Echinodermata, Mollusca, Arthropoda and Annelida) and compared with vertebrate deoxyribonuclease II with respect to ionic requirements and pH optima. [TRUNCATED]

A main challenge in evolutionary ecology is to elaborate the main ecological factors that vary in a study system and analyse how those factors shape the phenotype of organisms in their natural environment. These ecological variables can have complex effects since most life history traits are correlated. Here I examined the effects of ecological factors on life history traits, and the relationship among life history traits of North Uist three-spined stickleback, Gasterosteus aculeatus (hereafter stickleback). Both abiotic and biotic factors that are commonly measured in aquatic systems, and are known to vary greatly between North Uist lochs, were examined. The traits analysed were body size, age and size at maturation, proportion of fish over one year old, and the fecundity rate. My results showed that there was strong variation in water chemistry and inter-specific competition among the lochs on North Uist. Lochs on the west side of the island were characterised by higher sodium and calcium ion concentrations, higher pH and conductivity, and increased inter-specific competition. As a result, western populations had a faster absolute growth rate, larger body size, and a higher proportion of older fish, indicative of a longer life span. Although western populations had a larger body size, they tended to mature later with a smaller gonadosomatic index. They also favoured a larger number of eggs, but with a smaller egg size. Variations within population showed that larger females had greater fecundity but small egg size. Both plasticity and evolution appear to have contributed to these life history variations. Overall, variation in life history of North Uist stickleback was largely related to measures of resources availability and interspecific competition, except for egg size which was mostly associated with variation in predator density.

The processes driving and maintaining variable immune responses are poorly understood compared with other aspects of an organism’s ecology. This is particularly true from an evolutionary perspective, as the evolutionary relationships between immune responses and other traits and processes in nature remain inadequately explored. I investigated these associations in this thesis using the three-spined stickleback system as an evolutionary and immunological model. I combined sampling of wild individuals with genomic analyses to demonstrate phenotypic and genomic associations between immune responses and life history evolution across multiple populations. I also observe how experimental changes in daylength, a seasonal cue, modulate immune responses and increase parasite susceptibility in a controlled laboratory experiment. These findings occur independently of natural variation in parasite resistance. Stickleback are also a model for studies of speciation. I used sampling of wild hybrids to assess the significance of immune variation in postzygotic isolating mechanisms between diverging ecotypes; although my findings suggest a minor role. Finally, I demonstrate that genomic responses to parasitism and abiotic environmental variation are repeatable across independent, intercontinental adaptive radiation events in sticklebacks; conferring a repeatability of the evolutionary relationships of immune variation documented in this thesis. The findings within this thesis therefore provide novel insights into poorly explored or open areas of research regarding how variable immune responses evolve in nature.

Understanding the natural behaviour and coexistence of species is important for the conservation of intact ecosystems, and behavioural studies can enhance our knowledge of processes such as communication and competition. I investigated the social dynamics and scent-marking behaviour of spotted hyaenas (Crocuta crocuta), and the occurrence of interspecific olfactory eavesdropping among African mammals, within the Okavango Delta ecosystem of Botswana. First, social network analysis found that the hyaena population was comprised of five main clans that maintained territories but whose home ranges overlapped considerably. Scavenging at large carcasses involved associations between individuals from different clans and resulted in relative tolerance toward territorial intruders. Second, observations of communal latrine use found that latrines are likely involved in territorial advertisement by hyaena clans, and cyclical patterns of latrine growth and decline were linked to annual rainfall. Third, a translocation experiment showed that hyaena scats appear to be less important for hyaena communication than other cues associated with latrines, especially as hyaenas did not differ in their behaviour towards scat originating from latrines located in resident versus non-resident clan home ranges. Heterospecific mammals investigated, scent-marked, and were vigilant at hyaena latrines, suggesting a potential function for hyaena latrines in interspecific eavesdropping and/or communication. Fourth, a urine presentation experiment found that the investigation of sympatric predator urine by African mammals stimulated vigilance behaviour, suggesting that olfactory signals provide information about predation risk. Hyaenas exhibited context-specific differences in behaviour towards predator urine: they were more likely to investigate urine samples alongside indicators of predator activity (i.e. carrion odour, carcasses) and were most likely to exhibit vigilance at carcasses when exposed to urine from lions and wild dogs. This study greatly enhanced our understanding of spotted hyaena behaviour within the Okavango Delta, an important ecosystem for the conservation of African large predators. Furthermore, this study provided the first experimental evidence of the role of hyaena scats in intraspecific communication and interspecific olfactory eavesdropping at latrines. My research findings regarding the population’s clan structure and home ranges will form the foundation for subsequent investigation into human-wildlife conflict in the study area. Furthermore, the results from two scent experiments shed light on the potential importance of olfactory signals for mediating interspecific interactions among African mammals, particularly among large predators.

Population fragmentation and subsequent isolation in different refugia during the glacial advances of the Pleistocene are believed to have had a significant impact on current levels of genetic and morphological diversity. Despite the importance of these glacial refugia for biodiversity, our understanding of their distribution on the northwestern coast of North America and their relative impact on populations remains limited. As the most isolated group of islands in the Pacific Northwest, Haida Gwaii has been the subject of intense study both from the perspective of its complex glacial history and endemic flora and fauna. The ubiquitous presence of glacial features on this archipelago points to extensive ice cover during the late Wisconsin (Fraser glaciation) and populations which could only have become established postglacially. However, the large assemblage of unique mammalian and avian fauna found on Haida Gwaii has led to suggestions that these divergent vertebrates actually evolved through long isolation by continuously inhabiting these islands or nearby regions throughout the last glacial maximum. To assess Haida Gwaii’s role as a glacial refugium and the relictual status of its endemic black bear (Ursus americanus), marten (Martes americana), short-tailed weasel (Mustela erminea), caribou (Rangifer tarandus) and Saw-whet Owl (Aegolius acadicus), a broad phylogeographic study using sequence comparisons of the mitochondrial gene cytochrome b was undertaken. Phylogeographic structure was observed in the black bear (n= 33), marten (n= 18) and short-tailed weasel (n= 32). Based on parsimony, maximum likelihood, and neighbour-joining analyses of 719 bp of cytochrome b, two geographically structured black bear lineages were unambiguously identified: 1) a continental lineage found in the Yukon, Alberta, Alaska, Montana and Pennsylvania (americanus) and mainland BC (americanus and cinnamomum) and 2) a coastal lineage found on Haida Gwaii (carlottae), Vancouver Island (vancouveri) and the Olympic Peninsula (altifrontalis). The two lineages were defined by 24 synapomorphies and an average sequence divergence of 3.6%. Average intralineage divergence was 0.1%. Similarly, two geographically structured lineages, continental and coastal, were also identified in marten using the same types of analyses on 3II bp of cytochrome b. The continental lineage included marten from mainland BC (caurina and abietinoides) and Newfoundland (atrata) whereas the coastal lineage included marten from Haida Gwaii (nesophila) and Vancouver Island (vancouverensis). The two lineages were defined by three synapomorphies and an average sequence divergence of 1.2%. Average intralineage divergence was 1%. Phylogeographic structure was also observed in the short-tailed weasel using 148 to 673 bp of cytochrome b. Three major lineages were identified and named according to their putative refugial source areas: Beringia, which included weasels from Japan (orientalis) and the Yukon (arctica), a continental or southern source, which encompassed weasels from mainland BC (richardsonii, invicta,fallenda), Manitoba (bangsi), and Ontario (cicognanii), and Haida Gwaii which included only those weasels from Haida Gwaii (haidarum). Short-tailed weasels from Vancouver Island (anguinae) and some areas along the coast demonstrated an affinity to both southern and Haida Gwaii weasels. Relative to the continental lineage, the coastal lineage was defined by 13 synapomorphies; the Beringian lineage was defined by 10 synapomorphies. Average sequence divergence was 2.5 % and 2.2% respectively. Divergence between the coastal weasels and Beringian weasels was 2.4%. There was little mtDNA diversity within the coastal lineage as the average intralineage divergence was 0.8%. Little or no phylogeographic structure was observed in the caribou and Saw-whet Owl. Of the 313 bp examined in two barren ground caribou (granti) and seven woodland caribou (four tarandus and three dawsoni), three tarandus and two dawsoni formed a lineage defined by one synapomorphy. The two barren ground, one tarandus, and one dawsoni were excluded from this lineage by one to three substitutions. Similarly, little phylogeographic structure was observed in the Saw-whet Owl. Analyses of a 241 bp of cytochrome b sequenced from this species indicated no genetic divergence between individuals as far apart as Haida Gwaii (brooksi) and Manitoba (acadicus). The maximum divergence observed between individuals was 0.4%. The phylogeographic patterns from these five species have two major implications with regard to the issue of glacial refugia and the relictual status of the Haida Gwaii endemics: 1) With the possible exception of haidarum, the suite of morphological features characterizing the endemics carlottae, nesophila, dawsoni and brooksi appear to have been derived postglacially. In fact close genetic affinity of these endemic subspecies with adjacent conspecifics suggest that population fragmentation caused by glaciers has had little effect on morphological differentiation and that adaptation to local ecological environments has played a more influential role in their evolution. 2) Emerging data of a mid-Pleistocene split of many vertebrate taxa and the geographic distribution of these various generic lineages, including the black bear, marten and short-tailed weasel in this region cumulatively suggests that a refugium existed on the continental shelf off the central coast of British Columbia and was possibly part of a larger (or series of refugia) refugium which extended further north and south along this coast. Given the broad assemblage of taxa which might have persisted here during the last glaciation, this refugium was probably ecologically productive and as such, was likely to have been an important alternate source area for the postglacial recolonizarion of northwestern North America. / Graduate

No description available.

The purposes of this thesis were (1) to provide some knowledge of the herptiles and mammals of this area, (2) to clarify the distribution of many of these animals in this section of Texas, and (3) to provide additional ecological information about the area.

Thesis (M.A.)--Boston University / PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / The amount o serotonin, one of the biologically active amines, was determined in selected species of non-mammalian vertebrates - the dogfish Mustelus canis, the tautog Tautoga onitis, the turtle Pseudymys scripta elegans, and the chicken Gellus gallus. The extraction procedure employed was highly sensitive and specific. Contaminating indoles which occur naturally in tissues were removed before extraction by shaking with diethyl ether and adjusting the pH. Serotonin was then extracted with butanol from an alkaline, sodium chloride-saturated solution and re-extracted back into dilute acid. It was identified on a Farrand spectrophotofluorometer by its characteristic activation activation peak at 305 mu and fluorescence peak at 550 mu, and the amount present was determined. The range in chicken whole blood was found to be 10.3-19.4 ug. per ml. Under the conditions of the experiment, the major portion of chicken blood serotonin could not be shown to be contained in the thrombocytes. The range of serotonin in turtle whole blood was found to be .228-1.32 ug. per ml. Serotonin could not be demonstrated in the tautog or the dogfish. / 2031-01-01

No description available.

No description available.