Thesis (Ph.D.)--Tufts University, 2003. / Adviser: L. Michael Romero. Submitted to the Dept. of Biology. Includes bibliographical references (leaves 158-180). Access restricted to members of the Tufts University community. Also available via the World Wide Web;

Diss. (sammanfattning) Uppsala : Univ., 2007. / Härtill 5 uppsatser.

Thesis (Ph.D.) -- La Trobe University, 2006. / "A thesis submitted in total fulfilment of the requirements for the degree of Doctor of Philosophy, Dept. of Zoology, School of Life Sciences, La Trobe University". Research. Includes bibliographical references (p. 445-481). Also available via the World Wide Web.

Thesis (Ph. D.)--University of Melbourne, 2002. / Includes bibliographical references (leaves 156-172).

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.

‘Eco-evolutionary feedbacks’ occur when evolution of organismal traits causes environmental change that drives further evolution. Predator and prey interactions provide good examples of eco-evolutionary feedbacks. Here I examine the potential for eco-evolutionary feedbacks between three-spined sticklebacks (Gasterosteus aculeatus, hereafter ‘stickleback’) and their zooplankton prey in lochs (lakes) on the Scottish island of North Uist. Many lochs on the island were colonised by sticklebacks after the last glaciation, approximately 10,000-15,000 years ago. Previous work has shown that sticklebacks in different lochs have diverged greatly from each other in response to local environments. On the other hand, apart from several very old studies on the occurrence of some zooplankton species, there have been no previous in depth studies on the population dynamics of zooplankton on North Uist. I investigated first the diversity and abundance of zooplankton groups and the most common species across all North Uist lochs. Thirty-nine species were classified from three main groups (Rotifera, Cladocera and Copepoda). Species abundance in the presence of fish was relatively more even, while the abundance of zooplankton groups was not generally related to fish presence except for Cladocera in a subset of locations. The effects of predation on the life-history of zooplankton were also examined by comparing reproductive traits of the dominant cladoceran species (Bosmina and Daphnia) in lochs with and without fish. Cladocerans in lochs with fish have more rapid reproductive cycles and higher fecundity parameters, probably in response to the increased threat of predation. These effects remain evident in Bosmina after they have been raised through three generations in the laboratory, supporting the hypothesis that they have a genetic basis and are not a plastic response to predator presence. Life-history variables of cladocerans were also related to abiotic and biotic variation among lochs, including depth, pH, chlorophyll levels and the concentration of alkaline metals. I also demonstrate that stickleback have diversified greatly among lochs in functional trophic traits that determine the efficiency of feeding on different types of prey, which could affect total primary production and the structure of prey communities. Ancestral stickleback populations have adapted according to the type of habitat colonised. Fish feed on benthic prey in shallow lochs, which requires greater effort for successful foraging than that required by fish that feed on planktonic prey. I found that variation in stickleback trophic traits was related to both abiotic and biotic variation among lochs, including loch depth and the mean contributions of planktonic and benthic prey to diet. The results presented in this thesis suggest the possibility of eco-evolutionary feedbacks in these simple ecosystems on North Uist based on the significant responses in fish and zooplankton communities. The thesis also provides a basis for further studies on fish-zooplankton interactions on North Uist and contributes to the wider body of knowledge concerning the relevance of natural variation in shaping the foraging mechanisms of animals.

Submitted by Anaclaudia Mattos Villalba (anaclaudiamattosvillalba@gmail.com) on 2016-04-06T20:20:17Z No. of bitstreams: 1 Dissertacao-final-08-01-15-Cintia-Ramm.pdf: 712039 bytes, checksum: 71ed21f23bcc12921d754ed1b5004e9f (MD5) / Approved for entry into archive by cleuza maria medina dos santos (cleuzamai@yahoo.com.br) on 2016-04-18T20:06:20Z (GMT) No. of bitstreams: 1 Dissertacao-final-08-01-15-Cintia-Ramm.pdf: 712039 bytes, checksum: 71ed21f23bcc12921d754ed1b5004e9f (MD5) / Made available in DSpace on 2016-04-18T20:06:21Z (GMT). No. of bitstreams: 1 Dissertacao-final-08-01-15-Cintia-Ramm.pdf: 712039 bytes, checksum: 71ed21f23bcc12921d754ed1b5004e9f (MD5) Previous issue date: 2015 / A capivara Hydrochaeris hydrochaeris é um roedor de grande porte e semiaquático. A espécie ocorre em vários ambientes, podendo ocorrer em regiões com alto grau de influencia antrópica. A BR-471 que corta longitudinalmente a ESEC Taim, causa impacto localmente na região, por estar ocasionando prejuízos à fauna e a flora, em função dos atropelamentos de capivaras ao longo da reserva. Nesta região também vem sendo utilizados pesticidas e herbicidas, que podem estar contribuindo com a presença de metais. Estes metais podem se depositar no sedimento e na coluna d’água afetando direta ou indiretamente os organismos. No entanto as capivaras estão sujeitas aos efeitos da bioacumulação destes possíveis contaminantes, adquiridos através da ingestão de plantas contaminadas por metais. Com isso, o objetivo desse trabalho é avaliar os níveis de contaminação por metais pesados em tecidos de capivaras (Hydrochaeris hydrochaeris) mortas por atropelamentos na Br-471 Sul do Rio Grande do Sul. Para determinar as concentrações de metais (Ag, Cd, Cu, Pb, e Zn) em diferentes tecidos (fígado, rim, gordura, músculo) pelo e conteúdo estomacal de capivara, foram realizadas coletas mensais ao longo de um ano. As amostragens dos animais mortos serão feitas através de necropsia, as amostras e serão acondicionadas em tubos de plástico e posteriormente congeladas. Após, essas amostras serão pesadas, secas e digeridas em ácido nítrico e diluídas em água MilliQ. As concentrações de Ag, Cd, Cu, Pb, e Zn serão determinados por espectrofotometria de absorção atômica. Os dados serão expressos como média ± erro padrão. As médias dos metais dos tecidos de machos e fêmeas serão comparadas através de Analise de Variância de duas vias (ANOVA), seguida de teste a posterior de Tukey, com significância de 5%. Os resultados, demonstraram que a concentração de prata foi menor na primavera em relação às outras estações do ano nas amostras (P<0,05), não houve variação significativa (P< 0,05) na concentração de cádmio nas amostras, a concentração de chumbo na primavera foi maior em todas as amostras (P< 0,05), a concentração de cobre no inverno e no outono foi significativamente menor que o verão e a primavera (p< 0,05), a concentração de zinco não teve variação ao longo do ano (P< 0,05). O Cd, Ag e o Pb não tiveram variação significativa ao longo do ano no sedimento (P<0,05), já o Cu foi presente no sedimento na primavera, e o Zn foi maior no outono e inverno. (P<0,05). Os resultados deste trabalho demonstraram que as capivaras estão contaminadas por metais não essenciais na Estação Ecológica do Taim. Além disso, podemos sugerir a utilização de pelo para o monitoramento de contaminação da capivara por metais. / The capybara Hydrochaeris Hydrochaeris is a rodent large and semiaquático. The species occurs in various environments and can occur in regions with high anthropogenic influences. The BR- 471 that cuts along the ESEC Taim, impacts locally in the region, to be causing damage to fauna and flora, according to the roadkill capybaras along the reservation. This region has also been used herbicides and pesticides that may be contributing to the presence of metals. These metals can be deposited in the sediment and the water column affecting directly or indirectly the bodies. However capybaras are subject to the effects of bioaccumulation of these possible contaminants, acquired through eating plants contaminated by metals. Thus, the aim of this study is to assess the levels of heavy metal contamination in tissue capybaras (Hydrochoerus hydrochaeris) killed by being run over in the BR-471 South Rio Grande do Sul. To determine the concentrations of metals (Ag, Cd, Cu , Pb, and Zn) in different tissues (liver, kidney, fat, muscle) and the stomach contents of capybara, monthly samples were taken over a year. Samples of the dead animals will be made through autopsy, samples and will be placed in plastic tubes and subsequently frozen. After these samples are weighed, dried and digested in nitric acid and diluted in MilliQ water. The Ag concentrations of Cd, Cu, Pb, and Zn are determined by atomic absorption spectrophotometry. The data are expressed as mean ± standard error. The means of the metals of male and female tissues will be compared by analysis of two-way variance (ANOVA) followed by Tukey test later, with 5% significance. The results showed that the silver concentration was lower in the spring relative to the other seasons in samples (P <0.05), there was no significant difference (P <0.05) in cadmium concentration in the samples, the concentration lead spring was higher in all samples (P <0.05), the concentration of copper in the winter and autumn was significantly lower than the spring and summer (p <0.05), the concentration of zinc was not variation throughout the year (P <0.05). Cd, Ag and Pb have not changed throughout the year in the sediment (P <0.05), whereas the Cu was present in the sediment in the spring, and Zn was higher in autumn and winter. (P <0.05). These results demonstrated that capybaras are contaminated by non-essential metals in the Taim Ecological Station. In addition, we suggest the use of at for contamination monitoring of the capybara for metals.

Cardiovascular responses evoked during forced submersion enable the Pekin duck (Anas platyrhynchos) to survive protracted periods of asphyxia. The responses include an extraordinary bradycardia and intense peripheral vasoconstriction with the result that blood flow is favoured to those organs most susceptible to lack of oxygen. These adjustments appear to be mediated via the caudal brainstem following stimulation of peripheral and central arterial chemoreceptors. The minor role that baroreceptors play in the generation of these responses was demonstrated by the persistence of the cardiovascular changes following peripheral arterial baroreceptor denervation. Isolation of the cephalic circulation from the systemic circulation enabled a series of experiments to assess the relative contributions from peripheral chemoreceptors, located in the carotid bodies, and from unidentified central chemoreceptors within the cranial circulation. A declining arterial P0₂ in the systemic circulation appeared especially potent in evoking bradycardia during submersion. Increased arterial PC0₂, likewise, resulted in a reduced heart rate. Similar changes in the blood gas levels of the cephalic circulation did not elicit significant bradycardia. However, both receptor groups responded to arterial hypoxic hypercapnia by activating substantial reduction in peripheral blood flow, as reflected by the rise in hind limb vascular resistance. Although baroreceptors may continue to mitigate changes in arterial blood pressure and cause some change in heart rate and vascular resistance, chemoreceptors appear to be predominantly responsible for the changes during submersion. The cardiac response to chemoreceptor stimulation during submersion was discovered to habituate following repetitive diving. Habituation was so pronounced in some ducks that after several training sessions the bradycardia during 40-second forced dives was abolished. Habituation of the cardiac response appeared dependent on the intensity of chemoreceptor stimulation. With severe arterial hypoxia, produced by either prolonging dive times or by reducing the pre-dive inspired oxygen content, little or no cardiac habituation was observed. Tests were conducted to demonstrate efficacy of the cardioinhibitory efferent discharge. Maintained sensitivity of chemoreceptors was suggested by the lack of change in oxygen breathing tests before and after training. Furthermore, the persistence of stimulus intensity was established and these observations led to the suggestion that the locus of habituation is within the CNS. The demonstration that the level of bradycardia was dependent on arterial P0₂ in both naive and habituated animals argues against the contention that the diving response is a fear response. Further evidence against this view was provided by the demonstration that the diving response remains essentially intact following transection in the rostral mesencephalon below the level of the hypothalamus. It is concluded that chemoreceptor-driven cardiovascular changes evoked as part of the diving response are mediated by regions of the CNS below the rostral brainstem. Modification of these responses can be produced in the intact animal by simple forms of learning. However, it remains uncertain at what level this influence arises. / Science, Faculty of / Zoology, Department of / Graduate

During sustained exercise, working muscles must be supplied with adequate kinds and amounts of exogenous fuels, and the delivery rates of oxygen and oxidizable substrates should be matched. The study of metabolite fluxes and their regulation is therefore critical to the understanding of exercise metabolism. Lactate has received renewed attention from physiologists and biochemists with the realization that it is not only an end product of glycolysis, but also an important fuel for aerobic work. As an oxidizable fuel, this substrate may provide some performance advantage over other fuels such as glucose and free fatty acids. The goals of this thesis were: 1) to determine whether endurance-adapted animals can support higher plasma lactate turnover rates than sedentary animals; and 2) to investigate the major factors involved in the regulation of plasma metabolite turnover at the whole-organism level - using lactate as a model. Lactate turnover rates were measured by bolus injection of [U-¹⁴C]lactate in skipjack tuna, Katsuwonus pelamis, and in thoroughbred racehorses, Equus caballus. In tuna, turnover rates ranged from 112 to 431 umol min⁻¹ kg⁻¹ and they were positively correlated with lactate concentration (slope = 15.1, r = 0.92). This teleost is able to support higher plasma lactate turnover rates than expected for a mammalian lower temperature, and lactate is probably an important oxidizable fuel in this species. For comparative purposes, resting turnover rates of lactate and glucose were plotted versus body mass on a log-log scale for a wide range of mammalian species. These plots were linear, and they showed the same slope as the classic body mass vs metabolic rate relationship. Thoroughbred horses are likely to have an aerobic scope of 40-fold or more. One of their main physiological adaptations to exercise is the ability to increase hematocrit by more than one and a half-fold in response to exercise. In the present study, this adjustment allowed them to reach an A-V difference in 0₂ content of more than 23 vol% during maximal exercise, a much higher value than other mammals. Their lactate turnover rate and cardiac output were measured at rest and two levels of submaximal exercise (45 and 55 V0₂ max) to investigate the relationship between cardiovascular adjustments on plasma lactate turnover rate. Cardiac output ranged from 106 to 571 ml min⁻¹ kg⁻¹, and mean lactate turnover rate from 9.3 at rest, to 75.9 umol min⁻¹ kg⁻¹ at 55% V0₂ max. In contrast with the situation found in tuna, the lactate turnover rates of thoroughbreds were not elevated compared with other mammals, showing that the metabolic adaptations of these outstanding athletes do not include the ability to sustain higher lactate fluxes than sedentary animals. In horses, the contribution of plasma lactate oxidation to V0₂ is minimal, and this substrate is not an important oxidative fuel; lipid oxidation may represent their major pathway for aerobic energy production during exercise. The ability to oxidize plasma lactate at high rates is therefore not necessarily required for the "elite" performance of endurance exercise. This study also shows that both, plasma lactate concentration and cardiac output are positively correlated with turnover rate. The correlation between cardiac output and lactate turnover rate is independent of the relationship between plasma lactate concentration and turnover rate. Plasma metabolite concentration and cardiac output can be regulators of plasma metabolite turnover rate. It is proposed that these two variables are, respectively, the fine and coarse controls for flux rate adjustments during exercise. / Science, Faculty of / Zoology, Department of / Graduate

In this study, the structure and function of gonadotropin-releasing hormone (GnRH) in different vertebrate species, in the classes Aves, Reptilia and Pisces was investigated. Acetic acid extracts were subjected to gel filtration chromatography and semipreparative high performance liquid chromatography (HPLC) to partially purify the GnRHs. The GnRH immunoreactivity was then characterized by analytical HPLC, and by assaying HPLC fractions by radioimmunoassay with region-specific antisera generated against mammalian GnRH, Gln⁸-GnRH and Trp⁷,Leu⁸-GnRH and assessing luteinizing hormone (LH)-releasing activity of fractions in a chicken dispersed anterior pituitary cell bioassay. Five GnRH molecular forms have thusfar been structurally characterized in vertebrate brain. In mammals a GnRH with the structure pGlu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH₂ has been demonstrated in the hypothalamus (Matsuo et al., 1971; Burgus et al., 1972). Gln⁸-GnRH and His⁵,Trp⁷,Tyr⁸-GnRH were present in chicken hypothalamus (King and Millar, 1982a, 1982c; Miyamoto et al., 1983, 1984), Trp⁷,Leu⁸-GnRH in salmon brain (Sherwood et al., 1983) and Tyr³,Leu⁵,Glu⁶,Trp⁷,Lys⁸-GnRH in lamprey brain (Sherwood et al., 1986). In ostrich (Struthio camelus) hypothalamus two GnRHs with identical properties to Gln⁸-GnRH and His⁵,Trp⁷,Tyr⁸-GnRH have been demonstrated, as well as four other LR-releasing factors with different chromatographic and immunological properties to any of the known naturally-occurring GnRHs. Since Gln⁸-GnRH and His⁵,Trp⁷,Tyr⁸-GnRH were also present in chicken hypothalamus it appears likely that these two GnRHs occur in all birds. In alligator (Alligator mississippiensis) brain only two GnRHs were detected. These forms co-eluted with Gln⁸-GnRH and His⁵,Trp⁷,Tyr⁸-GnRH in two HPLC systems. They cross-reacted similarly to the two synthetic peptides with antisera directed against mammalian GnRH and Gln⁸-GnRH and released LH from chicken dispersed anterior pituitary cells in a similar manner to the synthetic peptides. The Archosaurs (alligators and crocodiles) are believed to be closely related to birds and therefore it seems likely that they should have identical GnRHs. In skink (Calcides ocellatus tiligugu) brain one GnRH, which co-eluted with His⁵,Trp⁷,Tyr⁸-GnRH, was demonstrated. Two other lizards (Cordylis nigra and Pordarcis s. sicula) have been studied (Powell et al., 1985; R.C. Powell, G. Ciarcia, V. Lance, R.P. Millar and J.A. King, submitted). In c. nigra four immunoreactive GnRHs were detected, two of which co-eluted released chicken LH similarly to, Trp⁷,Leu⁸-GnRH and with, and His⁵,Trp⁷,Tyr⁸-GnRH. In P. s. sicula a GnRH molecular form similar to Trp⁷,Leu⁸-GnRH occurred as well as two novel GnRHs. It thus appears that Gln⁸-GnRH does not occur in lower reptiles, but His⁵,Trp⁷,Tyr⁸-GnRH and/or Trp⁷,Leu⁸-GnRH do. His⁵,Trp⁷,Tyr⁸-GnRH appears to he a widespread GnRH, occurring in vertebrates as diverse as birds and elasmobranch fish. In dogfish (Poroderma africanum) brain seven factors, which stimulated release of LH from chicken dispersed anterior pituitary cells, were separated on analytical HPLC. Two of these factors were partially characterized as Trp⁷,Leu⁸-GnRH and His⁵,Trp⁷,Tyr⁸-GnRH. Three of the other forms cross-reacted with GnRH antisera, but appear to be novel GnRHs. In teleost (Coris julis) brain two GnRHs similar to Trp⁷,Leu⁸-GnRH and His⁵,Trp⁷,Tyr⁸-GnRH were present. These two GnRHs therefore appear to occur in both fish species studied. Trp⁷,Leu⁸-GnRH is widespread amongst teleost fish (Jackson and Pan, 1983; Sherwood et al., 1983; Breton et al., 1984; Sherwood et al., 1984; King and Millar, 1985). From these data it seems evident that the mammalian GnRH molecular form occurs only in mammals and amphibians, Gln⁸-GnRH in birds and higher reptiles, and Trp⁷,Leu⁸-GnRH in gnathostomes. His⁵,Trp⁷, Tyr⁸-GnRH appears to he present in numerous different vertebrates. Tyr³,Leu⁵,Glu⁶,Trp⁷,Lys⁸-GnRH has thus far only been detected in lamprey brain. A number of novel GnRHs, whose structures have not been elucidated are present.