Submitted by Franciele Moreira (francielemoreyra@gmail.com) on 2018-02-09T13:52:40Z No. of bitstreams: 2 Dissertação - Hyara Paula Fleuri Xavier - 2017.pdf: 1558991 bytes, checksum: 03535b693efa8cdc053f47c33646cd59 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Liliane Ferreira (ljuvencia30@gmail.com) on 2018-02-09T14:41:58Z (GMT) No. of bitstreams: 2 Dissertação - Hyara Paula Fleuri Xavier - 2017.pdf: 1558991 bytes, checksum: 03535b693efa8cdc053f47c33646cd59 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-02-09T14:41:58Z (GMT). No. of bitstreams: 2 Dissertação - Hyara Paula Fleuri Xavier - 2017.pdf: 1558991 bytes, checksum: 03535b693efa8cdc053f47c33646cd59 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2017-08-10 / Fundação de Amparo à Pesquisa do Estado de Goiás - FAPEG / The objective of this essay was to evaluate the use of guava extract processing as an antioxidant additive on the diet of Japanese quail matrices about the parameters on the matrices fertile performance on posture phase and the newborn quail parameters in the quality and internal health resulted from the eggs of these matrices. Three experiments were done in the School of Veterinary and Animal Science in the Federal University of Goiás (EVZ/UFG) and in all three of them, it was adopted the completely randomized design (CRD). In the first experiment, 384 Japanese quail matrices were used, 288 being females and 96 males, distributed in 4 groups, following the level of guava extract inclusion on the diet of the matrices, with a recurrence of 6 times each group, in a total of 12 females and 4 males in each recurrence. The levels of guava extract inclusion were 0,0%, 0,3%, 0,6% and 0,9%. In the second experiment, it were collected 162 eggs from each group during three days and at the end of the third day they were put in the incubator, in a total of 648 eggs. In the third experiment, 432 eggs were collected and put in the incubator in a factorial arrangement that considered two periods of preincubation storage – 216 eggs with nine days and 216 eggs with 3 days – and the four levels of guava extract inclusion on the diet of the matrices. The performance data results were submitted to the variance analysis and the quality data of the eggs were submitted to the regression analysis. The newborn quails quality parameters were submitted to the regression analysis. The hatch window were submitted to the Tukey’s test, the embryo diagnosis and the score percentage were assessed by Fisher’s exact test, the villus height analysis and intestinal crypt depth were submitted to the variance analysis. It was adopted in all the analysis 5% of probability. The use of guava extract has not influenced neither the birds’ performance nor the physicochemical quality of the eggs. In the second experiment, there was no statistical difference to the percentage of total hatch and the percentage of hatch/fertile, hatch window and the quality score of the newborn quails among the four levels of extract inclusion. The birth dispersal in the group with 0,0% of guava extract inclusion was lower than the other dispersions. 0,3% level of inclusion, the guava extract promoted improvements in the newborn quails intestinal health. In the third experiment, the guava extract inclusion was able to standardize the birth dispersal in both storage periods and promote the maintenance of the newborn quails resulted from the eggs stored for nine days. This study concludes that the use of the guava extract has not affected the matrices’ fertile performance and helped to standardize the hatch window as well as promoting intestinal health of the newborn quails. / Objetivou-se avaliar o uso do extrato de resíduo de goiaba como um antioxidante zootécnico nas dietas de matrizes de codornas Japonesas sobre os parâmetros de desempenho produtivo das matrizes em fase de postura, qualidade de ovos, incubação e parâmetros de qualidade e desenvolvimento intestinal das codornas neonatas oriundas de ovos dessas matrizes. Foram realizados três experimentos no aviário experimental da Escola de Veterinária e Zootecnia da Universidade Federal de Goiás (EVZ/UFG) e em todos adotou-se delineamento inteiramente casualizado (DIC). No experimento 1, foram utilizadas 384 matrizes de codornas Japonesas, sendo 288 fêmeas e 96 machos, distribuídos em 4 tratamento, de acordo com o nível de inclusão do extrato de goiaba na dieta das matrizes, com 6 repetições cada tratamento, num total de 12 fêmeas e 4 machos em cada repetição. Os níveis de inclusão do extrato de goiaba foram: 0,0%, 0,3%, 0,6% e 0,9%. No experimento 2, 162 ovos por tratamento foram coletados durante três dias e incubados ao final do terceiro dia, num total de 648 ovos. No experimento 3, 432 ovos foram coletados e incubados em esquema fatorial que considerava dois períodos de armazenamento pré incubação – 216 ovos com nove dias e 216 ovos com três dias – e os quatros níveis de inclusão do extrato de goiaba na dieta das matrizes. Os resultados dos dados de desempenho foram submetidos à análise de variância e os dados de qualidade de ovos foram submetidos à análise de regressão. Os parâmetros de qualidade das codornas neonatas foram submetidos à análise de regressão. As janelas de eclosão foram submetidas ao teste de Tukey, as análises de embriodiagnóstico e percentagem de escore foram avaliadas pelo teste exato de Fisher, as análises de altura de vilosidades e profundidade de criptas intestinais foram submetidas à análise de variância. Em todas as análises adotou-se 5% de probabilidade. A utilização do extrato de goiaba não influenciou o desempenho das aves nem a qualidade físico-química dos ovos. No experimento 2 não houve diferença estatística para percentagem de eclosão total e percentagem de eclosão/férteis, janela de eclosão e escore de qualidade das codornas neonatas entre os quatro níveis de inclusão do extrato. A dispersão dos nascimentos no tratamento com 0,0% de inclusão de extrato de goiaba foi menor do que as demais dispersões. Ao nível 0,3% de inclusão, o extrato de goiaba promoveu melhorias no desenvolvimento intestinal das codornas neonatas. No experimento 3, a inclusão do extrato de goiaba foi capaz de padronizar a dispersão dos nascimentos em ambos os períodos de armazenamento e promover a manutenção do desenvolvimento intestinal das codornas neonatas oriundas de ovos armazenados por nove dias. Conclui-se que o uso do extrato de goiaba não afetou o desempenho produtivo das matrizes e auxiliou na padronização das janelas de eclosão bem como no desenvolvimento intestinal das codornas neonatas.

Made available in DSpace on 2017-07-10T17:48:09Z (GMT). No. of bitstreams: 1 Leticia_Angelica_Pereira.pdf: 691022 bytes, checksum: 4ea817fecf3a460a2a24e9762b62f93b (MD5) Previous issue date: 2015-10-20 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This study aimed to evaluate the effect of garlic essential oil (Allium sativum) on the fertility rate and hatching of silver catfish eggs, Rhamdia quelen, artificially incubated. The research consisted of two experiments (I and II) at the Institute for Research in Environmental Aquaculture (InPAA), Toledo-PR, from october to december 2014. It used a randomly experimental design with the four treatments and five repetitions. The treatments consisted on the introduction of garlic essential oil on the incubators of fish eggs with the levels of 0; 5; 10 and 20 and 0; 1; 3 and 5 mg L-1 of oil, on experiments I and II respectively. The fertilization rate was determined after the closing of the blastopore, approximately 10 hours post-fertilization and the hatching rate was calculated 24 hours post-fertilization, when it was observed the larvae shedding egg. It used the standard morphological larvae to determine the normal rate, with the aid of a stereoscopic microscope. On the experiment I the dosage of 5 mg L-1 promoted the biggest (p<0.05) rates of fertilization and hatching of the eggs. At levels of 10 and 20 mg L-1 was death from all embryos within 10h after fertilization. In the second experiment the dosage of 5 mg L-1 promoted best fertilization rates (p<0.01) and hatching (p<0.05) compared to other essential oil concentrations of garlic. The fertilization and hatching rates ranged from 65.80 to 83.70% and 57.60 to 71.40%, respectively. The essential garlic oil levels showed linear effect on the fertilization rates (p<0.01) and hatching (p<0.05). Garlic oil did not influence the normal larvae (p<0.05). It is recommended to use 5 mg L-1 essential oil of garlic to promote better rates of fertilization and hatching of silver catfish eggs artificially incubated / A incubação artificial de ovos de peixes proporciona maiores quantidades de alevinos em relação às condições naturais. Porém, um dos procedimentos para que esta técnica reprodutiva obtenha bons resultados é a utilização de produtos antimicrobianos na água de incubação. Objetivou-se avaliar o efeito da utilização do óleo essencial de alho (Allium sativum) sobre as taxas de fertilidade, eclosão e normalidade das larvas de ovos de jundiá, Rhamdia quelen, incubados artificialmente. A pesquisa consistiu de dois experimentos (I e II) realizados no Instituto de Pesquisas em Aquicultura Ambiental (InPAA), Toledo, PR, no período de outubro a dezembro de 2014. Foi utilizado delineamento experimental inteiramente casualizado com quatro tratamentos e cinco repetições. Os tratamentos consistiram na introdução de óleo essencial de alho nas incubadoras, utilizando um sistema fechado de recirculação de água, com os níveis de 0; 5; 10 e 20 e 0; 1; 3 e 5 mg L-1 de óleo essencial de alho, respectivamente para o experimento I e II. A taxa de fertilização foi determinada após o fechamento do blastóporo, aproximadamente 10 horas pós-fertilização e a taxa de eclosão foi calculada com 24 h pós-fertilização, quando observado as larvas se desprendo do ovo. Utilizou-se do padrão morfológico de larvas para determinar a taxa de normalidade, com o auxílio de um microscópio estereoscópio. No experimento I a dosagem 5 mg L-1 promoveu maiores (p<0,05) taxas de fertilização e eclosão dos ovos. Nos níveis 10 e 20 mg L-1 houve morte de todos os embriões nas primeiras 10h após a fecundação. No experimento II a dosagem de 5 mg L-1 promoveu melhores taxas de fertilização (p<0,01) e eclosão (p<0,05) em relação às demais concentrações de óleo essencial de alho. As taxas de fertilização e eclosão variaram de 65,80 a 83,70% e 57,60 a 71,40%, respectivamente. Os níveis de óleo essencial de alho apresentaram efeito linear sobre as taxas de fertilização (p<0,01) e eclosão (p<0,05). O óleo de alho não influenciou na normalidade das larvas (p>0,05). Recomenda-se utilizar 5 mg L-1 de óleo essencial de alho para promover melhores taxas de fertilização e eclosão de ovos de jundiá incubados artificialmente

Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2017-07-24T16:03:54Z No. of bitstreams: 1 2009 - Helaine dos Reis Flor.pdf: 3447034 bytes, checksum: 3861cf7664eb46a21add49a26a4479c2 (MD5) / Made available in DSpace on 2017-07-24T16:03:54Z (GMT). No. of bitstreams: 1 2009 - Helaine dos Reis Flor.pdf: 3447034 bytes, checksum: 3861cf7664eb46a21add49a26a4479c2 (MD5) Previous issue date: 2009-09-01 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior, CAPES, Brasil. / Farfantepenaeus brasiliensis is a native species also known as the pink shrimp, and is one of the most explored fishing resources of the Brazilian coastline. This study aims to evaluate the reproductive performance of the F. brasiliensis raised in captivity submitted to different diets and sex ratios. Wild broodstock were captured in the Ba?a de Sepetiba, near to the Restinga da Marambaia and were kept for 107 days in maturation tanks at the Esta??o de Biologia Marinha da Universidade Federal Rural do Rio de Janeiro (EBM-UFRRJ). After ten days of acclimatization, the animals were randomly assigned to 18 polyethylene tanks, 450L volume, with constant aeration, continuous filtered seawater exchange, feeding trays and pieces of PVC pipes to serve as shelter. Each tank stored six animals. The experimental design was completely randomized with six treatments and three repetitions for each. Three diet feeding protocols were evaluated: A- 25% commercial diet /75% fresh food; B- 50% commercial diet 50% fresh food e C- 75% commercial diet /25% fresh food and two sex rations (male:female) 1:1 and 1:2 were evaluated. Females shrimp were unilaterally eyestalk ablated and marked with alternate cuts on the uropods for individual identification. The number of spawns, fecundity and hatching rate were used as the criteria for evaluation of reproductive performance. The 1M:2F sex ratio and the B feeding protocol had the best results regarding reproductive performance related to number of eggs/female and total egg production. Treatments that used the C diet presented the best hatching rates, despite of the low number of spawns. Throughout the experiment moulting occurred, however the spawning stopped between the 81st and the 90th day, probably due to physiological stress. At the end of the experiment, the females presented low survival rate in every treatment, possibly due to handling stress occurred during the gonadal maturation checks. Overall results of the present study indicated that it is possible to reproduce the F. brasiliensis in captivity, in small tanks, showing satisfactory reproductive performance. Nevertheless, it is necessary to re-evaluate the animal handling, in order to decrease the mortality and optimize the performance in captivity. / Farfantepenaeus brasiliensis ? uma esp?cie nativa conhecida como camar?o-rosa, e um dos recursos pesqueiros mais freq?entes e explorados na costa brasileira. Este trabalho teve como objetivo avaliar o desempenho reprodutivo de F. brasiliensis em cativeiro submetidos a diferentes dietas e propor??es sexuais. Os reprodutores selvagens foram capturados na Ba?a de Sepetiba, pr?ximo ? Restinga da Marambaia e mantidos durante 107 dias em tanques de matura??o na Esta??o de Biologia Marinha da Universidade Federal Rural do Rio de Janeiro (EBM-UFRRJ). Ap?s dez dias de aclimata??o, os animais foram distribu?dos aleatoriamente em 18 tanques de polietileno com volume ?til de 450L, com aera??o constante, fluxo cont?nuo de ?gua do mar filtrado, bandejas de alimenta??o e peda?os de canos de PVC para servir de abrigo para os animais. Em cada tanque foram colocados 6 animais. O delineamento experimental foi inteiramente casualizado com seis tratamentos e tr?s repeti??es cada. Foram avaliadas tr?s dietas alimentares: A-25% ra??o/75% alimento fresco; B-50% ra??o/50% alimento fresco e C-75% ra??o/25% alimento fresco e duas propor??es sexuais (macho:f?mea) de 1:1 e 1:2.Todas as f?meas foram abladas e marcadas com cortes alternados nos ur?podos para identifica??o individual. A avalia??o do desempenho reprodutivo foi realizada atrav?s do n?mero de desovas, fecundidade e taxa de eclos?o de cada tratamento. A propor??o sexual 1M:2F e a dieta B apresentaram os melhores resultados de desempenho reprodutivo em rela??o ao no de desovas e fecundidade. Os tratamentos que receberam a dieta C foram os que apresentaram melhor taxa de eclos?o, apesar do baixo n?mero de desovas. Ocorreram mudas durante todo per?odo experimental, por?m a ocorr?ncia das desovas cessou entre 81o e 90o dia de experimento, provavelmente por desgaste fisiol?gico. Ao final do experimento, as f?meas apresentaram alta mortalidade em todos os tratamentos, possivelmente devido ao estresse causado pelo manuseio di?rio para vistoria da matura??o das g?nadas. Os resultados obtidos no presente estudo constataram a possibilidade de F. brasiliensis reproduzir em cativeiro em tanques pequenos, apresentando desempenho reprodutivo satisfat?rio. Por?m ? necess?rio reavaliar o manejo, para diminuir a mortalidade e melhorar a efici?ncia de c?pula, para otimizar o desempenho em cativeiro.

Submitted by Aline Batista (alinehb.ufpel@gmail.com) on 2016-03-04T13:57:17Z No. of bitstreams: 2 Sombras Capturadas pela Experiência Noturna com o Desenho.pdf: 9011052 bytes, checksum: 031e8f369f0b356134d2edf6f9e6f15b (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2016-03-04T14:25:41Z (GMT) No. of bitstreams: 2 Sombras Capturadas pela Experiência Noturna com o Desenho.pdf: 9011052 bytes, checksum: 031e8f369f0b356134d2edf6f9e6f15b (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2016-03-04T14:28:18Z (GMT) No. of bitstreams: 2 Sombras Capturadas pela Experiência Noturna com o Desenho.pdf: 9011052 bytes, checksum: 031e8f369f0b356134d2edf6f9e6f15b (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2016-03-04T14:30:48Z (GMT). No. of bitstreams: 2 Sombras Capturadas pela Experiência Noturna com o Desenho.pdf: 9011052 bytes, checksum: 031e8f369f0b356134d2edf6f9e6f15b (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2014-04-04 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Os ensaios textuais que se seguem abordam os desenhos realizados a partir da observação das sombras percebidas em condições de iluminação precária, à noite. Desta forma, o trabalho artístico se articula na tensão entre o que se experiencia no encontro com o espaço noturno e as sombras, em consecutivas tentativas de capturar e registrar o que delas é visível. O texto enfatiza a relação do desenho com as condições de privação da visão, trazendo a discussão sobre a experiência de desenhar à noite. / This dissertation address the drawings made from observation of shadows perceived in conditions of poor light, mainly in the night. The artwork articulates the tension between experiences in the encounter with the shadows and attempts to capture and record which of them is visible. The text emphasizes the relationship of the drawing conditions of poor vision lighting, bringing the discussion about the experience of drawing in the night.

This thesis deals with important factors that affect the temporal organization of emergence and early survival of Baltic salmon (Salmo salar L.). The study population was obtained from the Norrfors hatchery (63°50'N,20°05'E), Umeälven (Ume river) in Northern Sweden. The main objectives of the thesis has been to study; a: the effect of female and egg characteristics on embryonic survival, b: the effect of egg size, temperature and photoperiod on the emergence pattern and c: the impact of early or late emergence on survival in relation to predation and limited territorial space. The main results are summarized as follows: (1) Fecundity and egg size increased with increasing weight of females. No effect of female size were found on egg colour. Longer impoundment and later stripping increase egg colour. Egg mortality was not correlated with egg colour. Stripping date was found to have the strongest effect on mortality. (2) Egg size had no effect on the timing of emergence but fry of different egg size emerged synchronously. Fry from large eggs left the gravel as heavier fry and with a larger proportion of yolk left compared to fry from small eggs. (3) The number of days and number of degree days from hatching to 50% emergence decreased exponentially with increasing temperature. Synchronization of emergence increased with increasing temperature. Fry emerged with more yolk at 12 °C compared to 6 °C. (4) Eggs kept in a LD 16:8 light regime hatched mainly during the light period, while eggs kept in constant darkness hatched continously over a 24 hour period. Alevins kept at different light regimes (light&gt;4h) from hatching until emergence left the gravel during the dark period. Daylength had no effect on the annual onset of emergence. (5) In a laboratory stream channel, predator presence at emergence increased mortality especially in early emerging fry. If the predator was introduced after completed emergence high mortality was noted among late emerging fry. The presence of fish predators and a limited territorial space for fry seemed to make early and late emergence hazardous and to favour a "peak" emergence. In the presence of a predator the fry changed their behaviour by reducing their swimming activity. / digitalisering@umu.se

A scaris is a genus of parasitic worms (helminths) found in the small intestine of various mammalian hosts, including Ascaris lumbricoides in humans, Parascaris equorum and P univalens in horses, Ascaris suum in pigs, Toxocara cati in cats and Toxocara canis in dogs. To date, Parascaris spp. are the only Ascaris worms that have developed resistance to anthelmintic drugs. The mechanisms of resistance in Parascaris spp are incompletely understood, partly due to the absence of robust in-vitro models. Further complicating in-vitro studies, Parascaris spp lack a free-living larval stage as their larva only hatch within the host. The aim of this study was to develop in-vitro methods for hatching, scoring the viability of Parascaris L3 larvae and exposing them to the anthelmintic drugs ivermectin, pyrantel, thiabendazole, and the herbal extract carvacrol. This study shows that mechanical Ascaris egg breaking using a homogenizer resulted in a hatching rate of 98%. Our viability scoring system could distinguish an ivermectin resistant larvae from an ivermectin susceptible larvae derived from different farms. This indicates that this method may have utility for the screening of larvae ivermectin resistance on the level of farm populations. Interestingly, a highly paralytic effect observed after carvacrol exposure. Carvacrol shows direct paralytic effects on Parascaris larvae in a dose-dependent manner, as higher concentrations were lethal to all exposed larvae. This result presents a potential future opportunity for carvacrol used in the treatment of Ascaris infections. To conclude our results, we have successfully developed an in-vitro model as well as a scoring system for the viability of Parascaris L3 stage larvae, which can be used for assaying the effect on larvae after drug exposure

MSCAGR (Animal Science) / Department of Animal Science / This study determined the effects of in vitro culture media (Ham’s F10 and TCM199) and assisted hatching techniques (laser or mechanical) on mice embryo survival following cryopreservation. Pure strain C57BL/6 (B6) female (50) and strain BALB /c (C) Male (25) mice were crossed to produce F1 generation of females which were injected for follicular growth and super ovulation at 6 weeks of age and from which embryos were produced 21 h later through in vivo fertilization. Embryos were randomly divided into Petri dishes with different culture media, and the development of embryos was assessed until the morula stage. At the morula stage, selected embryos were assisted to hatch using different techniques, and then cryopreserved in liquid nitrogen using the slow freezing method for a period of 1 week. After 1 week of cryopreservation, the embryos were thawed and cultured in the two different in vitro culture media for 72 hours. Thereafter, the numbers of embryos hatched or survived were recorded after 24 h, 48 h and 72 h. Data was analyzed using ANOVA in Minitab Software Version 16 (2010). Significant difference in embryo quality development was observed between in vitro culture media and stage of embryo development (P<0.05). In the TCM-199 in vitro culture medium, embryo quality development yielded 72, 69 and 69% from day 1 to day 3, while in Ham’s F10 embryo quality development yielded 68, 63 and 60% respectively. Relative to the control (18.1%) assisted hatching improved hatchability significantly (P<0.05) in the order laser (23.6%)>, mechanical (20.8%). There was significant (P<0.01) interaction between assisted hatching techniques and evaluation time, whereby laser assisted hatching was most successful at 48 h (42.0%) while mechanical assisted hatching was most successful at 72 h (36.8%). Cryopreservation reduced the embryo survival compared to fresh embryos. In conclusion laser was the best assisted hatching technique, while TCM-199 was the better medium for in vitro culture of embryo. / NRF

It is increasingly recognized that individuals of the same species differ from each other and influence and respond to their environment in unique ways. This thesis deals with size variation among individuals that not only are of the same species but also of similar age. Such variation may develop even when individuals are born in the same environment, i.e. within a cohort. I have studied the sources and consequences of variation within and among cohorts from egg through early ontogeny using young-of-the-year (YOY) perch (Perca fluviatilis) as study organism. In agreement with predictions based on model results only taking exploitative interactions among individuals into account, I found that the broader the initial size distributions were, the more did the degree of size variation among individuals decrease over time. Still, with initially small size variation among individuals, in several experiments also size divergence was observed. Furthermore, size variation among individuals increased more under high compared to at low densities. Increased size variation over time may be explained by size-dependent diet shifts allowing for initially larger individuals to make an early diet shift when the first resource becomes limiting. However, as size divergence also was observed in situations with only shared resources available, it can be concluded that diet shifts are not a prerequisite for size divergence in young animal cohorts. Hence, I also suggest that mechanisms not related to competition for limiting resources, such as genetic variation, stochasticity and behavioural traits must be taken into account, especially when initial size differences are small. The importance of considering size variation among individuals within cohorts was demonstrated in a study of winter mortality in YOY perch cohorts. A large individual size in autumn was shown to increase overwinter survival within cohorts. However, late summer growth rather than average body size reached in autumn explained variation in overwinter survival between cohorts. Higher accumulation to lipid reserves and accordingly lower mortality over winter was observed in years with high growth rates late in the season. In another study I showed that apparent patterns of density-dependent growth can emerge among larval fish, but rather than a result of density-dependent resource limitation this was due to variation in size-selective predation pressure. Individuals in the right end of the size distributions grew in to a high predation pressure from cannibalistic perch when cannibal density was high, coinciding with high larval perch densities. Finally, as substantial size variation among individuals can develop within cohorts, also intra-cohort cannibalism can occur. Using a physiologically structured population model it was shown that the development of size bimodality within cohorts as a result of intra-cohort cannibalism is critically dependent on long hatching periods, high victim densities and density-dependent feedbacks on shared resources. / Det faktum att individer som tillhör samma art skiljer sig från varandra och påverkar och påverkas av sin omgivande miljö på ett unikt sätt tillskrivs allt större betydelse inom ekologin. Den här avhandlingen handlar framför allt om storleksvariation mellan individer som förutom att tillhöra samma art dessutom tillhör samma årsklass. Sådan storleksvariation kan till och med utvecklas mellan individer som föds och växer upp i samma miljö (inom en kohort). Jag har studerat orsaker bakom och konsekvenser av variation inom och mellan kohorter. Som studieorganism har jag använt mig av årsyngel av abborre (Perca fluviatilis). I överensstämmelse med förutsägelser baserade på en modell som enbart tar hänsyn till konkurrens om en gemensam resurs visade det sig såväl i ett dammexperiment som i en naturlig sjö att ju bredare den initiala storleksfördelningen var desto mer minskade graden av variation i kroppsstorlek mellan individer över tid. Å andra sidan, när den initiala variationen var relativt liten observerades i flera oberoende experiment även storleksdivergens över tid mellan individer. Variationen i storlek ökade särskilt i miljöer med höga tätheter av konsumenter (abborrar). För att förstå de bakomliggande mekanismerna av sådana täthetseffekter måste man ta hänsyn till den återkoppling som sker mellan antalet konsumenter och mängden resurser. Ökad storleksvariation över tid skulle kunna förklaras med storleksberoende dietskiften som tillåter individer med en initial storleksfördel att genomgå ett tidigt dietskifte samtidigt som tillgången av den första resursen begränsar övriga individers tillväxt. Eftersom storleksdivergens även observerades i situationer där enbart en delad resurs var tillgänglig kan man dock dra slutsatsen att dietskiften inte är en förutsättning för storleksdivergens inom kohorter. Jag föreslår därför också att mekanismer som inte är relaterade till konkurrens om en begränsad resurs, såsom inneboende variation mellan individer och variation i beteendemönster bör beaktas för att förklara uppkomsten av storleksvariation, speciellt i de fall då den initiala variationen är liten. De resultat som presenteras visar på betydelsen av att ta hänsyn till storleksvariation mellan individer. Storlek efter den första tillväxtsäsongen var viktig för att förklara vilka individer inom en kohort av årsyngel som överlever sin första vinter. För att förklara variation i vinteröverlevnad mellan kohorter (mellan år och sjöar) var däremot hög tillväxt sent på säsongen (oberoende av medelstorlek på hösten) avgörande. Högre ackumulering av fettreserver och lägre mortalitet inom kohorter av årsyngel under vintern observerades under år med hög tillväxt under den senare delen av tillväxtsäsongen. I en annan studie visade jag att mönster som tyder på täthetsberoende tillväxt kan uppkomma hos fiskyngel men att detta fenomen snarare än täthetsberoende resursbegränsning förklaras av variation i storleksberoende predationstryck. De större individerna inom kohorterna växte in i ett högt predationstryck från kannibalistiska abborrar när tätheten av kannibaler var hög, något som samkorrelerade med höga tätheter av yngel. Slutligen, då en hög grad av storleksvariation mellan individer kan utvecklas inom kohorter är även kannibalism mellan individer inom en kohort möjligt. Genom att använda mig av en så kallad fysiologiskt strukturerad populationsmodell kunde jag visa att divergerande tillväxtkurvor mellan kannibaler och deras byten (vilket resulterar i storleksbimodalitet) som ett resultat av kannibalism inom kohorter är beroende av den tid det tar för ynglen att kläcka ut, antalet bytesfiskar per kannibal samt den återkoppling som finns mellan konsumenterna och deras gemensamma resurs (djurplankton).

Captive husbandry programs in zoos have documented nesting behavior and have successfully hatched Manouria emys emys, but data on sex determining mechanisms and sex ratios are absent. A total of 30 M. e. emys eggs were artificially incubated at five different temperatures in constant humidity. Mean incubator temperatures were 24.99°C, 25.06°C, 27.18°C, 28.00°C, and 30.79°C. Incubation duration ranged from 60 days to 92 days, and hatching success was 50%. Sex determined by histology and laparoscopy resulted in male differentiation at low temperatures (24.99°C, 27.18°C) and female differentiation at high temperatures (30.79°C). Pivotal temperature was estimated to be 29.29°C. The following investigation into temperature-dependent sex determination (TSD), including its presence or absence, pattern, and pivotal temperature, has implications for studies of adaptive significance of reproductive behaviors and of chelonian phylogenetic history. Additionally, the proposed study can provide foundations for conservation management decisions, and for captive breeding programs.

This study investigated factors associated with two mortality events: avian botulism in waterfowl and mortality associated with hatching asynchrony in prefledgling Franklins gulls (Larus pipixcan). The initial focus of my research was on the spatiotemporal relationship between mortality of Franklins gulls and the onset of botulism outbreaks in waterfowl, and the suitability of gull carcasses for proliferation and toxigenesis of Clostridium botulinum. From 1999 to 2001, dead hatch-year Franklins gulls were by far the most abundant carcasses, and the only source of toxin-laden maggots found on transects prior to the occurrence of avian botulism in waterfowl. Nest density was a significant predictor of hatch-year gull carcass density. High density of toxic material from gull carcasses prior to the onset of botulism in waterfowl coincided with high densities of susceptible birds; hence, mortality of Franklins gulls has the potential to be a major initiating factor for botulism outbreaks at Eyebrow Lake, Saskatchewan. The causes of gull mortality were conditions or diseases associated with starvation, stress, or immunosuppression, and most mortality occurred in third-hatched chicks. To separate effects of laying order from effects of hatching asynchrony on prefledgling survival, a cross-fostering experiment was conducted to create clutches containing asynchronously hatching eggs of the same laying order, and of similar egg mass, egg volume, and female quality. Hatching order, independent of laying order, significantly affected survival to fledging, whereas laying order had no observable effect, indicating that intraclutch variation in egg quality does not predetermine the fate of prefledglings, and may be less important than hatching asynchrony for survival of prefledgling Franklins gulls. Relationships among hatching asynchrony, laying order, mass, corticosterone, immune function, growth, and survival at two stages of development were complex. Hatching asynchrony significantly affected early and late prefledgling survival, and was directly or indirectly associated with mass, corticosterone level, and cell-mediated immune responses at early and later stages of development. Both hatching asynchrony and mass appeared to play key roles in mediating life history trade-offs among cell-mediated immune function, growth, and survival. In contrast to cell-mediated immune responses, primary humoral immune response was not directly affected by hatching order or mass, nor was it associated with survival to fledging. Rather, it was associated with laying order, neonatal testosterone, corticosterone at 2 weeks, growth of leg length, and clutch initiation date, illustrating the importance of examining more than one branch of the immune system in studies of life history trade-offs. This study is a step toward using a multipronged and multidisciplinary approach to demonstrate interactions and trade-offs among life history traits, the physiological mechanisms that produce these relationships, and how these relationships may change depending on stage of development.