A central question in life history theory is, what combination of traits and behaviors will lead to the highest reproductive success throughout a lifetime. The trade-off between current and future reproduction is central to the lifetime reproductive success of an organism. If there is a cost to reproduction, then allocation of energy to current reproduction will come at a cost to future reproduction. We expect young individuals to favor future reproduction over current reproduction and that balance shifts to current reproduction as they age (i.e. terminal investment hypothesis). However, how this transition from an emphasis on future reproduction to emphasis on current reproduction changes throughout a lifetime should depend on environmental factors like mortality and resource availability. We test for the generality of terminal investment across three species of poecilliid fishes in a range of environments. We found evidence of terminal investment in all three species in both high and low mortality environments and high and low resource availability environments. In general, high mortality or high resource availability tended to result in a decreased slope of the relationship between reproductive allocation and body size. Terminal investment appears to be general, even though there was an effect of high mortality and resource availability, it was not sufficient to completely preclude terminal investment.

Temperature variation experienced across a latitudinal range is tied to changes in lifespan and life history across multiple taxa. Two patterns of adaptation to latitudinal temperature variation have been documented – counter-gradient (or co-gradient) variation, and local adaptation. To determine how natural selection has shaped life history variation in a burying beetle, Nicrophorus orbicollis, we quantified lifetime patterns of reproduction in two populations that represent the geographic and temperature extremes occupied by the species. Lifetime reproduction was quantified at two temperatures that represented conditions typical for each population. Burying beetles from different extremes of their geographic range show considerable variation in lifetime survival and reproduction at different temperatures. Patterns are generally consistent with the local adaptation hypothesis. However, at the higher temperature both populations have lower and equal numbers of offspring over a lifetime. High temperatures may create a constraint on offspring production because of the increased cost of maintaining the food source against bacterial decomposition. This temperature constraint on reproductive success may partially explain the absence of burying beetles from tropical environments, and may predict reductions in latitudinal range as global climate change proceeds.

Syftet med denna uppsats är att undersöka hur den svenska gymnasieskolans förändringar sedan början av 1970-talet har påverkat en enskild lärares yrkesliv. Frågeställningarna lyder som följer; Vilka förändringar har skett i den svenska gymnasieskolan sedan början av 1970-talet? Hur har dessa förändringar påverkat en enskild lärares yrkesliv? För att uppnå mitt syfte och besvara mina frågeställningar har jag använt mig av en muntlig källa och av flera skriftliga källor. Mitt teorikapitel innefattar tre avsnitt; undersökningen Nära gränsen, gjord av Arbetslivsinstitutet, samt begreppen oral history och livshistoria. Förändringarna i den svenska gymnasieskolan sedan 1970-talet fungerar som en bakgrundsteckning. Kapitlet Slutsatser består i mångt och mycket av en diskussion kring vad som skapar och påverkar en lärares arbete. Tydligt är att samspelet mellan myndigheter och lärare samt mellan lärare och elever är av stor betydelse. / The purpose of this essay is to examine how the changes in the Swedish gymnasium since the the beginning of the 1970-thies have affected the professional life of one common teacher. The questions at issue are; Which changes have occured in the Swedish gymnaisum since the beginning of the 1970-thies? How has these changes affected the professional life of one common teacher? I have used both an oral source and and written sources in order to attain my pourpouse and answer my questions. The chapter concerning theories regarding the subject of this essay contains an investigation performed by the Arbetslivsinstitut, Nära gränssen, and concepts such as oral history and life history. The Changes in the Swedish gymnasium serves as background material. The chapter named Conclusions contains a discussion concerning what makes and influences the work of a teacher. It is obvious that the interaction between the authorothies and theachers and between teacher and students is of great significance.

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付記する学位プログラム名: 霊長類学・ワイルドライフサイエンス・リーディング大学院 / 京都大学 / 新制・課程博士 / 博士(理学) / 甲第23746号 / 理博第4836号 / 新制||理||1691(附属図書館) / 京都大学大学院理学研究科生物科学専攻 / (主査)教授 平田 聡, 教授 伊谷 原一, 教授 村山 美穂 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

Oxidative stress from high-dose ionizing radiation can contribute to accumulating cellular damage, affecting various fitness related traits. However, studies on low-dose ionizing radiation (LDIR) have shown hormetic effects on growth, longevity, and immunity. Comprehensive lifetime studies assessing LDIR effects and studies investigating LDIR immune stimulation in insects are limited. We utilized 137Cs gamma radiation with a dose rate of 0.25 Gy/min. We examined the impacts of early-life exposure (doses: 0, 0.2, 0.5, 1, 2, 4, 7, and 10 Gy) on life history and immunity in Acheta domesticus. Moderate doses (above 4 Gy) increased mean longevity but decreased growth rate, adult body mass and innate immunity. We also performed a time course study in male A. domesticus to assess the acute effects of radiation (doses: 0, 0.2, 0.5, 0.75, 1, 5, and 15 Gy) on innate immunity and redox status. LDIR (below 1 Gy) generally achieved immune stimulation and improved the encapsulation response but effects were time dependent. Benefits could extend to improved immune responses and protection against infection. Our results provide evidence of immune stimulation with LDIR in insects but with potential trade- offs with life history traits when assessing early-life exposure. With increasing concern of radiation exposure in the environment, more comprehensive studies utilizing a multi- discipline approach will help to elucidate the full mechanism of hormesis. / Thesis / Master of Science (MSc) / High-dose ionizing radiation can have inhibitory effects on cellular systems while low doses can have lasting stimulatory effects. The latter phenomenon, known as hormesis, can act on growth, longevity, and immunity. We investigated the effects of early life gamma radiation exposure on life history traits and measures of innate immunity in the cricket (Acheta domesticus). We observed trade-offs between survival, growth, and immunity. We also tested late life radiation exposure to assess potential hormetic effects on innate immunity and redox status. Our results show immune stimulation with low doses but effects are complex and dependent on dose, type of immunity measured, and time of assessment.

The world's islands are of singular importance from a conservation perspective because they hold a disproportionate share of global biodiversity. However, island ecosystems are fragile, and the introduction of invasive species poses an especially grave threat to their species. My research took place on the island of Guam, which has been particularly hard hit by invasive species in recent history. The introduction of the invasive Brown Treesnake (BTS; Boiga irregularis) to Guam in the mid-20th century caused the extinction of the vast majority of its avifauna. Of the remaining bird species, the native Såli (Aplonis opaca) is a forest starling now limited to breeding and roosting in certain urbanized areas on the island. Previous research has shown that although Såli adults appear to have high survival, their fledglings are highly vulnerable to predators. My research focused on refining our understanding of how BTS are impacting Såli ecology and survival, and how BTS management can benefit Såli conservation. In my first chapter, I conducted the first field study to investigate the influence of both prey and predator sizes on the frequency of ingestion success by snakes. I found that nearly half of ingestion attempts by BTS on fledgling Såli were unsuccessful, and that BTS routinely pushed the upper limits of their capacity to swallow prey. These results suggest that relatively small BTS pose a greater predation risk to birds than previously recognized, and broaden the size range of BTS that should be targeted in management efforts for avian conservation. In my second chapter, I investigated a potential life-history trade-off for Såli between the proximity of nest sites to foraging areas and the risk of fledgling predation by BTS. I found that Såli nesting closer to the forest make more yearly nesting attempts, but that fledgling survival was higher the farther their nest site was from the forest. Såli therefore balance potential fecundity with predation risk to fledglings in their selection of nest sites. In my third chapter, I examined the survival response of fledgling Såli to the suppression of BTS. I found that snake control did not lead to a change in fledgling survival from the pre-treatment baseline or in comparison to areas where snakes were not controlled, and that there was no shift from snake predation to other causes of mortality. Changes to the strategies or tools employed will therefore be required in order for future BTS control efforts within similar habitats to effectively improve avian survival. This body of work demonstrates that BTS are affecting Såli in unexpected ways, and offers new guidance on how to manage damaging invasive species for native species conservation. / Doctor of Philosophy / Islands are of high value important for conservation because they hold a more than their share of the world's animal and plant species. However, island ecosystems are fragile, and the introduction of damaging exotic species is especially threatening to species that live there. My research took place on the island of Guam, which has been particularly hard hit by damaging non-native species in recent history. The introduction of the Brown Treesnake (BTS; Boiga irregularis) to Guam in the mid-20th century caused the extinction of the vast majority of its bird species. Of the remaining bird species, the native Såli (Aplonis opaca) is now limited to breeding and roosting in certain developed areas on the island. Previous research has shown that although Såli adults appear to have high survival, their fledglings (young birds that recently left the nest) are highly vulnerable to predators. My research focused on refining our understanding of how BTS are impacting Såli life cycles, and how BTS management can benefit Såli conservation. In my first chapter, I conducted the first field study to investigate the influence of both prey and predator sizes on the capacity for snakes to swallow their prey. I found that nearly half of attempts by BTS to swallow fledgling Såli were unsuccessful, and that BTS routinely pushed the upper limits of their capacity to swallow prey. These results suggest that relatively small BTS pose a greater predation risk to birds than previously recognized, and broaden the size range of BTS that should be targeted in management efforts for avian conservation. In my second chapter, I investigated a potential life-history trade-off for Såli between how close their nest sites are to foraging areas and the risk of fledglings being killed by BTS. I found that Såli nesting closer to the forest make more nesting attempts per year, but that fledgling survival was higher the farther their nest site was from the forest. Såli therefore balance the potential number of young they can raise with the predation risk to those same young in their choice of nest sites. In my third chapter, I examined whether the suppression of BTS led to a change in the survival of fledgling Såli. I found that snake control did not lead to a change in fledgling survival from the period before the treatment or in comparison to areas where snakes were not controlled, and that there was no shift from snake predation to other causes of death. Changes to the strategies or tools employed will therefore be required in order for future BTS control efforts within similar habitats to effectively improve avian survival. This body of work demonstrates that BTS are affecting Såli in unexpected ways, and offers new guidance on how to manage damaging invasive species for native species conservation.