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.

A central goal of life history theory is to understand the selective factors that generate the diversity of reproductive patterns observed in nature. Within lifetime changes in reproductive investment will determine an organism's fitness; however, this area of life history theory has received less attention than comparisons among population that characterize life history traits as a single population mean. Reproductive allocation can be affected by multiple cues; the integration of these cues across an organism's lifetime generates the diversity in life history strategies observed in nature. Life history studies should examine the interacting effects of multiple cues on life history strategies to generate better predictions and generalizations of age-related changes in reproductive investment. An individual's life history strategy is inherently multivariate consisting of a coordinated suite of life history traits that, when combined across the organism's lifetime, determines its fitness. Life history strategies can therefore be described as a trajectory through multivariate space defined by life history traits. Here I describe life history trajectory analysis, a multivariate analytical approach for quantifying and comparing phenotypic change in life history strategies; this methodology is adapted from an analytical framework originally described for studies of morphological evolution. Life history trajectories have attributes (magnitude, direction, and shape) that can be quantified and statistically compared among taxa to determine if life history patterns are predictable. Using the life history trajectory analysis, I demonstrate the effect of prior experience on reproductive allocation in the burying beetle Nicrophorus orbicollis. The effect of prior experience resulted in a terminal investment or accentuated response to age-based cues, or resulted in a conservative investment strategy or reproductive restraint. In the livebearing fish Gambusia affinis, females adjust the level of reproductive investment to current reproduction based on age- or environment-based cues. Age-0 females decreased the level of reproductive investment to current reproduction in late summer prior to the onset of fall and winter months. Old females, on the other hand, increased the level of reproductive investment as the summer progressed. The reproductive restraint and terminal investment patterns exhibited by age-0 and age-1 females, respectively, were consistent with the predictions from the cost of reproduction hypothesis. These studies demonstrate how the life history trajectory analysis provides an analytical tool to test predictions of life history theory. Additionally, I provide evidence that organisms use multiple cues to determine the level of reproductive investment and that the strength of the effect of each cue will depend on the age of an individual.

Tesi realitzada al Instituto Pirenaico de Ecología (CSIC) / Widespread species have traditionally received much less attention than rare and endemic ones. However, they are crucial in macroecological patterns and in ecosystem structure and functioning. Thus, understanding the characteristics that allow widespread organisms to extend over large areas has a high interest from both theoretical and applied perspectives. One of the most frequent hypotheses to explain the success of widespread plants is that they show much wider ecological niches, and thus a high life-history and demographic variability. However, studies are often very specific and carried out over small spatio-temporal scales, which hinders a general understanding of intraspecific variation in widespread taxa. In this thesis, we span a large spatio-temporal scale and a large environmental gradient to analyze the magnitude and the possible causes of natural variation in the in the range centre and the northern periphery of the widespread herb Plantago coronopus. More precisely, we analyze variability in population dynamics, life-history traits, and genetic diversity in up to 22 populations in Europe and North Africa. We aim to explore the relation of such variability with the position of populations within the species’ range, since peripheral populations are traditionally expected to show a lower and more variable performance with respect to central populations. Additionally, we aim to analyze the effects of the most relevant environmental factors in population and individual performance at different spatial scales. In the first chapter, we found higher values in central populations in some vital rates, such as fecundity and growth, but recruitment and density were higher in northern peripheral populations, and there were no clear differences between regions in temporal variability of vital rates. Differences in population performance across the species’ range seemed to be correlated with local precipitation and intraspecific competition. In the second chapter, differences in mean values and variability of vital rates between central and peripheral areas led to no differences in stochastic population growth rates. In addition, recruitment was the most influential vital rate for population growth rates at different spatial scales, and we found the same pattern of differentiation in population dynamics in response to environmental conditions within central and peripheral regions. In the third chapter, we reported high variation among populations in seed traits along a steep environmental stress gradient. Moreover, patterns in seed production were opposite at the fruit and the individual scale, as a strategy of populations to maximize fitness in each set of local conditions. Finally, in the fourth chapter, we found no relationship within populations between phenotypic variability and genetic diversity. Phenotypic variation was mainly shaped by precipitation variability, suggesting adaptive variation, whereas genetic diversity was correlated with the central vs. peripheral position, probably in close relation with some random demographic processes experienced by populations in the past. Despite genetic diversity was higher in central populations, our results contradicted classical hypotheses predicting a lower demographic performance towards species’ range edges. In fact, environmental conditions seemed to have a higher influence on plant performance than the position of populations within the species’ range, which calls for the necessity of distinguishing between geographical periphery and ecological marginality in demographic studies. Overall, our study highlights the versatility of P. coronopus at different spatial scales in response to varying environmental conditions, complementing similar findings of previous research on the same taxon at smaller spatial scales. Such life-history variability seems to be a key factor for widespread plants to extend over large and heterogeneous ranges. / Las especies de amplia distribución han recibido tradicionalmente poca atención, a pesar de su importancia para la estructura y el funcionamiento de los ecosistemas. En esta tesis, se analiza la variabilidad demográfica, de historia vital y genética en una planta de amplia distribución en Europa y el norte de África (Plantago coronopus), en un total de 22 poblaciones a lo largo de gran parte del rango latitudinal de la especie (centro y periferia norte). Se pretende analizar la magnitud y las causas de esta variabilidad intraespecífica en relación con la posición de las poblaciones dentro del rango y con los principales factores medioambientales. Las poblaciones periféricas mostraron una menor diversidad genética, pero no mostraron en general un peor o más variable comportamiento demográfico en cuanto a densidad o tasa de crecimiento poblacional, contradiciendo así las hipótesis clásicas centro-periferia. Se encontró un mismo patrón de diferenciación demográfica dentro de las regiones tanto central como periférica, en relación con la variación en el régimen de precipitaciones. La tasa de reclutamiento de nuevos individuos fue el proceso del ciclo vital con mayor importancia para el funcionamiento de las poblaciones. Se encontró también una gran variación entre poblaciones en las características de las semillas (número, tamaño, mucílago y proporción de dos tipos de semilla dimórficos) en relación con el gradiente de estrés ambiental. Finalmente, la variación fenotípica dentro de las poblaciones se relacionó con la variabilidad ambiental, mientras que la diversidad genética se correlacionó con la posición central vs. periférica de las poblaciones y posiblemente con la historia demográfica de la especie. Globalmente, este estudio muestra la importancia de distinguir entre periferia geográfica y marginalidad ecológica, y sugiere que el éxito de las plantas de amplia distribución reside en una gran variabilidad demográfica y de historia vital a diferentes escalas espaciales.