Dissertations / Theses on the topic 'Sex allocation'

要旨pdfファイル:タイトル「オオヨシキリにおける性分配」
Kyoto University (京都大学)
0048
新制・論文博士
博士(理学)
乙第10195号
論理博第1366号
新制||理||1132(附属図書館)
UT51-99-S312
(主査)教授 山岸 哲, 教授 米井 脩治, 助教授 今福 道夫
学位規則第4条第2項該当

The study of sex allocation is one of the most successful areas in evolutionary biology: its theoretical predictions have been supported by experimental, observational and comparative approaches. Here, I develop sex allocation theory as follows: (1) I use fertility insurance theory to predict the sex ratio strategy of the malaria parasite, in response to human medical interventions that increase mortality and decrease fertility of the parasite’s various sexual stages; (2) Haplodiploidy has been suggested as a driver of the evolution of eusociality, as under this genetic system a female may be more related to her sister than to her own offspring. I examine a model considering queen versus worker control over the sex ratio of the colony and show that haplodiploidy alone does not explain the evolution of helping; (3) I follow up this study of the haplodiploidy hypothesis by examining the idea that split-sex ratios may favour the evolution of eusociality in haplodiploid species. I study the two mechanisms of split sex ratios, that are found in natural populations and may have been important in the transition to eusociality: queen virginity and queen replacement. I focus on the impact of worker reproduction by considering the effect of woker producing a fraction of the colony offspring and by considering variation in the workers’ offspring sex ratio. My analysis shows that worker reproduction does not promote the evolution of helping in haplodiploid species; (4) I examine the evolution and function of a sterile soldier caste in parasitoid wasps from the genus Encyrtidae. Two main functions have been hypothesized for the emergence of soldiers: spiteful mediation of a sex ratio conflict in mixed-sex broods, and altruistic protection and 7 facilitation of the development of relatives. I develop a model considering variation in the oviposition behaviour of females, that may produce single-sex or mixed-sex broods. I show that, in accordance with previous theory, females are expected to produce more soldiers than males, under the sex ratio conflict hypothesis. I also show that one of the consequences of this costly conflict is that females are favoured to produce single-sex broods over mixed-sex broods.

Fitness components of small and large males (emerging respectively from small and large hosts) of Trichogramma evanescens Westwood (Hymenoptera: Trichogrammatidae) were compared in laboratory experiments. These components were the longevity, courtship, mate competition, and daily and lifetime fertilization. Small males were less fit than large males: they had a reduced longevity, took longer to induce female mating behavior, rarely succeeded in mating females when in competition with large males and had lower fertilization capacity; female fertilized by small males oviposited in the first two days of their life only one third of the progeny of daughters mated by large males. The impact of males fitness on optimal sex allocation by females parasitoids was evaluated by measuring the primary and tertiary sex ratios (proportion of males in the progeny) produced by a female T. evanescens when ovipositing in small and large hosts (low and high quality patches). Females of T. evanescens, an arrhenotokous species, have control on the sex ratio of their offspring by regulation of the sperm's access to the egg. Certain combinations of male and female eggs deposited in a host patch result in greater fitness than others. As predicted, females produced a significantly higher proportion of males on the low quality patches. T. evanescens females adjusted the sex ratio allocated to a patch of homogeneous quality and under complete local mate competition to the expected fitness of their sons, as smaller males have a lower fitness and are expected to have low fertilization capacity and therefore fertilize less females. To optimize her fitness gain (the capacity of the individual to transmit its genes), the sex ratio is increased in order to have all daughters mated.

Rising archipelagos provide unique settings for the study of the temporal and spatial dynamics of their biota. This offers the possibility to study the ecology and genetics of early successional processes; both between islands that differ in age and within islands when already established organisms have to keep pace with the changing environment. I have worked in the Skeppsvik Archipelago housing about 100 islands that due to land uplift vary in age, thus representing various stages of primary succession. I have utilized a naturally created metapopulation of Silene dioica, which in this archipelago is a dominant plant of the deciduous border, offering the possibility to study subpopulations on islands of different ages and in different phases of primary succession. Many plant species exist as metapopulations, which consists of many local populations which may differ in size and degree of connectivity. Metapopulations are further characterized by recurrent colorizations and extinctions of local populations, meaning that a species continually must disperse and relocate to allow for persistence in this system. For a dioecious plant species, gene flow is in the shape of seeds and pollen and to allow for the persistence of populations, it is necessary that levels of seed dispersal and pollen gene flow are enough to ensure both colonisation, establishment and subsequent population growth. Levels of seed dispersal and pollen gene flow is in turn influenced by how the two sexes partition resources between reproduction, growth and survival. In paper I, I combined a field survey, a common garden experiment and a nine-year demographic study to assess the demographic consequences of sex-specific resource allocation and to investigate if differential costs of reproduction may be a driver in the evolution of sexual dimorphism in dioecious Silene dioica. Significant somatic intersexual dimorphism was found with females being the larger sex, both in terms of above – and belowground biomass. Furthermore, the reproductive effort of females exceeds that of males across a growing season which largely confirms what has been observed earlier in dioecious, herbaceous plant species. According to the cost of reproduction hypothesis, high reproductive investment should result in trade-offs with somatic and/or life-history traits. Somatic trade-offs were not observed, and instead I found strong, positive associations between reproductive investment and vegetative growth in both males and females. Compensation mechanisms were found in both sexes although females are generally more efficient at compensating their reproductive costs. At the end of a flowering season, after having paid the current costs of reproduction, females are better than males at provisioning perennial roots and rosettes potentially influencing the ability to set future flower buds and winter survival. Trade-offs were found between current and future reproduction and survival, but this is condition dependent and compensation through frequency of flowering plays an important role. The cost of reproduction hypothesis appears to play some role in driving the somatic and demographic sexual dimorphisms observed in this system but sexual selection acting on males will be a fruitful avenue for future research. In paper II, I investigated the population genetic consequences of metapopulation dynamics in Silene dioica. The occurrence of islands in different phases of primary succession together with successional gradients across islands, makes it possible to investigate the genetic dynamics occurring in an age-structured metapopulation across several hierarchical levels. Genetic diversity and differentiation were estimated in eight young, recently colonised populations and in ten populations of an intermediate successional stage. Young populations were less genetically diverse compared to older populations, indicating that bottlenecks, created by small founding groups derived from a limited number of source populations, reduce the genetic diversity within newly founded populations. The observation of strong genetic structure both between islands and between patches with islands, indicates that gene flow is restricted across several spatial levels in this system. However, the lack of statistically significant differences in genetic differentiation between young and intermediate populations, indicates that levels of gene flow may not be high enough to reduce the genetic differentiation that arise from the initial founder event. The patterns of sexual dimorphism and the roles of males and females in Silene dioica have evolved to allow persistence in an ecological and population context of this species. The nature of this habitat, where islands rise up from the sea creating new environments for colonisation while at the same time, autogenic primary succession processes eventually leads to extinction, means that S. dioica continuously must relocate within successional phases for its persistence. The obvious success of this dioecious plant is apparent as it is one of the few dominant species in the deciduous border. This suggests that levels of seed dispersal and gene flow are sufficient enough to allow for establishment and persistence of island populations and that the sexual dimorphisms that have evolved in this metapopulation system act to increase levels of gene flow. The "live hard – die young" strategy, with extensive flowering bouts, which we find in the males may have evolved as a way of maintaining sufficient levels of genetic diversity in the metapopulation but will only be a possible strategy if there are continuous opportunities for re-establishments. Thus, the continuous land uplift that is occurring in the northern part of the Gulf of Bothnia may very well be a prerequisite for the long-term persistence of this dioecious, perennial plant species.
Landhöjningsprocesser i skärgårdsmiljöer skapar nya habitat som gör det möjligt att studera naturliga populationer i ett rumsligt och tidsmässigt sammanhang. Detta möjliggör studier av ekologi och genetik i tidiga successionsprocesser, både mellan öar som skiljer sig åt åldersmässigt och inom öar, där redan etablerade organismer måste anpassa sig till en föränderlig miljö. Jag har utfört studier i Skeppsviks skärgård som rymmer cirka 100 öar. På grund av landhöjningen så varierar dessa öar i ålder och de representerar således olika stadier i primärsuccession. Jag har använt mig av en naturlig Silene dioica metapopulation lokaliserad i Skeppsviks skärgård. Många växtarter existerar i metapopulationer, vilket består av ett antal lokala populationer som kan skilja sig åt i storlek och grad av anknytning. Metapopulationer kännetecknas även av återkommande koloniseringar och utrotningar av lokala populationer, vilket innebär att en art kontinuerligt måste sprida sig för att garantera sin fortlevnad i detta system. Genflöde inom dioika växtarter är i form av pollen och frön, och för att populationer skall kunna överleva så är det nödvändigt att nivåerna av fröspridning och pollen-genflöde är tillräckliga för att säkerhetsställa både kolonisering, etablering och efterföljande populationstillväxt. Nivåer av fröspridning och pollen-genflöde påverkas i sin tur av hur de två könen partitionerar resurser mellan reproduktion, tillväxt och överlevnad. I den första studien har jag kombinerat en fältundersökning, ett frilandsexperiment och en nioårig demografisk studie för att undersöka de demografiska konsekvenserna av könsspecifik resursallokering och för att utreda om könsspecifika skillnader i reproduktiv kostnad kan vara en drivkraft för evolutionen av sexuell dimorfism hos den dioika växten Silene dioica. Jag upptäckte signifikant somatisk intersexuell dimorfism där honor hade betydligt mer ovanjordisk och underjordisk biomassa jämfört med hanar. Över en växtsäsong så investerar honorna mer resurser i reproduktion, vilket i stor utsträckning bekräftar vad som tidigare har observerats i örtartade, dioika växter. Enligt hypotesen för reproduktiv kostnad så bör en hög investering i reproduktion leda till trade-offs med somatiska egenskaper, t.ex. tillväxt. Jag observerade inga somatiska trade-offs och istället fann jag positiva associationer mellan reproduktion och tillväxt hos både honor och hanar. Båda könen verkar ha utvecklat kompensationsmekanismer, även om honorna generellt är mer effektiva i hur de kompenserar för sina reproduktiva kostnader. Vid slutet av en växtsäsong, efter att ha betalat för de nuvarande reproduktiva investeringarna, så är honor bättre än hanar på att allokera resurser till fleråriga strukturer, såsom bladrosetter och rötter. Detta kan potentiellt påverka hur de anlägger sina knoppanlag för nästkommande år och hur väl de överlever vintern. Trade-offs hittades mellan nuvarande reproduktion och framtida reproduktionsmöjligheter och överlevnad men detta var habitat-specifikt och kompensation med hjälp av hur ofta en växt blommar under sin livstid spelar en viktig roll. Hypotesen för reproduktiv kostnad verkar vara en del av förklaringen till den somatiska och demografiska könsdimorfism som observerats i detta system men sexuell selektion, som verkar på hanar, kan vara ett möjligt område för framtida studier. I den andra studien undersökte jag populationsgenetiska konsekvenser av metapopulationsdynamik i Silene dioica. Förekomsten av öar i olika faser av primär succession tillsammans med olika grader av succession inom öar gör det möjligt att undersöka den genetiska dynamiken som uppträder i en åldersstrukturerad metapopulation över flera hierarkiska nivåer. Genetisk mångfald och differentiering uppskattades i åtta unga, nyligen koloniserade populationer och i tio populationer av ett intermediärt successionsstadium. Unga populationer hade lägre genetisk diversitet jämfört med äldre populationer, vilket indikerar att genetiska flaskhalsar, skapade av fåtal antal koloniserande individer, s.k. founders, som härrör från ett begränsat antal källpopulationer, minskar den genetiska diversiteten inom nybildade populationer. Observationen av stark genetisk strukturering, mellan och inom öar, indikerar att genflödet är begränsat över flera rumsliga nivåer i detta system. Bristen på statistiskt signifikanta skillnader i genetisk differentiering mellan unga och intermediära populationer indikerar emellertid att nivåer av genflöde kanske inte är tillräckligt höga för att minska den genetiska differentieringen som uppstår från den ursprungliga founder-händelsen. Mönstren av sexuell dimorfism och hanarnas och honornas roll har utvecklats för att möjliggöra fortlevnad i ett ekologisk och populationsmässigt sammanhang hos Silene dioica. I denna livsmiljö, där öar stiger upp ur havet och skapar nya miljöer för kolonisering samtidigt som autogena primära successionsprocesser leder till utrotning, måste S. dioica kontinuerligt sprida sig mellan olika successionsfaser för att överleva. Den uppenbara framgången för den här dioika växten är uppenbar eftersom den är en av de få dominerande arterna i lövkanten. Detta tyder på att nivåer av fröspridning och genflöde är tillräckliga för att möjliggöra etablering och beständighet av ö-populationer och att de sexuella dimorfismer som har utvecklats i detta metapopulationssystem verkar för att öka nivåerna av genflöde. "Lev hårt – dö ung" -strategin med omfattande blomningar som vi finner hos hanarna kan ha utvecklats som ett sätt att upprätthålla tillräckliga nivåer av genetisk diversitet i metapopulationen men den kommer endast att vara en möjlig strategi om det finns kontinuerliga möjligheter för re-etableringar. Således kan den kontinuerliga landupphöjningen som förekommer i norra delen av Bottniska viken mycket väl vara en förutsättning för den långsiktiga beständigheten av denna dioika, fleråriga växtart.

Felaktigt angivet "Dissertation for PhD" i kolofon.

Haplodiploid Hymenoptera females control the sex of their progeny, and their sex allocation is influenced by several factors. The impact of intra- and interspecific competition and of inbreeding and outbreeding on sex allocation has been studied in some species of the egg parasitoid Trichogramma. The pre-mating dispersion has also been studied. Impact of competition on sex allocation was observed for Trichogramma minutum Riley and Trichogramma pintoi Voegele. These species were chosen because of the ease with which than can be distinguish. Results show that females of both species lay more males under intraspecific competition than alone, following the Local Mate Competition theory, while only T. pintoi modifies its sex ratio under interspecific competition. Multiparasitism and natural habitat could explain this shift in the sex ratio. Trichogramma minutum, T. pintoi and Trichogramma evanescens Westwood pre-mating dispersion show that most matings occur at the emergence site. However, the three species have a potential for off-patch mating, allowing genetic exchange between sub-populations. These three species were chosen because they are classified in different groups in the genus. Finally, T. evanescens did not modify its sex ratio following inbreeding or outbreeding. The incapacity to discriminate between kin and non-kin, insufficient genetic distance in outbreeding, or the population structure could explain these results.

Sex allocation and sexual selection have been heavily studied, but rarely linked. In this thesis I investigated the interface between them in the gregarious parasitoid wasp Nasonia vitripennis, both directly and through their interactions with the mating system and sexual conflict. Chapter 2 investigated sexual selection and mating at the natal site: earlier eclosing males mated more females independently of body size. Nasonia follows Local Mate Competition, which describes how a female laying eggs alone on a patch of resources (a so-called single-foundress) should lay an extremely female-biased brood to minimise competition between her sons, yet ensure all her daughters are fertilised. Based on this I predicted that males with with fewer brothers would be better inseminators. Despite finding significant among-strain variation in (1) single-foundress sex ratio, (2) mate competitiveness when alone and (3) when in competition, (4) sperm resources, but not (5) sperm-depletion (Chapters 3 & 4), I did not find the predicted relationship. Conversely males from strains with more brothers had a higher mating success under competition (Chapter 3) leading to the question: does mating success select on sex ratio or vice versa? Either way it is a result of an interaction between sexual selection and sex allocation. Chapter 5 investigated the role of male post-copulatory courtship on female re-mating, and found that among- strain variation in female re-mating was not associated with variation in the duration of the post-copulatory courtship. Chapter 6 reviewed sexual conflict in the Hymenoptera: their haplodiploid genetics, newly sequenced genomes and varied life- histories provides a base for future research to build on. Finally I highlight the novel links between sexual selection, sex allocation, sexual conflict and the mating system found during my studies that will hopefully prompt future research on this topic.

This project describes various aspects of the breeding ecology and behaviour of the brown falcon Falco berigora, a common but poorly study Australian raptor. In particular it examines (a) the main influences on reproductive success; (b) tests predictions of theories proposed to explain the evolution and maintenance of sexual size dimorphism (RSD; females the larger sex) in raptors; and (c) investigates sex allocation patterns in the light of current sex ratio and parental investment theory. The study was conducted between July 1999 and June 2002 approximately 35 km southwest of Melbourne, at the Western Treatment Plant (WTP), Werribee (38°0’S 144°34’E) and surrounds, a total area of approximately 150 km2.¶ · In all plumage and bare part colouration of 160 free-flying falcons was described. The majority of variation in these characters could be attributed to distinct age and/or sex differences as opposed to previously described colour ‘morphs’.¶ · Nestling chronology and development is described and formulae based on wing length derived for determining nestling age. An accurate field-based test for determining nestling sex at banding age is also presented.¶ · Strong sex role differentiation was apparent during breeding; typical of falcons females performed most parental duties whilst males predominantly hunted for their brood and partner. Based on observations of marked individuals, both sexes of brown falcons aggressively defended mutual territories throughout the year, with just 10% of each sex changing territories during the entire study period. Males performed territorial displays more frequently than females, the latter rarely displaying alone.¶ · The diet of the population as a whole was very broad, but within pairs both sexes predominantly specialised on either lagomorphs, small ground prey (e.g. house mice Mus musculus), small birds, large birds or reptiles, according to availability.¶ · Reproductive parameters such as clutch size and the duration of parental care were constant across all years, however marked annual differences in brood size and the proportion of pairs breeding were evident.¶ · Age was an important influence upon reproductive success and survival, with immature birds inferior to adults in both areas. However, interannual differences were by far the most influential factor on breeding success and female survival. Heavy rain downpours were implicated as the main determinant of reproductive success and adult female mortality in a population largely devoid of predation or human interference.¶ · Female-female competition for territorial vacancies was intense; larger adult females were more likely to be recruited and once breeding fledged more offspring. In contrast, male recruitment and breeding success was unrelated to either body size or condition indices, although smaller immature males were more likely to survive to the next breeding season. This directional selection is consistent only with the predictions of the intrasexual competition hypothesis.¶ · Despite marked RSD (males c. 75% of female body mass), throughout the nestling phase female nestlings did not require greater quantities of food than their male siblings. However, female parents fed their last-hatched sons but not daughters, resulting in the complete mortality of all last-hatched female offspring in focal nests. Given last-hatched nestlings suffered markedly reduced growth rates and female, but not male, body size is important in determining recruitment patterns, the biased allocation amongst last-hatched offspring is likely to reflect differing benefits associated with investing in small members of each sex, consistent with broad-scale Trivers-Willard effects. Recruitment patterns support this, with surviving last-hatched females, in contrast to males, unable to gain recruitment into the breeding population upon their return to the study site.¶ Thus selection appears to act at the nestling, immature and adult stages to maintain RSD in the focal population. Larger females were favoured in the nestling phase, at recruitment and once breeding had greater reproductive success. In contrast, selection favoured a reduction or maintenance of immature male size as smaller birds had a greater chance of survival in the year following recruitment than their larger counterparts; thereafter male size was unimportant. Together, this directional selection favouring increased female competitive ability is consistent only with the predictions of the intrasexual competition hypothesis, which appears the most probable in explaining the maintenance and perhaps evolution of RSD in raptors.

Thesis (Ph. D.)--Michigan State University. Dept. of Zoology, Program in Ecology, Evolutionary Biology, and Behavior, 2008.
Title from PDF t.p. (viewed Aug. 19, 2009). Includes bibliographical references (p. 88-95). Also issued in print.

The Silver Gull is a small gull (265 - 450g), which exhibits sexual dimorphism, with males larger than females. It has a protracted laying period of about 8 months over the winter on Penguin Island in Western Australia. The Silver Gull was studied on Penguin Island from 2000 to 2002. Completed clutches were removed from breeding pairs to induce repeat laying in order to determine the effect of increased reproductive effort on maternal body condition, egg production ability, offspring sex ratio and chick rearing capacity. Increased egg production had no significant effect on maternal body condition as measured by condition index, derived from mass divided by a measure of skeletal size. The seasonal period, divided into thirty-day intervals, had a significant impact on female condition index, with a decline in condition toward the end of the breeding season. While male condition also appeared to decline at the end of the season, this pattern was not significant. The initiation of laying varied between the three years of the study. The earliest occurred in 2000, which also experienced earlier rainfall than the later two years. Egg size and mass decreased throughout the breeding season although the number of eggs in a clutch did not decline. The size and mass of the eggs was significantly affected by the laying history of the parents, although this effect was dependent on the year in which the eggs were produced. The minimum interval required by Silver Gulls to replace a lost clutch is about 14 days. This interval increased from the start of the breeding season, but then declined toward the end, as summer was approaching. Laying interval increased significantly as the number of clutches produced by the parents also increased, up to 4 clutches in total. As more clutches were produced past this point, the laying interval became shorter. The probability of a replacement clutch being produced after clutch removal, declined as the clutch number increased and as the season progressed. Individuals that laid clutches with a larger mean mass were more likely to lay a replacement clutch. Increasing reproductive output caused a decline in the proportion of clutches that were replaced after clutch removal. The proportion of clutches that were replaced also varied between the years with the highest rates of replacement seen in 2000 which was also the year that experienced the earliest start in laying. The size of the original clutch in terms of its mean mass and volume was related to the size of the replacement clutch, but this relationship varied according to the timing of laying. During 2000 and 2001 male offspring predominated in the first two clutches produced by Silver Gulls. Further clutches that were produced demonstrated a sex ratio skewed toward females, the smaller sex in this species. Offspring sex ratio was close to equality in 2002 with very little effect caused by increased egg production. There was no effect of year, season or the laying history of the parents on hatching success. Growth rate in chicks was influenced by the year in which the chick hatched, the period during the season in which the chicks hatched, its sex and the laying history of the parents. The relationship between chick growth and the laying history, however, was complex with no consistent pattern emerging in terms of the performance of chicks from each treatment group. While the chicks from control groups generally grew faster than the chicks from manipulated parents, those individuals that were laid or raised by manipulated parents that had laid at least three clutches in total also performed well. Using the two main measures of reproductive success in the current study, egg production and chick rearing, those birds that were induced to lay multiple replacement clutches, were able to maintain a high level of condition and reproductive success. It is proposed that in the Silver Gull, only those individuals with a high level of condition continue to lay replacement clutches. If the female is unable to produce well provisioned eggs with a high chance of success, the breeding attempt is abandoned. Despite no loss of condition detected in female Silver Gulls with increasing clutch number, there was a significant shift in the offspring sex ratio toward females, indicating that strategies were in place to cope with the increased reproductive effort incurred as a consequence of repeat laying. Protracted laying in this species allows replacement of lost clutches only after maternal condition has been regained after laying.

The Silver Gull is a small gull (265 - 450g), which exhibits sexual dimorphism, with males larger than females. It has a protracted laying period of about 8 months over the winter on Penguin Island in Western Australia. The Silver Gull was studied on Penguin Island from 2000 to 2002. Completed clutches were removed from breeding pairs to induce repeat laying in order to determine the effect of increased reproductive effort on maternal body condition, egg production ability, offspring sex ratio and chick rearing capacity. Increased egg production had no significant effect on maternal body condition as measured by condition index, derived from mass divided by a measure of skeletal size. The seasonal period, divided into thirty-day intervals, had a significant impact on female condition index, with a decline in condition toward the end of the breeding season. While male condition also appeared to decline at the end of the season, this pattern was not significant. The initiation of laying varied between the three years of the study. The earliest occurred in 2000, which also experienced earlier rainfall than the later two years. Egg size and mass decreased throughout the breeding season although the number of eggs in a clutch did not decline. The size and mass of the eggs was significantly affected by the laying history of the parents, although this effect was dependent on the year in which the eggs were produced. The minimum interval required by Silver Gulls to replace a lost clutch is about 14 days. This interval increased from the start of the breeding season, but then declined toward the end, as summer was approaching. Laying interval increased significantly as the number of clutches produced by the parents also increased, up to 4 clutches in total. As more clutches were produced past this point, the laying interval became shorter. The probability of a replacement clutch being produced after clutch removal, declined as the clutch number increased and as the season progressed. Individuals that laid clutches with a larger mean mass were more likely to lay a replacement clutch. Increasing reproductive output caused a decline in the proportion of clutches that were replaced after clutch removal. The proportion of clutches that were replaced also varied between the years with the highest rates of replacement seen in 2000 which was also the year that experienced the earliest start in laying. The size of the original clutch in terms of its mean mass and volume was related to the size of the replacement clutch, but this relationship varied according to the timing of laying. During 2000 and 2001 male offspring predominated in the first two clutches produced by Silver Gulls. Further clutches that were produced demonstrated a sex ratio skewed toward females, the smaller sex in this species. Offspring sex ratio was close to equality in 2002 with very little effect caused by increased egg production. There was no effect of year, season or the laying history of the parents on hatching success. Growth rate in chicks was influenced by the year in which the chick hatched, the period during the season in which the chicks hatched, its sex and the laying history of the parents. The relationship between chick growth and the laying history, however, was complex with no consistent pattern emerging in terms of the performance of chicks from each treatment group. While the chicks from control groups generally grew faster than the chicks from manipulated parents, those individuals that were laid or raised by manipulated parents that had laid at least three clutches in total also performed well. Using the two main measures of reproductive success in the current study, egg production and chick rearing, those birds that were induced to lay multiple replacement clutches, were able to maintain a high level of condition and reproductive success. It is proposed that in the Silver Gull, only those individuals with a high level of condition continue to lay replacement clutches. If the female is unable to produce well provisioned eggs with a high chance of success, the breeding attempt is abandoned. Despite no loss of condition detected in female Silver Gulls with increasing clutch number, there was a significant shift in the offspring sex ratio toward females, indicating that strategies were in place to cope with the increased reproductive effort incurred as a consequence of repeat laying. Protracted laying in this species allows replacement of lost clutches only after maternal condition has been regained after laying.

The Silver Gull is a small gull (265 - 450g), which exhibits sexual dimorphism, with males larger than females. It has a protracted laying period of about 8 months over the winter on Penguin Island in Western Australia. The Silver Gull was studied on Penguin Island from 2000 to 2002. Completed clutches were removed from breeding pairs to induce repeat laying in order to determine the effect of increased reproductive effort on maternal body condition, egg production ability, offspring sex ratio and chick rearing capacity. Increased egg production had no significant effect on maternal body condition as measured by condition index, derived from mass divided by a measure of skeletal size. The seasonal period, divided into thirty-day intervals, had a significant impact on female condition index, with a decline in condition toward the end of the breeding season. While male condition also appeared to decline at the end of the season, this pattern was not significant. The initiation of laying varied between the three years of the study. The earliest occurred in 2000, which also experienced earlier rainfall than the later two years. Egg size and mass decreased throughout the breeding season although the number of eggs in a clutch did not decline. The size and mass of the eggs was significantly affected by the laying history of the parents, although this effect was dependent on the year in which the eggs were produced. The minimum interval required by Silver Gulls to replace a lost clutch is about 14 days. This interval increased from the start of the breeding season, but then declined toward the end, as summer was approaching. Laying interval increased significantly as the number of clutches produced by the parents also increased, up to 4 clutches in total. As more clutches were produced past this point, the laying interval became shorter. The probability of a replacement clutch being produced after clutch removal, declined as the clutch number increased and as the season progressed. Individuals that laid clutches with a larger mean mass were more likely to lay a replacement clutch. Increasing reproductive output caused a decline in the proportion of clutches that were replaced after clutch removal. The proportion of clutches that were replaced also varied between the years with the highest rates of replacement seen in 2000 which was also the year that experienced the earliest start in laying. The size of the original clutch in terms of its mean mass and volume was related to the size of the replacement clutch, but this relationship varied according to the timing of laying. During 2000 and 2001 male offspring predominated in the first two clutches produced by Silver Gulls. Further clutches that were produced demonstrated a sex ratio skewed toward females, the smaller sex in this species. Offspring sex ratio was close to equality in 2002 with very little effect caused by increased egg production. There was no effect of year, season or the laying history of the parents on hatching success. Growth rate in chicks was influenced by the year in which the chick hatched, the period during the season in which the chicks hatched, its sex and the laying history of the parents. The relationship between chick growth and the laying history, however, was complex with no consistent pattern emerging in terms of the performance of chicks from each treatment group. While the chicks from control groups generally grew faster than the chicks from manipulated parents, those individuals that were laid or raised by manipulated parents that had laid at least three clutches in total also performed well. Using the two main measures of reproductive success in the current study, egg production and chick rearing, those birds that were induced to lay multiple replacement clutches, were able to maintain a high level of condition and reproductive success. It is proposed that in the Silver Gull, only those individuals with a high level of condition continue to lay replacement clutches. If the female is unable to produce well provisioned eggs with a high chance of success, the breeding attempt is abandoned. Despite no loss of condition detected in female Silver Gulls with increasing clutch number, there was a significant shift in the offspring sex ratio toward females, indicating that strategies were in place to cope with the increased reproductive effort incurred as a consequence of repeat laying. Protracted laying in this species allows replacement of lost clutches only after maternal condition has been regained after laying.

Research on reward allocations has consistently found differences in the manner in which men and women allocate rewards between themselves and others (Kahn, O'Leary, Krulewitz, & Lamm, 1980; Major & Adams, 1984; Major & Deaux, 1982). Overall, the research seems to suggest that when asked to divide a reward between themselves and a partner, men tend to use the equity norm to allocate rewards; whereas, women tend to use the equality norm to allocate rewards. However, a number of studies have been conducted which seem to demonstrate that a variety of situational g factors mediate the gender of allocator effects such as input level of the allocator and his/her co-workers, gender of the co-worker, expectancy of future interaction with the co-worker, and type of reward allocation. The purpose of the present research was two-fold: (1) to examine individual differences influencing an allocator's choice of an allocation strategy, such as how anticipation of future interaction with the recipients of an allocation decision would influence an allocator's reward allocation; and (2) whether a person‘s self-esteem level might impact on how an individual might allocate a reward. In general, the results of the current research suggest that previously observed differences between men's and women's allocations may not reflect true underlying differences between the gender; in terms of their preferences for allocation strategies. Allocation strategies appeared to vary as a function of the gender and input levels of the recipients of the reward and whether the type of allocation decision was a joint or independent situation. Both men and women tended to allocate rewards either equitably or using a compromise between equity and equality. Self-esteem was also found to influence the amount of the reward men and women allocated to the high performer and to themselves. Unfortunately, disclosure of allocation was not found to have a major effect upon how subjects allocated rewards. Several alternative explanations for these results are discussed.
Ph. D.

I investigated the patterns of male and female flower production in two populations of a monoecious, self-compatible, prostrate vine, Apodanthera undulata Gray (Cucurbitaceae). Small, and probably young, plants produce no flowers. Larger and older plants produce only male flowers, while a somewhat greater threshold size is necessary for female flower production. Beyond these threshold effects, femaleness, a proportional measure of allocation to female function, did not increase with plant size. Thus, allocation to both male and female functions increased with size. In contrast, femaleness decreased with increasing flower production; plants with many flowers opened relatively more male flowers than plants with fewer flowers. This trend, which seemed stronger in the low density population, can have important effects on pollinator behavior and thus on pollen dispersal and receipt. Femaleness was positively correlated between years for all plants and for all cosexes, plants that produced both male and female flowers. Thus, plants that opened only male flowers one year were likely to open only male flowers the next year. Similarly, cosexes were likely to be cosexes again in the following year, with similar femaleness values. Approximately 10% of all flowering plants changed gender group. These patterns suggested that all plants were male until they reached a certain size and that plants had an intrinsic femaleness value due to either genotype, microsite or environmental effects. Finally, some of the reproductive consequences of these gender allocation patterns were investigated. The factors determining success, such as predation and rainfall, were unpredictable between populations and years. Unless success was especially low (i.e., few fruits matured in the population), success through male and female functions were positively correlated, as could be predicted for a monoecious species. The gains for male success were greater with increasing allocation to that function in the high density as opposed to the low density population. This suggested that plants in the high density population should allocate more to male function, as was observed. Though preliminary, these data support the predictions of sex allocation theory for cosexual species.

Field surveys of Strongylocentrotus purpuratus demonstrated that concentrations of natural sunscreens, mycosporine-like amino acids (MAAs), were higher in females than males for both gonadal and epidermal tissues, increased in ovaries as spawning season approached, and were influenced by the sea urchins’ microhabitat. Sea urchins occupying burrows, or “pits”, had lower concentrations of MAAs than those outside pits, suggesting a trade-off between physical and UV protection. Overall, UV irradiance did not influence MAA accumulation in gonadal tissues. However, males increased their allocation of MAAs to epidermal tissues in the microhabitat with the highest irradiance. Relative concentrations of individual MAAs were similar for epidermal tissues from both sexes and ovaries, providing broadband UVA/UVB absorbance, but testes contained principally one MAA, palythine. This is the first study to demonstrate that S. purpuratus and eight species of macroalgae in California have MAAs, and that the concentrations can be influenced by microhabitat.

Monoecy, the production of distinct male and female flowers on the same plant, is an important, though little studied, sexual strategy in the rainforest understory. This study of a monoecious plant discovered a cue to induce flowering, explored the interplay of gender constraint vs. plasticity in a natural population, and tested possible causes of gender in two laboratory experiments. An experiment in the lab found that reduced photoperiod for three weeks is an unambiguous cue for flowering. The remarkably long inductive period is followed by a long and variable period of floral initiation. This results in only partial synchronization of flowering among plants in a patch, which enhances mating opportunities in this protandrous plant. Inflorescence architecture is highly constrained, and ideally produces a phenotypic gender (proportion female) of about 0.5. However, in the forest at Las Cruces, Costa Rica, most plants were less female than predicted, mostly through abortion of female buds. Plants showed gender plasticity between and within years. Large plants produced more flowers and were more female in gender, and less variable in gender, than small plants. Reproduction was poorly correlated with environmental resource availability, measured as canopy openness, soil moisture, pH, and soil phosphorus, ammonium and nitrate. Phenotypic selection analysis on seed production suggests an optimal gender of 50-60% female, yet plasticity to be less female than this optimum, and in particular to express only male function, has been maintained. In a factorial experiment in the lab, high light or high nitrogen caused plants to produce more flowers and to be proportionally more female, and larger in weight, than low light or nitrogen. The effects of light and nitrogen on reproduction, plant size, and leaf greenness suggest an energy based determination of gender. Gender may be mostly influenced by plant size, but sometimes also opportunistically by environment. Inoculation with mycorrhizas caused plants to be less female in gender, and smaller in weight, than plants that were not inoculated. This suggests a net cost of mycorrhizas under experimental conditions, and supports the emerging view of the mycorrhizal symbiosis as not necessarily mutualistic under all circumstances.

Life-history theory proposes that different activities, such as growth, maintenance and reproduction compete for limited resources and therefore, life-history traits are bound together by physiological trade-offs. In dioecious species, females are assumed to invest a higher amount of resources in reproduction in comparison with males and this higher investment in reproduction is then assumed to have numerous consequences for the expression of other life-history traits. Some recent papers have, however, suggested that although common, this investment pattern may not be the case in all dioecious plant species. One notable exception is Silene latifolia. Therefore, I examined whether the male sex could be investing more in reproduction than females in a closely related Silene species, Silene dioica. This study was carried out on three islands in the Skeppsvik Archipelago, Umeå, where I examined possible differences between the sexes in different life history traits. On each island, 20 patches were laid out in two different successional zones. In each patch, flowering date was recorded and stem diameter, length and width of cauline leaves, flower diameter, and number of open flowers on male and female plants was measured. At the end of the study, flowering stems were collected and thereafter dried so they could be weighed to estimate biomass allocated to male and female vegetative and reproductive structures. The hypothesis that males of S. dioica should have a higher reproductive cost seemed to be confirmed since males started flowering earlier, produced more and larger flowers, produced smaller and fewer leaves and thinner stems. The males also allocated a greater proportion of their total biomass to reproductive parts and as a consequence, had a higher sink to source ratio. This study has shown that there are exceptions to the "rule" of females having a higher cost of reproduction and when doing research on dioecious species, it is important not to assume that only one and the same sex has the higher investment in reproduction in all species. This higher cost may have consequences for survival and reproductive fitness and can select for differences in other ecological traits, such as phenology, growth, chemical composition and morphology, which could in turn affect the competitive ability and the susceptibility to herbivores and pathogens.

Les ressources étant limitées, les organismes doivent les partager entre les différents traits associés à leur valeur sélective. L'investissement optimal dans chacun de ces traits dépend des conditions environnementales et les individus sont sélectionnés pour ajuster leur stratégie d'allocation en conséquence. La théorie de la compétition locale pour l'accouplement (LMC) illustre bien cette hypothèse. Cette théorie prédit que lorsque qu'une population est structurée, de sorte de l'accouplement se fait localement et que des mâles apparentés sont en compétition pour la reproduction, les femelles devraient biaiser leur sexe ratio en faveur des filles. Bien que cette théorie ait été soutenue par de nombreuses études empiriques, les processus mécanistiques et évolutifs sous-jacents sont très peu connus. Dans cette thèse, j'aborde ces processus chez l'acarien haplo-diploïdeTetranychus urticae. Dans un premier temps, je montre que chez cette espèce, la taille des œufs es tutilisée par les femelles comme mécanisme d'ajustement du sexe-ratio. En effet, les œufs plus gros ont une plus grande probabilité de devenir femelle, et la taille des œufs produits augmente avec l'intensité de la LMC. Dans un second temps, à travers une approche d'évolution expérimentale, j'apporte le premier exemple empirique d'évolution du sexe-ratio en réponse à la LMC.En plus de varier avec les conditions environnementales, la stratégie optimale d'allocation desressources diffère souvent entre mâles et femelles, générant des conflits sexuels. Dans cette thèse,j'étudie les conséquences de tels conflits sur la stratégie reproductive des femelles chez Tetranychusurticae. Je montre notamment que l'accouplement induit une réduction de la longévité et de la fécondité, accompagnée d'une augmentation de la taille des œufs
Because resources are limited, organisms are constrained to divide their resources between fitness components. The optimal investment into these traits can vary with environmental conditions, so that individuals are selected to adjust their allocation strategy accordingly. The theory of local mate competition (LMC) illustrates this hypothesis. This theory predicts that when populations arestructured, so that mating takes place locally and related males compete for mates, mothers should biastheir sex ratio towards females. Although this theory has been supported by many empirical studies,mechanistic and evolutionary processes underlying sex ratio adjustment remain poorly understood. Inthis thesis, I address these issues, using the haplodiploid spider mite Tetranychus urticae. First, I show that in this species, egg size is used as a mechanism of sex ratio adjustment. Indeed, larger eggs aremore likely to become female, and female spider mites use this property to adjust their sex ratio inresponse to LMC, increasing egg size with the intensity of LMC. Second, through an experimentalevolution approach, I provide the first empirical evidence that the sex ratio can evolve in response toLMC.In addition to varying with environmental conditions, the optimal strategy of resourceallocation also generally differs between male and females. Because of such conflicts, males havedeveloped adaptations aimed at manipulating the way by which females allocate their resources. Iinvestigate the consequences of mating for female reproductive strategies in spider mites. I find that mating induces a decrease of both longevity and fecundity, and an increase of egg size

The Trivers-Willard hypothesis (TWH) states that parents in good conditions will bias the sex ratio toward sons and parents in poor conditions will bias the sex ratio toward daughters. The present study contributes to literature in several ways: a large, general, country population data set (N= 1 401 851) from modern contemporary society; first study in the Czech Republic; an inclusion of air pollution into the TWH estimation; and a more detailed focus on stillbirths. With the natality microdata from the Czech Statistical Office and data concerning the level of air pollution in the Czech Republic from the Czech Hydrometeorological Institute, I analyze if the biological and socio-economics status of mothers and the characteristics of our surroundings (air pollution) affect the sex of children. The results are insignificant or not robust across specifications. I identified three hypotheses which are most likely the reason for the insignificant results: a non-inclusion of the biological and socio-economical status of a father, insufficient diversity or evolutionarily novel environment in the Czech Republic. As a conclusion, the presented evidence suggests that stillbirths are random in the Czech Republic and that the sex ratio is not affected by the socio-economics status of mothers or the characteristics of our surroundings (pollution).

The allocation of resources to male or female progeny, or to male or female reproductive function more generally, is one of the most important life history decisions a sexually reproducing individual must ever make. Sex determination is thus a fundamental process, yet the mechanisms which control it are surprisingly diverse. In this thesis, I examine sex determination in the plant species Mercurialis annua L. (Euphorbiaceae). I assess the mechanism of sex determination operating in dioecious and androdioecious populations of M. annua and also investigate the conservation and evolution of sex-determining mechanisms across the annual mercury clade, the lineages of which display exceptional variation in sexual system. First, using crosses, I establish that sex in dioecious M. annua is controlled by a single-locus genetic mechanism, consistent with recent work that identified a single male-linked DNA marker in the species. My search for new sex-linked genes revealed none, however, suggesting that M. annua possesses at most a small non-recombining region around sex-determining loci. Why many dioecious plants lack heteromorphic sex chromosomes is still poorly understood and I consider explanations for this. I extend my investigation by comparing genetic diversity between loci that differ in their linkage to the sex-determining locus. I find a single male-linked marker to possess significantly lower diversity than autosomal loci, but no difference in the diversity of partially sex-linked and non-sex-linked genes. I also assess the conservation of a sex-linked marker among annual mercury lineages and conduct crosses between lineages to examine the conservation of sex determination. My findings indicate a conserved mechanism of single-locus genetic sex determination and I consider the role polyploidisation and hybridisation have played in sexual system evolution and the modification of sex-determining mechanisms in the clade. Finally, I assess the presence of environmental sex determination in androdioecious M. annua, concluding that although male frequency is not influenced by growing density, a degree of sexual lability exists in the lineage.

This thesis focuses on reproduction in a simultaneous hermaphrodite with internal fertilization; the nudibranch Aeolidiella glauca. Unlike most other nudibranchs, where copulation is the rule, A. glauca was found to transfer sperm via external spermatophores that were attached to the partner's back. Despite elaborate courtship the actual spermatophore transfer, which always involved two animals only, was of short duration. In most matings (88%) spermatophores were reciprocally exchanged.

A. glauca was further found to be very promiscuous. During mating and sperm transfer the receiver exerts considerable control over sperm, and manipulative behaviours designed to increase the donor's reproductive success are thus likely to have evolved. An example of such manipulative behaviour may be A. glauca's unique spermatophore avoidance behaviour. I found that slugs carrying a sign of previous mating activity, i.e. a spermatophore, were discriminated against in a situation where mate choice was possible. The presence of spermatophores was further found to reduce slugs' ability to interrupt matings, and displace other slugs. Body size, however, had no direct effect on displacement in A. glauca as small slugs interrupted matings as successfully as large ones. Furthermore, pair formation and mating were found to be random with respect to size. This was true also for pairs formed in the field.

In addition to mate choice hermaphrodites may increase their reproductive success by differential sex allocation. I tested whether differing mate encounter rates had any effects on allocation to male and female function in A. glauca. Slugs with more mating opportunities mated more, and had higher proportional spermatophore production that others. As predicted they also laid significantly fewer eggs than slugs presented with partners less often.

R??sum?? : La reproduction entra??ne des d??penses ??nerg??tiques importantes chez les femelles mammif??res. Ces d??penses sont suppos??es diminuer l'??nergie disponible pour d'autres traits positivement corr??l??s ?? l'aptitude ph??notypique et augmenter les besoins d'alimentation. Toutefois, des diff??rences individuelles dans la capacit?? d'acquisition et d'allocation peuvent masquer l'impact n??gatif de l'effort reproducteur. La manipulation exp??rimentale de l'effort reproducteur et le contr??le statistique des effets individuels sont deux approches puissantes et compl??mentaires mises en ??uvre dans le cadre de mon ??tude afin de contr??ler pour l'h??t??rog??n??it?? individuelle. Elles ont permis de montrer clairement un co??t de la reproduction chez le kangourou gris de l'Est (Macropus giganteus). Dans un premier temps, nous avons trouv?? que le co??t de la reproduction affectait le montant d'??nergie allou?? ?? certaines fonctions somatiques (CHAPITRE I). L'effort reproducteur diminuait le gain de masse et la croissance des jambes pour des intervalles de capture sup??rieurs ?? deux ans. Chez les femelles non manipul??es, un effet n??gatif sur le gain de masse ??tait aussi observable pour un intervalle inf??rieur ?? 3 ans. ?? l'??chelle de deux ??v??nements successifs de reproduction, le gain de masse et dans une moindre mesure la croissance des bras, mais non des jambes diminuaient avec un effort reproducteur plus important ?? la pr??c??dente reproduction. Ensuite, nous avons d??montr?? qu'il y avait un co??t de la reproduction en terme de futur succ??s reproducteur (CHAPITRE II). Les individus dont l'effort reproducteur avait ??t?? diminu?? exp??rimentalement produisaient davantage de jeunes qui survivaient au stade 'LPY', ??g??s approximativement de 7 mois, que les femelles contr??les. Ils diminuaient ??galement davantage leur taux de reproduction en allongeant l'intervalle entre les naissances, mais la survie au sevrage n'??tait pas affect??e. Le CHAPITRE III montre que les femelles adaptaient leur comportement alimentaire en fonction de leur statut reproducteur. En comparaison avec les individus manipul??s ou ayant perdu leur jeune, les femelles allaitantes augmentaient leur temps pass?? ?? s'alimenter durant la journ??e, l'intensit?? de leurs bouch??es et de leur mastication sans impliquer de compromis avec la vigilance. Nous avons aussi d??couvert que la survie au sevrage du jeune pr??c??dent menait ?? une augmentation du taux de bouch??es pour l'ann??e en cours. Les CHAPITRES I et II ont mis en ??vidence l'effet non n??gligeable des diff??rences individuelles sur la d??tection des co??ts de la reproduction. En effet, en l'absence de manipulation exp??rimentale ou de contr??le statistique, aucun compromis n'??tait d??tect?? autant en terme de croissance que de prochaine reproduction. Au contraire, des corr??lations positives entre l'effort reproducteur et les autres traits ont ??t?? trouv??es. Le CHAPITRE I sugg??rait notamment que cette variabilit?? du succ??s reproducteur ??tait li??e ?? l'h??t??rog??n??it?? individuelle dans le gain de masse maternelle qui augmentait la survie du jeune. Dans le CHAPITRE II, une corr??lation positive entre les probabilit??s d'avoir un 'LPY' lors de deux ??v??nements successifs de reproduction sugg??rait que certaines femelles ??taient capables de mener ?? bien ou non leur reproduction, mais cela ind??pendamment de l'effort reproducteur pr??c??dent. Enfin dans le dernier CHAPITRE (III), l'effet al??atoire ??tait significatif dans l'analyse de diff??rents comportements d'alimentation, ce qui pourrait ??tre li?? aux diff??rences de gain de masse des femelles pr??sent??es dans le CHAPITRE I. Certaines contraintes individuelles affectant le co??t de la reproduction ont ??t?? identifi??es. La masse et la condition corporelle augmentaient le succ??s reproducteur et diminuaient l'intervalle entre deux naissances successives (CHAPITRES I et II), mais contrairement ?? de pr??c??dentes ??tudes le comportement d'alimentation des femelles n'??tait pas affect?? par leur masse (CHAPITRE III). L'??ge des individus avait ??galement une influence. Les jeunes femelles croissaient davantage, avaient aussi une prise alimentaire plus importante et subissaient un co??t de reproduction sup??rieur. Ce dernier se traduisait par un taux d'??chec plus ??lev?? ?? la reproduction suivante si les jeunes femelles avaient eu un jeune l'ann??e pr??c??dente (CHAPITRES I, II et III). Des contraintes environnementales fortes influen??aient la reproduction des femelles. La croissance, le succ??s reproducteur, l'intervalle entre les naissances et les comportements d'alimentation variaient suivant le site et l'ann??e d'??tude. Le site du Promontory et l'ann??e 2011 apparaissaient particuli??rement limitants. En effet en 2011, le gain de masse et le succ??s reproducteur ont diminu?? et l'intervalle de naissance et la prise de nourriture pour les femelles allaitantes ont augment?? (CHAPITRE I,II et III). Nous cherchions ??galement ?? mettre au jour une allocation diff??rentielle des m??res suivant le sexe de leur jeune. Si le co??t sup??rieur d'avoir un m??le par rapport ?? une femelle ??tait ??vident quant aux taux de bouch??es (CHAPITRE III), il s'est av??r?? plus difficile ?? d??tecter sur d'autres traits. ?? Anglesea, les jeunes m??res avaient moins de probabilit?? d'avoir un jeune qui atteigne le stade 'LPY' apr??s avoir eu un fils qu'une fille (CHAPITRE II). Toutefois, des r??sultats contraires ?? nos attentes ont ??t?? trouv??s, du moins au premier abord, sur la croissance et le succ??s reproducteur subs??quent. Ainsi, les femelles qui avaient eu une fille perdaient davantage de masse (CHAPITRE I) et avaient g??n??ralement une probabilit?? moindre de produire un jeune qui atteigne le stade 'LPY' ou qui soit sevr?? par la suite (CHAPITRE II). En revanche, l'intervalle de naissance n'??tait pas diff??rent suivant le sexe du jeune alors qu'il ??tait fortement affect?? par le co??t de la reproduction d??montr?? gr??ce ?? la manipulation, invoquant une autre explication qu'un co??t sup??rieur des filles par rapport aux fils. En effet, les femelles qui ??taient en mauvaise condition corporelle gagnaient de la masse quand elles produisaient une fille, mais pas un fils (CHAPITRE I). De surcro??t, les jeunes m??res avaient moins de chances de sevrer un jeune ?? l'??v??nement de reproduction suivant si elles avaient eu un fils plut??t qu'une fille, et le succ??s reproducteur des m??res des fils n'??tait plus diff??rent de celui des m??res des filles dans les ann??es plus difficiles (CHAPITRE II). Enfin, les m??res des fils augmentaient la quantit?? de nourriture ing??r??e si elles avaient sevr?? un jeune l'ann??e pr??c??dente, mais les m??res des filles la diminuaient. Ces diff??rents r??sultats sugg??raient fortement qu'un ajustement du sexe-ratio ??tait utilis?? quand les ressources individuelles ou environnementales contraignaient davantage la reproduction. En conclusion, pour limiter le d??calage entre les besoins ??nerg??tiques et la disponibilit?? en nourriture, les femelles chez le kangourou gris de l'Est pourraient modifier l'allocation de leurs ressources ?? la reproduction en reportant la prochaine mise bas et en produisant un jeune du sexe le moins co??teux en accord avec les contraintes individuelles et environnementales. Ces r??sultats soulignent l'importance d'??tudes avec un suivi individuel sur plusieurs ann??es afin de pouvoir comprendre la variabilit?? des strat??gies de reproduction et leurs cons??quences sur la dynamique des populations. // Abstract : Reproduction in living beings, particularly in female mammals that produce milk, is costly, potentially involving trade-offs with life-history traits if resources are limited and an increase in foraging effort. Individual differences may, however, hide the negative effects of this cost on life-history traits. I used two powerful and complementary approaches, to deal with individual heterogeneity: experimental manipulation of reproductive effort and statistical control of individual effect. Using both approaches, I investigated the effect of presence, size and sex of young on growth, subsequent reproduction and individual foraging behaviours of females. I used data of tagged free-ranging eastern grey kangaroos (Macropus giganteus) collected over six years at five study sites in Victoria, Australia. There was a clear cost of reproduction. Reproductive effort decreased mass gain and limb growth for inter-capture intervals greater than two years. Over two successive reproductive events, mass gain and arm growth were reduced but leg growth was independent of reproductive effort (CHAPTER II).In addition, survival to Large Pouch Young ('LPY') stage, about 7 months of age, was higher and birth rate lower in manipulated compared to control females but survival to weaning was not affected (CHAPTER III). CHAPTER IV shows that lactating females cope with current reproductive costs by increasing ivtime spent foraging as well as bite and chewing rates without decreasing vigilance comparedto non lactating ones. Bite rate was also greater for females that weaned a young at the previous reproductive event. My study supports reproductive cost hypothesis while showing substantial individual differences. To limit mismatch between energetic needs and resource availability, females of eastern grey kangaroo could modify resource allocation to reproduction by delaying birth date of subsequent young and producing the less costly sex according to individual and environmental constrains. My thesis shows the importance of experimental approach and individual monitoring over multiple years to understand the diversity of reproductive strategies and their consequences in evolutionary ecology and population dynamic.

Résumé : La reproduction entraîne des dépenses énergétiques importantes chez les femelles mammifères. Ces dépenses sont supposées diminuer l'énergie disponible pour d'autres traits positivement corrélés à l'aptitude phénotypique et augmenter les besoins d'alimentation. Toutefois, des différences individuelles dans la capacité d'acquisition et d'allocation peuvent masquer l'impact négatif de l'effort reproducteur. La manipulation expérimentale de l'effort reproducteur et le contrôle statistique des effets individuels sont deux approches puissantes et complémentaires mises en œuvre dans le cadre de mon étude afin de contrôler pour l'hétérogénéité individuelle. Elles ont permis de montrer clairement un coût de la reproduction chez le kangourou gris de l'Est (Macropus giganteus). Dans un premier temps, nous avons trouvé que le coût de la reproduction affectait le montant d'énergie alloué à certaines fonctions somatiques (CHAPITRE I). L'effort reproducteur diminuait le gain de masse et la croissance des jambes pour des intervalles de capture supérieurs à deux ans. Chez les femelles non manipulées, un effet négatif sur le gain de masse était aussi observable pour un intervalle inférieur à 3 ans. À l'échelle de deux événements successifs de reproduction, le gain de masse et dans une moindre mesure la croissance des bras, mais non des jambes diminuaient avec un effort reproducteur plus important à la précédente reproduction. Ensuite, nous avons démontré qu'il y avait un coût de la reproduction en terme de futur succès reproducteur (CHAPITRE II). Les individus dont l'effort reproducteur avait été diminué expérimentalement produisaient davantage de jeunes qui survivaient au stade 'LPY', âgés approximativement de 7 mois, que les femelles contrôles. Ils diminuaient également davantage leur taux de reproduction en allongeant l'intervalle entre les naissances, mais la survie au sevrage n'était pas affectée. Le CHAPITRE III montre que les femelles adaptaient leur comportement alimentaire en fonction de leur statut reproducteur. En comparaison avec les individus manipulés ou ayant perdu leur jeune, les femelles allaitantes augmentaient leur temps passé à s'alimenter durant la journée, l'intensité de leurs bouchées et de leur mastication sans impliquer de compromis avec la vigilance. Nous avons aussi découvert que la survie au sevrage du jeune précédent menait à une augmentation du taux de bouchées pour l'année en cours. Les CHAPITRES I et II ont mis en évidence l'effet non négligeable des différences individuelles sur la détection des coûts de la reproduction. En effet, en l'absence de manipulation expérimentale ou de contrôle statistique, aucun compromis n'était détecté autant en terme de croissance que de prochaine reproduction. Au contraire, des corrélations positives entre l'effort reproducteur et les autres traits ont été trouvées. Le CHAPITRE I suggérait notamment que cette variabilité du succès reproducteur était liée à l'hétérogénéité individuelle dans le gain de masse maternelle qui augmentait la survie du jeune. Dans le CHAPITRE II, une corrélation positive entre les probabilités d'avoir un 'LPY' lors de deux événements successifs de reproduction suggérait que certaines femelles étaient capables de mener à bien ou non leur reproduction, mais cela indépendamment de l'effort reproducteur précédent. Enfin dans le dernier CHAPITRE (III), l'effet aléatoire était significatif dans l'analyse de différents comportements d'alimentation, ce qui pourrait être lié aux différences de gain de masse des femelles présentées dans le CHAPITRE I. Certaines contraintes individuelles affectant le coût de la reproduction ont été identifiées. La masse et la condition corporelle augmentaient le succès reproducteur et diminuaient l'intervalle entre deux naissances successives (CHAPITRES I et II), mais contrairement à de précédentes études le comportement d'alimentation des femelles n'était pas affecté par leur masse (CHAPITRE III). L'âge des individus avait également une influence. Les jeunes femelles croissaient davantage, avaient aussi une prise alimentaire plus importante et subissaient un coût de reproduction supérieur. Ce dernier se traduisait par un taux d'échec plus élevé à la reproduction suivante si les jeunes femelles avaient eu un jeune l'année précédente (CHAPITRES I, II et III). Des contraintes environnementales fortes influençaient la reproduction des femelles. La croissance, le succès reproducteur, l'intervalle entre les naissances et les comportements d'alimentation variaient suivant le site et l'année d'étude. Le site du Promontory et l'année 2011 apparaissaient particulièrement limitants. En effet en 2011, le gain de masse et le succès reproducteur ont diminué et l'intervalle de naissance et la prise de nourriture pour les femelles allaitantes ont augmenté (CHAPITRE I,II et III). Nous cherchions également à mettre au jour une allocation différentielle des mères suivant le sexe de leur jeune. Si le coût supérieur d'avoir un mâle par rapport à une femelle était évident quant aux taux de bouchées (CHAPITRE III), il s'est avéré plus difficile à détecter sur d'autres traits. À Anglesea, les jeunes mères avaient moins de probabilité d'avoir un jeune qui atteigne le stade 'LPY' après avoir eu un fils qu'une fille (CHAPITRE II). Toutefois, des résultats contraires à nos attentes ont été trouvés, du moins au premier abord, sur la croissance et le succès reproducteur subséquent. Ainsi, les femelles qui avaient eu une fille perdaient davantage de masse (CHAPITRE I) et avaient généralement une probabilité moindre de produire un jeune qui atteigne le stade 'LPY' ou qui soit sevré par la suite (CHAPITRE II). En revanche, l'intervalle de naissance n'était pas différent suivant le sexe du jeune alors qu'il était fortement affecté par le coût de la reproduction démontré grâce à la manipulation, invoquant une autre explication qu'un coût supérieur des filles par rapport aux fils. En effet, les femelles qui étaient en mauvaise condition corporelle gagnaient de la masse quand elles produisaient une fille, mais pas un fils (CHAPITRE I). De surcroît, les jeunes mères avaient moins de chances de sevrer un jeune à l'événement de reproduction suivant si elles avaient eu un fils plutôt qu'une fille, et le succès reproducteur des mères des fils n'était plus différent de celui des mères des filles dans les années plus difficiles (CHAPITRE II). Enfin, les mères des fils augmentaient la quantité de nourriture ingérée si elles avaient sevré un jeune l'année précédente, mais les mères des filles la diminuaient. Ces différents résultats suggéraient fortement qu'un ajustement du sexe-ratio était utilisé quand les ressources individuelles ou environnementales contraignaient davantage la reproduction. En conclusion, pour limiter le décalage entre les besoins énergétiques et la disponibilité en nourriture, les femelles chez le kangourou gris de l'Est pourraient modifier l'allocation de leurs ressources à la reproduction en reportant la prochaine mise bas et en produisant un jeune du sexe le moins coûteux en accord avec les contraintes individuelles et environnementales. Ces résultats soulignent l'importance d'études avec un suivi individuel sur plusieurs années afin de pouvoir comprendre la variabilité des stratégies de reproduction et leurs conséquences sur la dynamique des populations. // Abstract : Reproduction in living beings, particularly in female mammals that produce milk, is costly, potentially involving trade-offs with life-history traits if resources are limited and an increase in foraging effort. Individual differences may, however, hide the negative effects of this cost on life-history traits. I used two powerful and complementary approaches, to deal with individual heterogeneity: experimental manipulation of reproductive effort and statistical control of individual effect. Using both approaches, I investigated the effect of presence, size and sex of young on growth, subsequent reproduction and individual foraging behaviours of females. I used data of tagged free-ranging eastern grey kangaroos (Macropus giganteus) collected over six years at five study sites in Victoria, Australia. There was a clear cost of reproduction. Reproductive effort decreased mass gain and limb growth for inter-capture intervals greater than two years. Over two successive reproductive events, mass gain and arm growth were reduced but leg growth was independent of reproductive effort (CHAPTER II).In addition, survival to Large Pouch Young ('LPY') stage, about 7 months of age, was higher and birth rate lower in manipulated compared to control females but survival to weaning was not affected (CHAPTER III). CHAPTER IV shows that lactating females cope with current reproductive costs by increasing ivtime spent foraging as well as bite and chewing rates without decreasing vigilance comparedto non lactating ones. Bite rate was also greater for females that weaned a young at the previous reproductive event. My study supports reproductive cost hypothesis while showing substantial individual differences. To limit mismatch between energetic needs and resource availability, females of eastern grey kangaroo could modify resource allocation to reproduction by delaying birth date of subsequent young and producing the less costly sex according to individual and environmental constrains. My thesis shows the importance of experimental approach and individual monitoring over multiple years to understand the diversity of reproductive strategies and their consequences in evolutionary ecology and population dynamic.

Knowledge of sex allocation trade-offs with tree growth in insect-pollinated woody plants is limited, particularly in invasive plants. This study examined patterns of growth and reproductive investment in a North American invasive plant species, Triadica sebifera, I hypothesized that the energy limitations of smaller trees may result in the production of more male reproductive structures that are energetically less costly. Diameter at breast height was a significant predictor of seed and catkin mass and regression can describe these relationships across sites. Seed and catkin mass were positively correlated across sites. The relationship between the seed mass:catkin mass ratio and DBH was not significant, nor was seed mass:catkin mass and total investment. Results showed a significant positive relationship between total reproductive investment and tree size across sites. Seed mass:catkin mass ratio and reproduction investment showed substantial variation among individual trees of similar size within sites.

Conflicts of interest among family members are expected to occur over parental investment. In altricial species, individual offspring are selected to receive a larger share of parental resources than their siblings and to obtain more care than it would be optimal for parents to provide. On the other hand, parents are expected to allocate their parental investment depending on the reproductive value of individual offspring and according to the environmental conditions so to maximize their own fitness. Perinatal environment is mainly determined by parental decisions over the time and place of breeding as well as over the number of offspring produced and the effort devoted in attending the progeny, which can determine the intensity of within-brood competition and ultimately the amount of resources received by each member of the progeny. The amount of resources received by individual offspring is crucial in determining its growth, general state and viability, with consequences that can eventually carry-over into adult life. It is widely believed that the expression of the so-called begging behaviour, consisting of a diverse set of morphological and behavioural displays that offspring use to solicit care provisioning, is crucial in the resolution of the intra-familiar conflicts. The first part of the present thesis (Chapters 1-3) is concerned with intra-family communication in an altricial bird species, the barn swallow (Hirundo rustica), with special focus on the factors that may influence the expression of begging behaviour (e.g. sex, hunger level and immune challenge), and thus mediate sibling competition and parental food allocation, and ultimately cause variation in offspring general state and growth trajectories. In addition, I have examined the function of sib-sib interactions, mediated by a peculiar form of within-brood communication that occurs in the absence of parents, and their consequences for access to food in order to investigate state-dependent expression of selfish/altruistic behaviour among siblings. I have shown that solicitation of parental care considerably increases when nestlings are experimentally deprived of food and thus reliably reflects short-term need (Chapters 1-3). In addition, I have provided evidence for a fine-tuned modulation of begging behaviour by nestlings in relation to nestmate’s need: less hungry nestlings in fact reduce their competitive effort when facing a sibling in poor condition (Chapter 1) and when a nestmate performs begging displays in the absence of the attending parents (Chapter 2). Such a reduced competitiveness favours the access to food by needy kin and allows them to recover from a food deficiency. The modulation of selfishness thus assures indirect fitness benefits by enhancing survival prospects of siblings. This observation emphasizes the importance of kin selection in moulding the complex interactions among siblings for the access to limiting parental resources and shows that offspring play a crucial role in the control of allocation of parental investment (Chapters 1 and 2). Furthermore, begging intensity increases when nestlings are subjected to an immune challenge that causes a measurable deterioration in their general condition (e.g. decrease in body mass and plumage quality; Chapter 3), implying that begging behaviour can convey reliable information on individual reproductive value. Such information can thus be exploited by parents to optimally modulate allocation of care towards each member of the progeny. I have also demonstrated a sex-dependent variation in the effects of an immune challenge (e.g. feathers growth), leading to differences in the expression of begging behaviour between the sexes. However, variation in general condition does not to affect parental food allocation, likely because barn swallows adopt a ‘brood survival’ strategy whereby parents tend to promote successful fledging of all offspring rather than discriminating among their progeny (Chapter 3). The second part of my thesis (Chapters 4-5) focuses on variation of parental investment towards offspring of either sex according to spatial heterogeneity and seasonality of ecological conditions. In particular, I have examined variation in the sex ratio of first and second broods of the same barn swallow pairs in relation to nesting habitat quality (Chapter 4). In a further study I have investigated the seasonal variation in growth patterns and individual quality of male and female nestlings of the common starling (Sturnus vulgaris; Chapter 5). The proportion of male offspring significantly increases in barn swallow colonies surrounded by large extent of hayfields, the main foraging habitat for this insectivorous bird, and, only in second broods, in colonies showing recent negative demographic trends. These findings suggest an adaptive sex allocation strategy by parents, because males have a higher natal philopatry than females and are thus more likely to benefit from favourable local environment (Chapter 4). I have also documented a seasonal decline in offspring quality (e.g. reduction of antioxidant defence and body growth), particularly marked for females, in the common starling. Such a sexual-related decrease in condition is accompanied by a female-biased mortality in the late-hatched broods and it is possibly caused by a skew of parental food allocation towards higher-quality males or by the monopolization of resources by stronger male competitors (Chapter 5). Finally, in the last part of my work (Chapters 6-7) I have considered the carry-over effects of rearing conditions on longevity and reproductive success in the barn swallow. More specifically, I have shown that conditions experienced at the nestlings stage are important determinants of lifetime fitness: indeed, hatching date and individual condition (e.g. stronger immune response and larger body size compared to nest mates) predict lifespan and the number of offspring successfully reared during the entire life (Chapter 6). Moreover, I found that a bacterial immune challenge during the early post-natal stage, may cause the failure of the first breeding attempt, thus considerably reducing reproductive success in this short-lived species (Chapter 7). In conclusion, the present work provides novel information on the function of begging displays performed both in the presence or in the absence of parents, and the ultimate role of begging behaviour in the resolution of intra-familiar conflicts. It further provides new evidence for the relevance of the rearing environment, mediated by parental decisions over breeding, in affecting nestling growth and reproductive value, potentially causing long-term effects on survival and reproduction, and in determining the parental sex allocation strategies.

In nature, environments are often variable and heterogeneous influencing ecological and evolutionary processes. This thesis focus on how animals interact with their environment and how that affects the reproductive decisions they make. Using empirical data collected from wild collared flycatcher populations, experiments and molecular approaches I try to unveil some of these relationships and the evolutionary, ecological and conservation implications of these findings are discussed. Firstly, collared flycatchers were shown to use breeding densities of their own and other species using similar resources when assessing costs and benefits associated to breeding in specific habitats. However, species will vary in how informative they are, and the worst competitor – with whom you overlap most in resources needs – also provides the best source of information. Collared flycatcher parents will also benefit differentially from investments in sons and daughters due to habitat characteristics and dispersal differences between the sexes. Here, I show that they will produce more of the sex that will give the highest expected fitness return given the environment they are in. These results also provide a reciprocal scenario to Clark's (1978) classical study of sex ratio adjustment in relation to local resource competition (LRC), as more of the natal philopatric sex is produced when LRC is low. Secondly, the effect of elaborated ornaments on paternity in the socially monogamous collared flycatcher was shown to be of more importance in areas where the intensity of intra- and intersexual conflicts are expected to be elevated. Hence, ornamentation by environmental interactions determines paternity, illustrating that sexual selection through extra-pair paternity is context dependent. Finally, even though the collared flycatcher populations that this thesis is based on have been studied on their breeding grounds for more then 25 years, we know little of where they are when they are not breeding. Here, stable isotope signatures in winter-grown feathers suggests that they may spend their winter with their breeding ground neighbours and do so repeatedly over years. Differences between breeding populations at this small scale should have many impactions for evolutionary and ecological processes as it will, for example, determine with whom individuals interact throughout their life.

Aim: Preferential treatment and allocation of quotes according to sex are two current concepts due to the increasing demand for equality. One organization that may use preferential treatment is the fire department. This is why we chose it as a starting point for our study. The aim with this essay is to investigate how Gästrike Räddningstjänst can create a more equal organization.

Method: We have interviewed eight employees and prepared questions for each one. This represents a qualitative method. We have studied literature on the subject to get a theoretical background before the interviews. After the study we analysed the interviews with help from the theory. And finally we drew conclusions from this analysis. This resulted in suggestions that could help Gästrike Räddningstjänst create a more equal organization.

Result & Conclusions: Equality between the sexes is important but at the same time it is important that the employed women have the right qualities. Measures should be taken to draw women to the profession in order to create a wider selection. One measure that could give a wider selection is positive special treatment. It is important to think about the employees while making a change so that negative attitudes do not affect the process to make the profession more equal. Based on theory we can see that it is important to communicate the aim of the change to reduce resistance from the employees. Change has to be allowed to take time since the organizational culture is strong and has existed for a long time. Due to the strong culture it is necessary to focus on measures that will create a strong but adaptable culture. Management should continually evaluate the process of change to discover possible problems and to highlight progress. Employees can also take part in the evaluation.

Suggestions for future research: It would be interesting to compare different fire departments in Sweden considering their work with equality between sexes. It would also be interesting to observe the process of recruitment more closely.

Contribution of the thesis: Our hope is that this essay helps to increase awareness in the important issue of equality.

Syfte: Positiv särbehandling och kvotering är två aktuella begrepp i och med ökade krav på jämställdhet. Räddningstjänsten är en organisation som berörs av framförallt positiv särbehandling. Därför valde vi brandmannayrket som utgångspunkt för vår studie. Syftet med denna uppsats är att undersöka hur ledningen inom Gästrike Räddningstjänst kan gå tillväga för att skapa en mer jämställd organisation.

Metod: Vi har intervjuat åtta personer och förberett anpassade frågor till var och en, vilket representerar en kvalitativ metod. Innan intervjuerna genomförde vi en litteraturstudie för att få en teoretisk grund. Efter vår empiriska studie analyserade vi intervjuerna med stöd av teorin. Därefter drog vi slutsatser utifrån analysen, vilket resulterade i förslag på hur Gästrike Räddningstjänst kan skapa en mer jämställd organisation.

Resultat & slutsats: Jämställdhet är viktigt men samtidigt måste de kvinnor som anställs vara tillräckligt kompetenta. Åtgärder bör vidtas för att locka fler kvinnor till yrket för att skapa ett bredare urval vid rekrytering. En åtgärd som kan ge ett bredare urval är positiv särbehandling. Vid förändringsarbetet är det viktigt att ta hänsyn till anställda så att inte negativa attityder försvårar processen att göra yrket mer jämställt. Utifrån teorin kan vi se att det är viktigt att tydligt kommunicera syftet med förändringen för att minska ett eventuellt motstånd. Förändringsarbetet måste få ta tid eftersom det är en stark organisationskultur som funnits länge. På grund av den starka organisationskulturen är det nödvändigt att fokusera på faktorer som gör kulturen stark men anpassningsbar. För att upptäcka eventuella problem och för att belysa framsteg bör ledning kontinuerligt följa upp förändringsarbetet. Detta kan med fördel genomföras tillsammans med de anställda.

Förslag till fortsatt forskning: Det skulle vara intressant att jämföra olika brandstationer i Sverige för att se om det ser likadant ut i hela landet, eller om vissa stationer kommit längre i sitt jämställdhetsarbete. Det skulle även vara intressant att mer närgående observera anställningsprocessen.

Sexually selected ornaments are among the most spectacular traits in nature. Indeed, the extreme costs associated with producing sexual traits seem to play a crucial role in their evolution by enforcing honest levels of advertisement: only males with high levels of acquired resources (or high ‘condition’, as it is known in the literature) can afford to produce extravagant signals, a phenomenon which maintains signal reliability in a constant environment. In my thesis I examine many implications of this condition-dependent model of ornament and preference evolution for variation in age-dependent allocation to sexual signals and other life history traits. In Chapter 1, I review theoretical implications of condition-dependent signalling for life history and sexual selection theory. I note that a universal cost of expenditure in sexual advertisement is metabolic in nature: metabolites used to fund ornament expression are by definition unavailable to other life history traits that compete for a limited resource pool. This universal constraint on expenditure does more than maintain honesty (as noted above), however: the reliance of sexual displays on high levels of nutrient acquisition may help maintain genetic variation in sexual signals that would otherwise be eroded by strong mate choice, and without which the selective basis for good-genes choice would disappear. Three mechanisms in particular probably help to maintain genetic variation in acquisition. 1) Because acquiring resources and converting them efficiently to useful forms depends on the high function of many biochemical pathways, condition is undoubtedly highly polygenic, which slows the erosion of genetic variation under strong directional selection by females (especially in the presence of epistatic interactions). 2) The highly polygenic nature of condition also presents a large target for mutation, which continually restores variation at the loci under selection. 3) The many loci underlying condition may also be particularly sensitive to environmental heterogeneity in time or space. By favouring the most ornate males, females acquire high performing genes for their offspring, regardless of the precise allele combinations that have conferred the ability to acquire resources. Selection on specific alleles is liable to fluctuate over time or space whenever allelic performance is strongly context-specific. I close by noting the considerable challenges in advancing research on sexual selection and life history allocation, including the fact that two key processes central to life history (acquisition and allocation) are latent variables that interact in complexways and are intrinsically difficult to measure empirically. In the remainder of my thesis I conduct a series of experiments involving decorated crickets, Gryllodes sigillatus, which are useful models for studying life history because they enable precise measurement of male reproductive effort. Male G. sigillatus face important allocation decisions owing to the highly polyandrous nature of females, and the substantial costs involved in signalling and mating. Chapter 2 examines sex differences in age-dependent reproductive effort as a function of diet and development stage. I reared outbred crickets using four combinations of diet nutritional quality, and studied the effects of these combinations on male and female reproductive effort (calling effort in males and fecundity in females) and longevity. While I expected males to be more sensitive than females to variation in diet and developmental changes in its quality, I actually observed the opposite: males in all treatments increased calling effort over time, exhibiting consistently positive covariance between calling effort and longevity across treatments. By contrast, the relationships between female reproductive effort and longevity changed dramatically across treatments, and females who lived to intermediate ages had the highest fecundity. Although my results support sex-specific selection on life history allocation over time, a compelling additional explanation for my findings relates to the strategic role of calling for achieving male fitness. In the absence of positive feedback from potential mates, perhaps male allocation to sexual advertisement is careful and only increases gradually as a function of accumulating metabolic resources and increasing risk of intrinsic mortality. Alleles underlying condition are expected to be particularly sensitive to environmental heterogeneity. While this sensitivity may help maintain additive variation in male quality (which is essential for the sustenance of adaptive good-genes mate choice, as noted in Chapter 1), too much environmental sensitivity could also underiii mine the signal value of the male trait. For example, if there are strong genotypeby- environment interactions (GEIs) for sexual advertisement, in a rapidly changing environment females risk favouring a male whose alleles are no longer best suited to current conditions. This problem is particularly pressing for animals like crickets where males exhibit a behaviourally plastic sexual display (such as calling), and so may dynamically adjust signalling effort over time. In Chapter 3, I used inbred lines of decorated crickets to quantify age and diet dependent genetic variation in male signalling. I demonstrate that while genetic correlations across diets were quite strong for morphological traits, correlations between measures of the male sexual trait rapidly approached zero as I increased the distance in time (i.e., across widely spaced ages) or diet (i.e., comparing more dissimilar dietary histories) between samples. While extrapolating from my laboratory experiments to nature is difficult, my findings nevertheless cast doubt on the value of behaviourally dynamic signals (such as cricket calls) for reliably indicating genetic quality in realistically complex environments. In Chapter 4 I used physiological assays to evaluate factors affecting metabolite storage and use over time in decorated crickets. I manipulated the acquisition ability of all males using artificial diets that varied linearly in nutrient quality, and manipulated access to female mates over the course of the second week of adult life. By sacrificing crickets at key stages before and after manipulating the diet and social environment, I was able to estimate changes in stored metabolites, and relate these changes to calling effort and longevity. During the first week of adulthood (in the absence of females), higher diet quality significantly increased calling effort and storage of lipid, glycogen, and carbohydrate (but not protein). The presence of females increased both the probability of calling and the amount of calling during the second week, whereas diet quality only improved calling effort. By the end of the second week, calling effort had decreased, even by high quality males in the presence of females, suggesting a depletion of resources. Furthermore, the loss of condition during week 2 covaried with calling effort during the previous week irrespective of diet. Males who started the second week in high condition lost more glycogen and carbohydrate than rivals; meanwhile, lipid accumulation covaried positively with calling effort during week 2. The contrasting patterns of storage and use for lipids compared to the ‘quick-release’ metabolites (glycogen and carbohydrates) affirms starkly distinct functions for the different storage components, and underlines the importance of specific physiological measures in life history research. Finally, in the general discussion, I attempt to synthesise my thesis’s contributions to the study of life history trade-offs involving behavioural sexual displays.

The goal of this paper is to benchmark Answer Set Programming (ASP) systems to test their performance when dealing with a complex optimization problem. In particular, the problem tackled is resource allocation in the area of Business Process Management (BPM). Like many other scheduling problems, the allocation of resources and starting times to business process activities is a challenging optimization problem for ASP solvers. Our problem encoding is ASP Core-2 standard compliant and it is realized in a declarative and compact fashion. We develop an instance generator that produces problem instances of different size and hardness with respect to adjustable parameters. By using the baseline encoding and the instance generator, we provide a comparison between the two award-winning ASP solvers clasp and wasp and report the grounding performance of gringo and i-dlv. The benchmark suggests that there is room for improvement concerning both the grounders and the solvers. Fostered by the relevance of the problem addressed, of which several variants have been described in different domains, we believe this is a solid application-oriented benchmark for the ASP community.
Series: Working Papers on Information Systems, Information Business and Operations

La tesi affronta il problema dell'allocazione del capitale. Dopo una breve rassegna della letteratura e dei metodi standard, vengono considerati i problemi di allocazione del capitale rispetto ad una particolare classe di misure di rischio, ovvero quelle di Haezendonck-Goovaerts (HG) [13, 46]. Per prima cosa, generalizziamo la regola di allocazione del capitale (CAR) introdotta da Xun et al. [66] per i premi al rischio di Orlicz [47], utilizzando due diversi approcci, al fine di coprire le misure di rischio di HG. Forniamo poi versioni robuste delle CAR introdotte, sia considerando il caso dell’ambiguità sul modello probabilistico che quello di una molteplicità di funzioni di Young, seguendo lo schema di [12]. Successivamente, introduciamo un nuovo approccio per affrontare i problemi di allocazione del capitale dal punto di vista degli insiemi di accettazione, definendo il concetto di famiglia di insiemi di sotto-accettazione. Studiamo le relazioni tra le nozioni di sotto-accettabilità e accettabilità di una posizione rischiosa e il loro impatto sull'allocazione del capitale. Definiamo la nozione di regola di contributo al rischio e mostriamo come in questo contesto sia interpretabile come uno strumento per valutare il contributo di un sotto-portafoglio a un dato portafoglio, in termini di accettabilità, senza necessariamente coinvolgere una misura di rischio. Inoltre, indaghiamo per quali condizioni, su una regola di contributo al rischio, vale una rappresentazione in termini di insiemi di accettazione della regola di contributo al rischio stessa, estendendo così a questa contesto l'interpretazione, classica nella teoria delle misure di rischio, di importo monetario minimo richiesto per rendere una posizione accettabile. Infine, discutiamo alcune ulteriori estensioni del problema dell'allocazione del capitale. In particolare, discutiamo la possibilità di estendere quest'ultimo al contesto delle misure di rischio intrinseco [36]. In primo luogo, rivediamo brevemente le nozioni e i risultati principali sulle misure di rischio intrinseco, fornendo un confronto con quelle tradizionali. Successivamente, discutiamo l'idoneità del problema dell'allocazione del capitale in questo contesto, così come quello delle proprietà da richiedere alle regole di allocazione del capitale, considerando sia l’approccio standard che quello basato sugli insiemi di accettazione. Deriviamo risultati simili al caso delle misure di rischio tradizionali.
The thesis deals with the problem of capital allocation. After a brief review of the literature and of the standard methods, capital allocation problems with respect to a particular class of risk measures, namely the Haezendonck-Goovaerts (HG) ones [13, 46], are considered. We first generalize the capital allocation rule (CAR) introduced by Xun et al. [66] for Orlicz risk premia [47], using two different approaches, in order to cover HG risk measures. We then provide robust versions of the introduced CARs, both considering the case of ambiguity over the probabilistic model and the one of multiple Young functions, following the scheme of [12]. Further on, we introduce a new approach to face capital allocation problems from the perspective of acceptance sets, by defining the family of sub-acceptance sets. We study the relations between the notions of sub-acceptability and acceptability of a risky position and their impact on the allocation of risk. We define the notion of risk contribution rule and show how in this context it is interpretable as a tool for assessing the contribution of a sub-portfolio to a given portfolio, in terms of acceptability, without necessarily involving a risk measure. Furthermore, we investigate under which conditions on a risk contribution rule a representation of an acceptance set holds in terms of the risk contribution rule itself, thus extending to this setting the interpretation, classical in risk measures theory, of minimal amount required to hedge a risky position. Finally, we provide a discussion on some possible further extensions of the capital allocation problem. In particular, we discuss the possibility of extending the latter to the framework of intrinsic risk measures [36]. We briefly review the notions and results on intrinsic risk measures, providing a comparison with traditional ones. We later discuss the suitability of the capital allocation problem in this context, as well as that of the properties related to capital allocation rules, considering both the standard setting and the one based on acceptance sets. We derive some results similar to the case of traditional risk measures.

Thesis (Ph. D.)--Ohio State University, 2004.
Title from first page of PDF file. Document formatted into pages; contains xiii, 109 p.; also includes graphics Includes bibliographical references (p. 99-102). Available online via OhioLINK's ETD Center

FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico
Ericsson Brasil
Uma nova geraÃÃo de sistemas de comunicaÃÃes sem fio, 5a GeraÃÃo (5G), à prevista para 2020. Para a 5G, à esperado o surgimento de diversos serviÃos baseados em comunicaÃÃes mÃquina à mÃquina em diferentes Ãreas, como assistÃncia mÃdica, seguranÃa e redes de mediÃÃo inteligente. Cada um com diferentes requerimentos de taxa de transmissÃo, latÃncia, capacidade de processamento, eficiÃncia energÃtica, etc. Independente do serviÃo, os clientes precisam ficar satisfeitos. Isto està impondo uma mudanÃa de paradigmas em direÃÃo à priorizaÃÃo do usuÃrio como fator mais importante no gerenciamento de redes sem fio. Com esta mudanÃa, criou-se o conceito de qualidade de experiÃncia (do inglÃs, Quality of Experience (QoE)), que descreve de forma subjetiva como o serviÃo à percebido pelo usuÃrio. A QoE normalmente à avaliada por uma nota entre 1 e 5, chamada nota mÃdia de opiniÃo (do inglÃs, Mean Opinion Score (MOS)). Neste contexto, conceitos de QoE podem ser considerados com diferentes objetivos, como: aumentar a vida Ãtil de baterias, melhorar a seleÃÃo para acesso à rede e aprimorar a alocaÃÃo dos recursos de rÃdio (do inglÃs, Radio Resource Allocation (RRA)). Com relaÃÃo à RRA, nesta dissertaÃÃo consideram-se requerimentos de QoE na gestÃo dos recursos disponÃveis em um sistema de comunicaÃÃes sem fio, como espectro de frequÃncia e potÃncia de transmissÃo. Mais especificamente, estuda-se um problema de assinalamento de recursos de rÃdio e de alocaÃÃo de potÃncia que objetiva maximizar a mÃnima MOS do sistema sujeito a satisfazer um nÃmero mÃnimo de usuÃrios prÃ-estabelecido. Inicialmente, formula-se um novo problema de otimizaÃÃo considerando restriÃÃes quanto à potÃncia de transmissÃo e quanto à fraÃÃo de usuÃrios que deve ser satisfeita, o que à um importante tÃpico do ponto de vista das operadoras. Este à um problema nÃo linear e de difÃcil soluÃÃo. Ele à entÃo reformulado como um problema linear inteiro e misto, que pode ser resolvido de forma Ãtima usando algoritmos conhecidos de otimizaÃÃo. Devido à complexidade da soluÃÃo Ãtima obtida, propÃe-se uma heurÃstica chamada em inglÃs de Power and Resource Allocation Based on Quality of Experience (PRABE). O mÃtodo proposto à avaliado por meio de simulaÃÃes e os resultados obtidos mostram que sua performance à superior à de outros existentes, sendo prÃxima à da Ãtima.
A new generation of wireless networks, the 5th Generation (5G), is predicted for beyond 2020. For the 5G, it is foreseen an emerging huge number of services based on Machine-Type Communications (MTCs) in different fields, such as, health care, smart metering and security. Each one of them requiring different throughput rates, latency, processing capacity, energy efficiency, etc. Independently of the service type, the customers still need to get satisfied, which is imposing a shift of paradigm towards incorporating the user as the most important factor in wireless network management. This shift of paradigm drove the creation of the Quality of Experience (QoE) concept, which describes the service quality subjectively perceived by the users. QoE is generally evaluated by a Mean Opinion Score (MOS) ranging from 1 to 5. In this context, QoE concepts can be considered with different objectives, such as, increasing battery life, optimizing handover decision, enhancing access network selection and improving Radio Resource Allocation (RRA). Regarding the RRA, in this masterâs thesis we consider QoE requirements when managing the limited available resources of a communication system, such as frequency spectrum and transmit power. More specifically, we study a radio resource assignment and power allocation problem that aims at maximizing the minimum MOS of the users in a system subject to attaining a minimum number of satisfied users. Initially, we formulate a new optimization problem taking into account constraints on the total transmit power and on the fraction of users that must be satisfied, which is an important topic from an operatorâs point of view. The referred problem is non-linear and hard to solve. However, we get to transform it into a simpler form, a Mixed Integer Linear Problem (MILP), that can be optimally solved using standard numerical optimization methods. Due to the complexity of obtaining the optimal solution, we propose a heuristic solution to this problem, called Power and Resource Allocation Based on Quality of Experience (PRABE). We evaluate the proposed method by means of simulations and the obtained results show that it outperforms some existing algorithms, as well as it performs close to the optimal solution.

Doutoramento em Engenharia Electrotécnica
Na última década tem-se assistido a um crescimento exponencial das redes de comunicações sem fios, nomeadamente no que se refere a taxa de penetração do serviço prestado e na implementação de novas infra-estruturas em todo o globo. É ponto assente neste momento que esta tendência irá não só continuar como se fortalecer devido à convergência que é esperada entre as redes móveis sem fio e a disponibilização de serviços de banda larga para a rede Internet fixa, numa evolução para um paradigma de uma arquitectura integrada e baseada em serviços e aplicações IP. Por este motivo, as comunicações móveis sem fios irão ter um papel fundamental no desenvolvimento da sociedade de informação a médio e longo prazos. A estratégia seguida no projecto e implementação das redes móveis celulares da actual geração (2G e 3G) foi a da estratificação da sua arquitectura protocolar numa estrutura modular em camadas estanques, onde cada camada do modelo é responsável pela implementação de um conjunto de funcionalidades. Neste modelo a comunicação dá-se apenas entre camadas adjacentes através de primitivas de comunicação pré-estabelecidas. Este modelo de arquitectura resulta numa mais fácil implementação e introdução de novas funcionalidades na rede. Entretanto, o facto das camadas inferiores do modelo protocolar não utilizarem informação disponibilizada pelas camadas superiores, e vice-versa acarreta uma degradação no desempenho do sistema. Este paradigma é particularmente importante quando sistemas de antenas múltiplas são implementados (sistemas MIMO). Sistemas de antenas múltiplas introduzem um grau adicional de liberdade no que respeita a atribuição de recursos rádio: o domínio espacial. Contrariamente a atribuição de recursos no domínio do tempo e da frequência, no domínio espacial os recursos rádio mapeados no domínio espacial não podem ser assumidos como sendo completamente ortogonais, devido a interferência resultante do facto de vários terminais transmitirem no mesmo canal e/ou slots temporais mas em feixes espaciais diferentes. Sendo assim, a disponibilidade de informação relativa ao estado dos recursos rádio às camadas superiores do modelo protocolar é de fundamental importância na satisfação dos critérios de qualidade de serviço exigidos. Uma forma eficiente de gestão dos recursos rádio exige a implementação de algoritmos de agendamento de pacotes de baixo grau de complexidade, que definem os níveis de prioridade no acesso a esses recursos por base dos utilizadores com base na informação disponibilizada quer pelas camadas inferiores quer pelas camadas superiores do modelo. Este novo paradigma de comunicação, designado por cross-layer resulta na maximização da capacidade de transporte de dados por parte do canal rádio móvel, bem como a satisfação dos requisitos de qualidade de serviço derivados a partir da camada de aplicação do modelo. Na sua elaboração, procurou-se que o standard IEEE 802.16e, conhecido por Mobile WiMAX respeitasse as especificações associadas aos sistemas móveis celulares de quarta geração. A arquitectura escalonável, o baixo custo de implementação e as elevadas taxas de transmissão de dados resultam num processo de multiplexagem de dados e valores baixos no atraso decorrente da transmissão de pacotes, os quais são atributos fundamentais para a disponibilização de serviços de banda larga. Da mesma forma a comunicação orientada à comutação de pacotes, inenente na camada de acesso ao meio, é totalmente compatível com as exigências em termos da qualidade de serviço dessas aplicações. Sendo assim, o Mobile WiMAX parece satisfazer os requisitos exigentes das redes móveis de quarta geração. Nesta tese procede-se à investigação, projecto e implementação de algoritmos de encaminhamento de pacotes tendo em vista a eficiente gestão do conjunto de recursos rádio nos domínios do tempo, frequência e espacial das redes móveis celulares, tendo como caso prático as redes móveis celulares suportadas no standard IEEE802.16e. Os algoritmos propostos combinam métricas provenientes da camada física bem como os requisitos de qualidade de serviço das camadas superiores, de acordo com a arquitectura de redes baseadas no paradigma do cross-layer. O desempenho desses algoritmos é analisado a partir de simulações efectuadas por um simulador de sistema, numa plataforma que implementa as camadas física e de acesso ao meio do standard IEEE802.16e.
In the last decade mobile wireless communications have witnessed an explosive growth in the user’s penetration rate and their widespread deployment around the globe. It is expected that this tendency will continue to increase with the convergence of fixed Internet wired networks with mobile ones and with the evolution to the full IP architecture paradigm. Therefore mobile wireless communications will be of paramount importance on the development of the information society of the near future. In particular a research topic of particular relevance in telecommunications nowadays is related to the design and implementation of mobile communication systems of 4th generation. 4G networks will be characterized by the support of multiple radio access technologies in a core network fully compliant with the Internet Protocol (all IP paradigm). Such networks will sustain the stringent quality of service (QoS) requirements and the expected high data rates from the type of multimedia applications to be available in the near future. The approach followed in the design and implementation of the mobile wireless networks of current generation (2G and 3G) has been the stratification of the architecture into a communication protocol model composed by a set of layers, in which each one encompasses some set of functionalities. In such protocol layered model, communications is only allowed between adjacent layers and through specific interface service points. This modular concept eases the implementation of new functionalities as the behaviour of each layer in the protocol stack is not affected by the others. However, the fact that lower layers in the protocol stack model do not utilize information available from upper layers, and vice versa, downgrades the performance achieved. This is particularly relevant if multiple antenna systems, in a MIMO (Multiple Input Multiple Output) configuration, are implemented. MIMO schemes introduce another degree of freedom for radio resource allocation: the space domain. Contrary to the time and frequency domains, radio resources mapped into the spatial domain cannot be assumed as completely orthogonal, due to the amount of interference resulting from users transmitting in the same frequency sub-channel and/or time slots but in different spatial beams. Therefore, the availability of information regarding the state of radio resources, from lower to upper layers, is of fundamental importance in the prosecution of the levels of QoS expected from those multimedia applications. In order to match applications requirements and the constraints of the mobile radio channel, in the last few years researches have proposed a new paradigm for the layered architecture for communications: the cross-layer design framework. In a general way, the cross-layer design paradigm refers to a protocol design in which the dependence between protocol layers is actively exploited, by breaking out the stringent rules which restrict the communication only between adjacent layers in the original reference model, and allowing direct interaction among different layers of the stack. An efficient management of the set of available radio resources demand for the implementation of efficient and low complexity packet schedulers which prioritize user’s transmissions according to inputs provided from lower as well as upper layers in the protocol stack, fully compliant with the cross-layer design paradigm. Specifically, efficiently designed packet schedulers for 4G networks should result in the maximization of the capacity available, through the consideration of the limitations imposed by the mobile radio channel and comply with the set of QoS requirements from the application layer. IEEE 802.16e standard, also named as Mobile WiMAX, seems to comply with the specifications of 4G mobile networks. The scalable architecture, low cost implementation and high data throughput, enable efficient data multiplexing and low data latency, which are attributes essential to enable broadband data services. Also, the connection oriented approach of Its medium access layer is fully compliant with the quality of service demands from such applications. Therefore, Mobile WiMAX seems to be a promising 4G mobile wireless networks candidate. In this thesis it is proposed the investigation, design and implementation of packet scheduling algorithms for the efficient management of the set of available radio resources, in time, frequency and spatial domains of the Mobile WiMAX networks. The proposed algorithms combine input metrics from physical layer and QoS requirements from upper layers, according to the crosslayer design paradigm. Proposed schedulers are evaluated by means of system level simulations, conducted in a system level simulation platform implementing the physical and medium access control layers of the IEEE802.16e standard.

Neste trabalho são investigados problemas de alocação de espetro e potência em redes sem fio de múltiplo acesso e propostas sete soluções distintas para diferentes cenários e topologias que serão enumeradas a seguir. Primeiramente o problema de maximização da eficiência energética em redes cooperativas do tipo multiportadora com múltiplo acesso por divisão de código de sequência direta é abordado e as seguintes soluções são apresentadas: duas abordagens na perspectiva de teoria de jogos, uma utilizando algoritmo de water-filling (1) e outra utilizando o algoritmo distribuído de controle de potência baseado no equilíbrio de Verhulst (2), uma terceira solução também inspirado no último algoritmo citado e na média dos coeficientes de canal das subportadoras do sistema (3); uma abordagem heurística utilizando o algoritmo dos vaga-lumes (4) e outra utilizando a otimização por enxame de partículas (5). Em segundo lugar, foram investigados problemas de otimização em sistemas de múltiplo acesso por divisão ortogonal de frequência com provisão de qualidade de serviço estatística. Nesta segunda topologia dois problemas distintos foram analisados: o primeiro problema de maximização da capacidade efetiva do sistema foi solucionado utilizando o método de decomposição dual de Lagrange (6), o segundo problema cujo objetivo é a maximização da eficiência energética efetiva foi investigado e um solução baseada na combinação do método de Dinkelba e da decomposição dual de Lagrange foi proposta (7). Simulações computacionais foram conduzidas tendo em vista averiguar o desempenho das abordagens propostas e, quando possível, tais resultados numéricos foram comparados àqueles obtidos a partir de algoritmos alternativos existentes na literatura.
This work investigates the spectrum and power allocation problems in wireless multiple access networks and seven dfferent solutions to different scenarios and topologies, which are enumerated as follows. Three distinct solutions are presented to the energy effiency maximization problem in multicarrier direct sequence code division multiple acess cooperative: two game theoretic approaches, one using the iterative water-filling algorithm (1) and another one using the distributed power control algorithm based on Verhulst equilibrium concept (2), and a third solution also based on the last algorithm but considering the average channel power gain (3); an heuristic approach using the firefly algorithm (4) and the particle swarm optimization algorithm (5). In orthogonal frequency division multiple acess networks, optimization problems considering a statistical quality of service metric were analyzed: the first one is the effective capacity maximization which was solved through Lagrange dual decomposition method (6). The second one, in which the objective is to maximize the effective energy effiency was addressed and solution based on the Dinkelba method and further application of Lagrange dual decomposition was developed (7). Simulations were conducted to verify the proposed approaches performance and, whenever possible, the numerical results were compared to previous solution proposed in the literature.