11 resultados para mating choice
em Helda - Digital Repository of University of Helsinki
Resumo:
The results presented in this thesis show that all females of a given population do not necessarily choose similar mating partners. Specifically, partner preferences of a fish, the sand goby (Pomatoschistus minutus), varied among individual females and depended on the social context at the time of choice. I also show that females assess multiple mate choice cues simultaneously; partner preferences were based more strongly on an interaction effect between different choice cues than on any individual cue. Furthermore, I found that preferred matings involved fitness benefits in the form of increased offspring success, but these benefits were not significantly affected by mate compatibility. Hence, mate choice for partner compatibility does not appear to be an important determinant of the observed variation in female mate preferences in this species. The context-dependency of female mating preferences revealed is relevant to how genetic variation in sexually selected traits might be maintained: as the mating success of a certain male type varies according to the choice context, directional sexual selection on male traits is shown to be less intense than generally thought making for a slower loss of genetic variation in these traits. Mating preferences of sand gobies were assessed by giving females a binary choice between males that differed in body size and/or other focus traits. These association preferences were found to be sexually motivated, repeatable and to correspond to actual mating decisions.
Resumo:
The aim of this dissertation is to discuss the concept of choice in the most important collection of Islamic traditions, Sahih al-Bukhari. The author of the collection, Muhammad ibn Isma'il al-Bukhari, lived between 810-870. My starting point is the collection of texts as it is now in its normative, established form. I read the hadiths as pieces of reality, not as statements about reality. The historicity of the texts has no role at all in my analysis. Part I sketches out the hagiography of the life and work of the author and provides a short history of the development of hadith literature and the processes of collecting and classifying the texts are discussed briefly. Part one ends with the presentation of my way of using rhetorical analysis as a methodological tool. Part II introduces my analysis of the concept of choice. It is divided into ten chapters, each concentrating on one hadith cluster. Part II ends with a discussion of the philosophy of free will and predestination in early Islam. Hadith literature is often considered as a representative of predestinarian theology compared to the Qur'an which emphasises the reponsibility of people of their own acts. In my conclusions I suggest that accoding to the texts in Sahih al-Bukhari, people do deal with real choices in their lives. The collection includes both strictly predestinarian texts but it also compises texts which claim that people are demanded to make real choices, even choices concerning life and death.
Resumo:
Based on a one-year ethnographic study of a primary school in Finland with specialised classes in Finnish and English (referred to as bilingual classes by research participants), this research traces patterns of how nationed, raced, classed and gendered differences are produced and gain meaning in school. I examine several aspects of these differences: the ways the teachers and parents make sense of school and of school choice; the repertoires of self put forward by teachers, parents and pupils of the bilingual classes; and the insitutional and classroom practices in Sunny Lane School (pseudonym). My purpose is to examine how the construction of differentness is related to the policy of school choice. I approach this questions from a knowledge problematic, and explore connections and disjunctions between the interpretations of teachers and those of parents, as well as between what teachers and parents expressed or said and the practices they engaged in. My data consists of fieldnotes generated through a one-year period of ethnographic study in Sunny Lane School, and of ethnographic interviews with teachers and parents primarily of the bilingual classes. This data focuses on the initial stages of the bilingual classes, which included the application and testing processes for these classes, and on Grades 1─3. In my analysis, I pursue poststructural feminist theorisations on questions of knowledge, power and subjectivity, which foreground an understanding of the constitutive force of discourse and the performative, partial, and relational nature of knowledge. I begin by situating my ethnographic field in relation to wider developments, namely, the emergence of school choice and the rhetoric of curricular reform and language education in Finland. I move on from there to ask how teachers discuss the introduction of these specialised classes, then trace pupils paths to these classes, their parents goals related to school choice, teachers constructions of the pupils and parents of bilingual classes, and how these shape the ways in which school and classroom practices unfold. School choice, I argue, functioned as a spatial practice, defining who belongs in school and demarcating the position of teachers, parents and pupils in school. Notions of classed and ethnicised differences entered the ways teachers and parents made sense of school choice. Teachers idealised school in terms of social cohesiveness and constructed social cohesion as a task for school to perform. The hopes parents iterated were connected to ensuring their children s futurity, to their perceptions of the advantages of fluency in English, but also to the differences they believed to exist between the social milieus of different schools. Ideals such as openmindedness and cosmopolitanism were also articulated by parents, and these ideals assumed different content for ethnic majority and minority parents. Teachers discussed the introduction of bilingual classes as being a means to ensure the school s future, and emphasised bilingual classes as fitting into the rubric of Finnish comprehensive schooling which, they maintained, is committed to equality. Parents were expected to accommodate their views and adopt the position of the responsible, supportive parent that was suggested to them by teachers. Teachers assumed a posture teachers of appreciating different cultures, while maintaining Finnishness as common ground in school. Discussion on pupils knowledge and experience of other countries took place often in bilingual classes, and various cultural theme events were organized on occasion. In school, pupils are taught to identify themselves in terms of cultural belonging. The rhetoric promoted by teachers was one of inclusiveness, which was also applied to describe the task of qualifying pupils for bilingual classes, qualifying which pupils can belong. Bilingual classes were idealised as taking a neutral, impartial posture toward difference by ethnic majority teachers and parents, and the relationship of school choice to classed advantage, for example, was something teachers, as well as parents, preferred not to discuss. Pupils were addressed by teachers during lessons in ways that assumed self responsibility and diligence, and they assumed the discursive category of being good, competent pupils made available to them. While this allowed them to position themselves favourably in school, their participation in a bilingual class was marked by the pressure to succeed well in school.
Resumo:
Eutrophication of the Baltic Sea is a serious problem. This thesis estimates the benefit to Finns from reduced eutrophication in the Gulf of Finland, the most eutrophied part of the Baltic Sea, by applying the choice experiment method, which belongs to the family of stated preference methods. Because stated preference methods have been subject to criticism, e.g., due to their hypothetical survey context, this thesis contributes to the discussion by studying two anomalies that may lead to biased welfare estimates: respondent uncertainty and preference discontinuity. The former refers to the difficulty of stating one s preferences for an environmental good in a hypothetical context. The latter implies a departure from the continuity assumption of conventional consumer theory, which forms the basis for the method and the analysis. In the three essays of the thesis, discrete choice data are analyzed with the multinomial logit and mixed logit models. On average, Finns are willing to contribute to the water quality improvement. The probability for willingness increases with residential or recreational contact with the gulf, higher than average income, younger than average age, and the absence of dependent children in the household. On average, for Finns the relatively most important characteristic of water quality is water clarity followed by the desire for fewer occurrences of blue-green algae. For future nutrient reduction scenarios, the annual mean household willingness to pay estimates range from 271 to 448 and the aggregate welfare estimates for Finns range from 28 billion to 54 billion euros, depending on the model and the intensity of the reduction. Out of the respondents (N=726), 72.1% state in a follow-up question that they are either Certain or Quite certain about their answer when choosing the preferred alternative in the experiment. Based on the analysis of other follow-up questions and another sample (N=307), 10.4% of the respondents are identified as potentially having discontinuous preferences. In relation to both anomalies, the respondent- and questionnaire-specific variables are found among the underlying causes and a departure from standard analysis may improve the model fit and the efficiency of estimates, depending on the chosen modeling approach. The introduction of uncertainty about the future state of the Gulf increases the acceptance of the valuation scenario which may indicate an increased credibility of a proposed scenario. In conclusion, modeling preference heterogeneity is an essential part of the analysis of discrete choice data. The results regarding uncertainty in stating one s preferences and non-standard choice behavior are promising: accounting for these anomalies in the analysis may improve the precision of the estimates of benefit from reduced eutrophication in the Gulf of Finland.
Resumo:
In aquatic environments, endocrine disrupting chemicals (EDCs) that interfere with the endocrinology of males and females form a threat to the maintenance of populations. EDCs are a diverse group of natural and manmade chemicals that already at very low concentrations (at nanogram levels) can have severe effects on reproduction by individuals, e.g. complete sex reversal, feminisation of males, impaired reproduction even resulting in near extinction of populations. With regard to fish, despite the extensive literature on physiological effects of EDCs, very little is known about potential population-level effects. In this thesis, I examined how 17α-ethinyl estradiol (EE2), a synthetic estrogen used in oral contraceptive pills, affects the reproductive behaviour of a marine fish, the sand goby (Pomatoschistus minutus). The aims were fourfold. First, I investigated how exposure to EE2 affects courtship and parental care of sand goby males. Secondly, I looked at effects on the mating system and sexual selection. In the third study, I observed the effects of exposure in a social context where exposed males had to compete with non-exposed males for resources and mates. Finally, I studied the effects of exposure on male-male competition and male aggressive behaviour. This work revealed that EE2 exposure impairs the ability of males to acquire and defend a nest, as well as diminishes the attractiveness of males to females by decreasing their courtship and aggressive behaviour. These effects are harmful for a male whose reproductive success is determined by the ability to compete for limited resources and to attract mates. Furthermore, this thesis showed that selection on male size was relaxed after EE2 exposure and male size had a smaller effect on mating success. These effects can be of a profound nature as they interfere with sexual selection, and may in the long run lead to the loss of traits maintained through sexual selection. The thesis shows that an exposure to environmentally relevant levels of EE2 clearly reduces the chances of individuals to reproduce successfully. Furthermore, it strongly suggests that several types of biomarkers should be used to detect and assess the effects of EDC exposure because severe behavioural effects can sometimes be seen before effects are detectable at the molecular or morphometric level. Behavioural assays should be considered an important complementary tool for the standard ecotoxicological assays because observed behavioural changes have direct and negative effects on fitness, while the connection between changes in molecular expression and fitness may be less obvious.
Resumo:
Jordens ekologiska system undergår för tillfället stora förändringar pga. människans aktiviteter. Ett växande antal studier visar att dessa förändringar påverkar naturliga och sexuella urvalet och därmed evolutiva processer. Målet med detta arbete var att undersöka effekterna av omgivningsförändringar på sexuella urvalet genom att använda den ökade övergödningen inom storpiggen Gasterosteus aculeatus lekområden som modell system. Sexuella urvalet är en viktig evolutiv kraft med följder på populations- och artnivå (Kapitel 1). Avhandlingens olika delar fokuserar på övergödningens effekter på upptäckandet av partners, användningen av visuella- och doftsignaler i partnersval, och fördelningen av parningsframgången mellan bobyggande hanar. I Kapitel II och III simuleras hur grumlighet orsakad av fytoplankton påverkar hastigheten med vilken potentiella partners påträffas, genom effekter på synligheten. Resultaten visar att normala algblomningar i Östersjön har en måttlig effekt på finnandet av potentiella partners. Detta tyder på att algblomningarna troligen inte kommer att minska på selektiva parningen pga. ökade sökkostnader. I Kapitel IV visas att storspiggen ändrar relativa användningen av olika signaler när vattnets grumlighet ökar; visuella signaler minskar i betydelse medan doftsignaler ökar i betydelse. Samtidigt underlättas användandet av doftsignaler av ändringar i vattnets kemiska sammansättning då fotosyntesen intensifieras (Kapitel V). Lek i övergödda vatten kan ändå vara kostsamt både på individ- och populationsnivån, då parasiterade hanar, som troligen är dåligt genetiskt anpassade till sin miljö, lyckas få mer ägg i sina bon än friskare hanar som troligen är av högre genetisk kvalitet (Kapitel VI). Övergödningen påverkar således partnersval och konkurrensen om partners genom att påverka upptäckandet av potentiella partners, evalueringen av partners och fördelningen av partners inom lekområdena. De följder detta kan ha för evolutionen av sexuellt selekterad egenskaper och för populationers dynamik och livskraft är dock oklara. Avhandlingen visar på svårigheten att förutse följderna av omgivningsförändringar för sexuella urvalet och effekterna på individ och populationsnivå.
Resumo:
Publishers of academic journals can be seen as service providers to authors, in addition to the traditional role of providers of research results to readers. The purpose of this study was to analyse how author choices of journal in construction management are affected by quality and service perceptions. Seven journals were identified and for each 2006 article, one author e-mail address was extracted. A web based questionnaire was sent to 397 authors and 35% responded. It was found that there were three journals regularly followed by at least half the respondents. Most of the other four journals have scopes broader than construction management and receive lower scores for characteristics such as impact on researchers. No open access journals were included, and authors in the field of construction management rarely post openly accessible copies of their manuscripts or publications on the web. Author ranking of journals for their next submission is found to be related to general criteria such as academic status, circulation figures and ISI indexation.