L'investissement des adultes pour augmenter la survie des jeunes est souvent optimisé par une communication émise par les jeunes et informant les parents de leur niveau de besoin. Nous avons exploré dans cette thèse si les comportements des larves de fourmi pouvaient être des quémandes alimentaires telles que définies par les modèles de communication honnête. En effet, les fourmis, eusociales, possèdent un système de relations sociales et de coopérations qui diffère du modèle parental classiquement décrit. Nous avons donc testé chez la fourmi Ectatomma tuberculatum si les comportements des larves pouvaient refléter leur niveau de besoin et si les ouvrières apportaient la nourriture en fonction du signal comme prédit par les modèles. Nous montrons dans cette thèse que les mouvements émis par les larves ainsi qu'un composé chimique volatil larvaire pourraient tous deux intervenir et influencer l'apport alimentaire par les ouvrières. Les mouvements larvaires augmentent avec le stade de développement des larves et le composé chimique augmenterait avec le niveau d'affamement des larves. Les ouvrières, nourrices et fourrageuses, pourraient donc optimiser la répartition des ressources alimentaires de la colonie grâce à ces signaux ou indices des larves. Cependant, nous montrons aussi que plusieurs autres facteurs proximaux interviennent. Les mouvements larvaires font suite à des contacts fortuits avec les ouvrières, et l'organisation spatiale des ouvrières et des larves influencent les mouvements larvaires et le nourrissage. Des hypothèses alternatives ou complémentaires à la communication sont donc proposées. / Parental investment to increase survivability of the young is often optimised by signalling emitted by the young and informing the parents of their level of need. In this thesis, we explored whether the behaviour of ant larvae could be analysed as food solicitations as defined by honest communication models. Indeed, ants are highly social and their social relations differ from the social relation in parent-offspring systems which is usually analysed for food solicitations. We therefore tested, in the ant Ectatomma tuberculatum, whether behaviour of the larvae was correlated with the level of need and if workers provisioned larvae with food according to the intensity of the signal, as predicted by honest signalling models. We showed in this thesis that movements displayed by the larvae as well as a larval volatile emission could influence food provisioning by workers. Larval movements increase with larval developmental stage and volatile emission vary with nutritional state of the larvae. Nurse and forager workers could then optimise food resources allocation inside the nest thanks to signals or cues from the larvae. However, we also show that several other proximal factors are involved. Larval movements are not freely displayed but follow a contact with a worker, and spatial organisation of workers and larvae influences larval movements and food provisioning. Thus we propose alternative or complementary hypotheses to the communication hypothesis.

The purposes of this study were to determine and describe the roles of persons other than professional development staff in the solicitation of major gifts from private individuals for selected senior colleges and universities as perceived by senior development officers. The activities of four groups of nondevelopment staff, trustees, president/chancellor, private citizens, and nondevelopment staff/faculty, were examined through the four steps of the major gift solicitation process: identification and rating, cultivation, the in person solicitation, and the thank-you process following the gift. The population encompassed all accredited, degree granting four year colleges and universities in the United States which solicit major gifts from private individuals. The sample consisted of the 223 schools which had received one or more gifts of one million dollars or more from private individuals as reported in Giving USA. Philanthronin Digest, or The Chronicle of Higher Education, between January 1, 1985, and December 31, 1987. The research instrument was a mailed questionnaire which was sent to the Chief Development Officer of the 223 schools in the sample. Replies were received from 162 institutions, for a response rate of 72.7%. Examination of the results of this study indicated that the services of nondevelopment personnel were used in the major gift solicitation process at the vast majority of schools in the United States, that over half of the major gift dollars solicited were attributable to the efforts of these individuals, and that the president/chancel lor was the most important advocate for an institution's development program followed by the trustees, private citizens, and finally the nondevelopment staff/faculty. Further examination of the data revealed specific determinants which a senior development officer should, for different nondevelopment groups, weigh more or less heavily when deciding which individual(s) will have the greatest likelihood of being influential with major donor prospects.

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