Sexual conflict arises in biparental species because of the fitness payoffs of shifting the costs of care onto their partner. The negotiation model asserts that parents actively monitor their partner’s level of investment and adjust their own in response generally resulting in partial compensation when a member of the pair reduces their level of investment. The willingness of one parent to compensate for the other’s change is found to be widely variable. Habitat or resource quality available to pairs may explain such variation. It is predicted that the level of compensation by one partner will increase with decreasing resource quality. I tested this prediction with the biparental burying beetle, <i>Nicrophorus orbicollis</i>. Under natural conditions, burying beetles apply costly social immune molecules to carcasses of small vertebrates to preserve nutritional value for young. The goals of this research were (1) to determine if males immunologically compensate when females are immunologically handicapped; and (2) determine the impact of resource quality on compensation. Changes in lysozyme-like-activity (LLA) and phenoloxidase (PO) production in oral and anal secretions were used to quantify social immune investment. Pairs were provided a mouse carcass of one of three qualities: freshly thawed, aged for 3 days, or aged for 7 days. As expected, female LLA decreased once injected with lipopolysaccharide (LPS) irrespective of carcass quality. Injections caused significant down regulation of oral PO in females. Male LLA increased as the quality of carcasses decreased when paired with handicapped females. Males showed no changes in PO across treatments or carcass types. My results demonstrate that males compensate for a change in maternal investment and the level of compensation increases as resource quality decreases.

The climate affects animal populations through several processes. These processes includereproduction, phenology and the success of hunting. By influencing the phenology of species theclimate also affects the way species interact. If a climate-induced phenology change promotes abasal species to bud earlier in the spring for example, this will affect the links to other species inthe food web due to a time lag in the tropic levels above. This dependence, that a predator has tobeing synchronous to its prey, is called the match/mismatch hypothesis (MMH). Studies haveindicated that species higher up in the food web adapt slower than species lower in the food webwith shorter generation times (which creates a temporal mismatch).A climate-induced phenology change in basal species could therefore be expected to affect thedensities and extinction rates of species higher up in the food web.In this study a declining conversion efficiency for predators was used to model the effects ofclimate change on triangular food webs with three trophic levels. This was done by using ageneralized Lotka-Volterra model. The results indicate that, in a food web with three trophiclevels, the densities of herbivores and carnivores drops in response to an increased change ofclimate. The extinction rates of carnivores also increase rapidly in response to an increasedclimate change. / Klimatet påverkar djurpopulationer genom ett flertal processer. Dessa processer inkluderarreproduktion, fenologi och jaktframgång. Genom att påverka arters fenologi påverkar klimatet ävenhur arter interagerar med varandra. Om en klimatinducerad fenologiförändring stimulerar en basalart att knoppa tidigare på våren kommer det att påverka länkar till andra arter i näringsväven pågrund av en tidsförskjutning till andra trofinivåer. Detta beroende för ett rovdjur att varasynkroniserad med sitt byte kallas för match/mismatch-hypotesen (MMH). Studier har indikerat attarter högre upp i näringsväven anpassar sig långsammare än arter lägre ned i näringsväven medkortare generationstid. En klimatinducerad fenologiförändring i basala arter kan därför förväntaspåverka densiteten och utdöendehastigheten för arter högre upp i näringsväven. Studien använderen avtagande rekryteringsförmåga för att modellera klimatförändringars effekt på trianguläranäringsvävar med tre trofinivåer. För att göra detta har en generell Lotka-Volterra modell används.Från resultaten av den här studien dras också slutsatsen att, i en näringsväv med tre trofinivåer,densiteten av herbivorer och karnivorer avtar som svar på en ökad klimatförändring.Utdöendehastigheten för rovdjur ökar också snabbt som svar på en ökande klimatförändring.

No description available.

Cette thèse s'inscrit dans la littérature relative au problème d'arbitrage durée, coût et qualité en gestion de projet. Nous développons un modèle d'accélération des projets de fabrication par le recours au travail temporaire et aux heures supplémentaires. Nous prenons en compte l'impact de la main d'œuvre additionnelle sur la durée via les pertes de productivité et sur la qualité des activités qui composent le projet. La qualité de toute activité est mesurée par le pourcentage d'items validés dans sa check-list de contrôle qualité. Nous proposons une formulation linéaire du problème de minimisation de la durée du projet sous contrainte de budget et de respect d'un seuil de qualité minimum pour chacune des activités que le projet comporte. Le programme d'optimisation mixte qui en résulte est appliqué au cas d'un projet de fabrication d'une motrice TGV et permet d'obtenir une planification prévisionnelle de la main d'œuvre pour atteindre la durée optimale d'exécution. Le modèle peut également être utilisé pour accélérer un projet en cours d'exécution ou à des fins plus stratégiques de dimensionnement des postes de travail. / We address the discrete time resource-constrained project scheduling problem in which each activity has a specified work content and its resource usage may vary from period to period. We consider temporary work and overtime as additional renewable resources for crashing the project. We assume that the project quality may be affected by crashing as well as its completion time through productivity loss due to overmanning. We develop a Mixed-Integer Linear Programming (MILP) model to minimise the makespan subject to a budget constraint and to acceptable quality levels for all activities so as to avoid rework. The proposed approach is applied to an actual manufacturing project of a very high speed train motor coach.