Sexual conflict occurs when individuals of one sex express traits that reduce the fitness of their mates. Males of many species harass females to gain copulations, which benefits males by increasing the number of offspring they sire but imposes energetic and opportunity costs on the females they harass. This thesis examined the fitness costs of sexual harassment to females, the energetic costs of mating to males, and the factors influencing the intensity of male competition for mates in the western mosquitofish Gambusia affinis. I quantified male and female behavior, four female fitness components (number of offspring per female, embryo number, growth, and survival), and an index of male body condition in response to changes in operational sex ratio (experiment 1) and male and female density (experiment 2). I found that a strong, negative effect of female density on female fitness overwhelmed any potential costs of male harassment, suggesting that ecological interactions between females may play a larger role in determining female fitness than conflict between the sexes. Agonistic chases and displays between males increased as the operational sex ratio increased (became male-biased), while the number of copulations males attempted decreased. This inverse relationship suggests a tradeoff between interfering with other males and attempting additional copulations with females. Increases in chases between males were largely due to changes in female density, but not male density, suggesting that the availability of females determines whether males escalate contests with other males. In contrast, the number of displays between males depended varied with male density but did not female density. This difference between chases and displays is likely due to their difference in function; chases are performed to prevent other males from mating while displays are used to assess male competitors. I did not detect any energetic cost of mating to males.

Statistical mechanics has been applied to a wide range of systems in physics, biology, medicine and even anthropology. This theory has been recently used to model the complex biochemical processes of gene expression and regulation. In particular, genetic networks offer a large number of interesting phenomena, such as multistability and oscillatory behaviour, that can be modelled with statistical mechanics tools. In the first part of this thesis we introduce gene regulation, genetic switches, and the colonization of a spatially structured media. We also introduce statistical mechanics and some of its useful tools, such as the master equation and mean- field theories. We present simple examples that are both pedagogical and also set the basis for the study of more complicated scenarios. In the second part we consider the exclusive genetic switch, a fundamental example of genetic networks. In this system, two proteins compete to regulate each other's dynamics. We characterize the switch by solving the stationary state in different limits of the protein binding and unbinding rates. We perform a study of the bistability of the system by examining its probability distribution, and by applying information theory techniques. We then present several versions of a mean field theory that offers further information about the switch. Finally, we compute the stationary probability distribution with an exact perturbative approach in the unbinding parameter, obtaining a valid result for a wide range of parameters values. The techniques used for this calculation are successfully applied to other switches. The topic studied in the third part of the thesis is the propagation of a trait inside an expanding population. This trait may represent resistance to an antibiotic or being infected with a certain virus. Although our model accounts for different examples in the genetic context, it is also very useful for the general study of a trait propagating in a population. We compute the speed of expansion and the stationary population densities for the invasion of an established and an expanding population, finding non-trivial criteria for speed selection and interesting speed transitions. The obtained formulae for the different wave speeds show excellent agreement with the results provided by simulations. Moreover, we are able to obtain the value of the speeds through a detailed analysis of the populations, and establish the requirements for our equations to present speed transitions. We finally apply our model to the propagation in a position-dependent fitness landscape. In this situation, the growth rate or the maximum concentration depends on the position. The amplitudes and speeds of the waves are again successfully predicted in every case.

La sélection naturelle constitue un processus clé de l’adaptation des populations à leur environnement, favorisant les variants présentant les meilleures valeurs sélectives. Les champignons présentent généralement des traits biologiques (diversité des modes de reproduction, grandes tailles de populations, fortes capacités de dispersion, entre autres) qui favorisent leur adaptation à des environnements variés. La compréhension des mécanismes qui sous-tendent l’évolution de leurs populations sous les contraintes, naturelles et anthropiques, qu’elles subissent constituent donc un enjeu majeur pour la protection des plantes, en particulier dans le contexte actuel de durabilité des méthodes de lutte. Dans cette thèse, nous avons décrit la structure et la diversité des populations Botrytis cinerea à l’aide de marqueurs neutres et sélectionnés et d’un échantillonnage emboîté, et avons proposé des mécanismes pouvant expliquer les résultats observés. Puis nous avons analysé la réponse adaptative des populations de B. cinerea en Champagne, aux applications de fongicides. Premièrement, nous avons montré que la pourriture grise était causée par un complexe de deux espèces cryptiques, vivant en sympatrie sur des hôtes communs. De plus, les populations françaises de B. cinerea sont structurées en cinq dèmes, caractérisés par le système de culture (sélection directionnelle), la plante-hôte (adaptation écologique), et dans une moindre mesure, par la géographie. Sur vigne, nous avons mis en évidence une entité dont l’isolement génétique semble lié à un isolement temporel. Par ailleurs, nous avons montré que l’application de fongicides conduit à la sélection de phénotypes résistants spécifiquement à quasiment tous les modes d’action homologués, selon des proportions variant suivant les vignobles et les usages. Plus particulièrement, la résistance aux fongicides inhibiteurs de la succinate déshydrogénase (SDHI) est causée par au moins sept mutations affectant les gènes encodant la protéine cible de ces fongicides, déterminant ainsi une grande variété de phénotypes. Enfin, nous avons montré que les fongicides ne modifiaient pas la structure neutre des populations mais qu’ils pouvaient conduire à une perte de richesse allélique dans les populations traitées ainsi qu’à un équilibre sélection-migration détectable dans certaines situations sous forme de clines au loci sous pression de sélection contemporaine tels que ceux déterminant la résistance multidrogues. La modélisation de l’évolution des fréquences de résistance hivernale a permis d’estimer le coût de la résistance pour quatre loci déterminant la résistance aux fongicides. Cette thèse a permis d’appréhender le fonctionnement des populations de B. cinerea et de comprendre et quantifier partiellement les mécanismes sélectifs opérant in natura. Ces informations seront utilisées pour raisonner des stratégies anti-résistance adaptées localement et durables. / Natural selection is the most powerful force driving population adaptation to their environment, favoring the variants with the best fitness. Fungi generally exhibit biological traits (diversity of reproduction modes, large population sizes, and intense dispersion) that favor their adaptation to changing environments. Therefore, disentangling the mechanisms that explain their evolution under natural and anthropic constraints constitute a major challenge for plant protection, especially in the actual context of agriculture sustainability. In this thesis, we described Botrytis cinerea population structure and diversity, using neutral and selected markers and a hierarchical sampling, and proposed mechanisms that may explain these observations. We then analyzed the adaptive answer of this species towards fungicide applications. First, we showed that grey mold populations were caused by a complex of two cryptic species, living sympatrically on the same hosts. Second, B. cinerea populations are divided into five demes, according to the cropping system (directional selection), the host-plant (ecological adaptation), and to a lesser extent, by geography. On grapevine, we identified a specific populations exhibiting temporal isolation, as an evidence of extreme exploration of the viticultural conditions. Moreover, fungicide applications select resistance towards all unisite modes of action, with few exceptions, but at varying proportions according to vineyards and fungicide use. More specifically, resistance to succinate dehydrogenase inhibitors (SDHIs) is caused by at least seven mutations altering the target genes of these fungicides, and determines a large variety of phenotypes in the field. At last, we showed that fungicides did not shape population structure but that they could decrease allele richness in treated areas and lead to migration-selection equilibrium, detectable in some situation and for loci under contemporary selective pressures as clines. Modeling the evolution of resistance during winter allowed estimating fitness cost of four loci involved in contemporary fungicide resistance, such as multidrug resistance. As a conclusion, this thesis helped to understand how B. cinerea populations evolve and to detect and quantify selective mechanisms at work in natura. This information will be useful to deign sustainable and locally-adapted anti-resistance strategies.

This thesis deals with solving of the Rubik's cube. It describes the Rubik's cube and the famous methods for its composition. The main goal of this work is to propose an evelutionary method that for any configuration of blocks will lead to its composition. The theis describes the problem encoding, the proposed evelutionary algorithm and its proper configuration and deployment. The achieved results are commented on and compared with other known mehtods in conclusions.