In addition to habitat loss and fragmentation, habitat degradation can have important consequences for biodiversity and population persistence, including effects on ecological and genetic processes beyond decreased demographic viability and the loss of genetic variation. Particularly interesting is the potential for evolutionary changes and adaptation to degraded habitats, that can affect population viability even in the short-term. Here, I explore how environmental changes after habitat degradation affect the evolutionary dynamics of populations of the rainforest cycad Zamia fairchildiana, specifically how habitat degradation affects gene dispersal, inbreeding, directional selection, and genotype-by-environment interactions, and the potential for genetic differentiation between populations. Colonies of Z. fairchildiana showed little genetic differentiation in neutral molecular markers across study sites, thus can be considered as subpopulations. Subpopulations in the disturbed habitat are experiencing different environmental conditions when compared to subpopulation in their native habitat. Disturbed-habitat subpopulations showed a faster life-history. This faster life history is associated with a weaker spatial genetic structure and higher levels of inbreeding in the disturbed-habitat subpopulations. In addition, higher light availability in the disturbed habitat seems to be a major agent of selection on traits like leaf production that have the potential to respond to selection in these subpopulations. Different traits were under selection in the native-habitat subpopulations, suggesting the potential for genetic differentiation between native and disturbed-habitat subpopulations. Genotype by environment interactions in seed germination and seedling survival, in response to light and water availability, further suggested that subpopulations can adaptively diverge between habitats, but the relative role of genetic and environmental factors, particularly maternal effects, on the magnitude and rate of genetic differentiation between subpopulations remains to be evaluated. These results suggest that habitat degradation can have important consequences for the evolutionary dynamics of populations of this cycad, not necessarily typical of habitat loss and fragmentation. This study identified factors and processes important for population persistence in degraded habitats, but population responses to habitat degradation are complex. Thus further studies and long-term experiments are required for better understanding the effects of habitat degradation on population viability.

Limportance des différentes sources de variation phénotypique que sont ladaptation, la plasticité phénotypique, les effets maternels environnementaux, le niveau de ploïdie et la dérive génétique, a été analysée pour différents traits dhistoire de vie, au sein de laire colonisée par une espèce végétale invasive. A cette fin, plusieurs expériences en jardins communs ont été installées, dont deux en transplantations réciproques. Les populations considérées étaient localisées en Belgique, en France, ainsi que dans laire dindigénat de lespèce. Senecio inaequidens DC. (Asteraceae), lespèce étudiée dans ce travail, est une plante dorigine africaine accidentellement introduite en Europe par le commerce lainier, vers la fin du 19ème siècle. Dans son aire dindigénat, elle présente deux niveaux de ploïdie, diploïde et tétraploïde. Seuls des plants tétraploïdes sont recensés en Europe. Lespèce présente un historique de colonisation particulier, bien documenté, qui en fait un modèle idéal pour les études évolutives. Les traits dhistoire de vie considérés ont été scindés en deux groupes. Les premiers concernaient la germination, la croissance et la reproduction sexuée. Les sources de variation phénotypique dans ces traits ont été principalement analysées en relation avec les variations climatiques dans laire dinvasion, le long de gradients daltitude, ainsi quen relation avec le niveau de ploïdie et laire dorigine (aire dindigénat vs aire dinvasion). Le deuxième groupe de traits considérés concernaient les capacités de dispersion de lespèce. Celles-ci ont été modélisées. La variabilité phénotypique dans ces traits a ensuite été analysée, parmi les populations françaises, en relation avec léloignement depuis le site de première introduction. Les résultats ont montré des différences entre les cytotypes de lespèce, principalement dans les capacités de survie hivernale. Le long des gradients daltitude, les populations de S. inaequidens présentaient des différenciations phénotypiques de type clinal, dans les traits de croissance. Ces différenciations étaient dorigine génétique, même si les effets maternels environnementaux sont apparus comme des sources non-négligeables de variation phénotypique dans les zones à climat rigoureux. Parmi les traits liés à la dispersion, le plume loading était le mieux corrélé aux capacités de dispersion par le vent. Des différenciations clinales ont été détectées dans les traits de dispersion, en jardin commun, mais nont pas été vérifiées en populations naturelles.

L'étude porte sur l'allocation de ressources aux œufs d’oiseaux selon les caractéristiques du male partenaire ou de l’environnement. les données étudiées sont : taille de la ponte et caractéristiques des œufs (masse, masse des constituants, concentration de testostérone, lysozyme, ovotransferrin). les caractéristiques du male prises en compte sont s'il est choisi ou non par la femelle et son statut social. en plus, l’effet du bruit et d’un vaccination couple avec un surproduction des œufs sont pris en compte. Deux expériences ont été menées sur le canari domestique (Serinus canaria) en laboratoire, au sein du LECC de Paris Ouest Nanterre. Deux expériences ont eu lieu en milieu semi-naturel au DiSIT de l’Università degli Studi del Piemonte Orientale (Italie) sur la perdrix grise (Perdix perdix) et rouge (Alectoris rufa).Chez la perdrix grise, nous observons effets positifs de la préférence et du statut social sur la testostérone et sur le taux d’éclosion. cette hormone peut rendre les oisillons nidifuges plus compétitifs vis-à-vis des couvées voisines. Chez le canari, on observe un effet positif de la préférence sur le poids des œufs et sur le lysozyme, important substance antimicrobienne. en plus, on a trouvé un influence négative du bruit sur la sélection sexuelle et sur le numéro des œufs pondues.Chez la perdrix rouge, nous observons variations significatives des components de l’oeuf en relation a la surproduction des œufs (épuisement des ressources). En conclusion, la femelle n'est pas seule à déterminer les caractéristiques des œufs. le male partenaire et l’environnement ont aussi une influence sur leur composition et donc sur le développement des jeunes. / The study focuses on the allocation of resources to eggs of birds according to the characteristics of the male partner or the environment. The data studied are: clutch size and egg characteristics (mass, mass constituents, testosterone, lysozyme, ovotransferrin). Male characteristics taken into account are if it is selected or not by the female and his social status. In addition, the effect of noise and a vaccination coupled with an overproduction of eggs are taken into account.Two experiments were conducted on the domestic canary (Serinus canaria) in the LECC laboratory of Paris Ouest Nanterre.Two experiments were carried out in semi-natural condition to DiSIT laboratory of the Università degli Studi del Piemonte Orientale (Italy) on grey partridge (Perdix perdix) and red-legged partridge (Alectoris rufa).In the grey partridge, positives effects of preference and social status are observed on testosterone and hatchability. This hormone can make precocial chicks more competitive with neighboring broods.In canaries, there is a positive effect of preference on egg weight and lysozyme, an important antimicrobial substance. In addition, a negative influence of noise is found on sexual selection and number of eggs laid.In the red-legged partridge, significant changes in the egg components are observed in relation to the overproduction of eggs (depletion).In conclusion, the female is not only to determine the characteristics of eggs. The male partner and the environment also have an influence on their composition and therefore on the development of chicks.

Antimicrobial proteins contained in the albumen represent maternal effects, including the non- genetic component allocated into the egg during its oogenesis. Especially for species, whose broods are exposed to environmental influences until completation, these proteins play a crucial role in the viability of embryos due to their potential to influence the risk of microbial infection, which is considered one of the main causes of reduced hatchability. Also, it is assumed that these proteins, beacause of their specific traits, may influence phenotype of chicks, especially its size and immunity in the early postembryonal stage. In my thesis I focused on three antimicrobial proteins of avian egg white - avidin, lysozyme and ovotransferrin, which vary in their antimicrobial activity. For a better understanding of causal relationships between the concentrations of these proteins in the albumen and their effect on hatching success or offspring phenotype, a series of manipulation experiments and correlative measurements were performed. These experiments were held on the eggs of two precocial species - Japanese Quail (Coturnix japonica) and Mallard (Anas platyrhynchos). Our results indicate a crucial role of antimicrobial proteins in reducing the risk of bacterial infection and their natural concentration...

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Knowledge of offspring production (recruitment) is fundamental to understanding and forecasting the dynamics of a population. In this thesis, I focus on two demographic characteristics of fish stocks that are important to recruitment: population density and age structure. First, populations produce more recruits at low density, but quantifying this response has proven difficult. Using data from hundreds of populations of walleye (Sander vitreus), an economically important freshwater fish, I demonstrate that the growing-degree-day metric (a temperature index) is better than age at explaining variation in density-dependent growth and maturity both within and among populations. I then incorporate multi-lake measures of density-dependent life history change into a temperature-based biphasic model of growth and reproduction to predict sustainable rates of mortality for walleye throughout most of their range. Second, the age (or size) structure of a population may also affect recruitment because of positive effects of maternal age on offspring production and survival; however, evidence for these ‘maternal influences’ on recruitment is limited. Using both an analytical model and a meta-analysis of stock-recruitment data from 25 species of exploited marine fish, I show that (i) maximum reproductive rate increased with the mean age of adults in a population, and (ii) the importance of age structure increased with a species’ longevity. I then demonstrate a similar effect of maternal influences on reproductive rate in a detailed study of Lake Erie walleye. By highlighting the importance of fisheries-induced demographic change to recruitment, this thesis provides insight into past and present failures. However, it also demonstrates clearly the benefits of proactive management strategies that (i) identify and respect the limits of exploitation, (ii) protect from exploitation reproductively valuable individuals—principles that apply generally to any freshwater, marine, or terrestrial species that is of recreational, commercial, or conservation value.

Knowledge of offspring production (recruitment) is fundamental to understanding and forecasting the dynamics of a population. In this thesis, I focus on two demographic characteristics of fish stocks that are important to recruitment: population density and age structure. First, populations produce more recruits at low density, but quantifying this response has proven difficult. Using data from hundreds of populations of walleye (Sander vitreus), an economically important freshwater fish, I demonstrate that the growing-degree-day metric (a temperature index) is better than age at explaining variation in density-dependent growth and maturity both within and among populations. I then incorporate multi-lake measures of density-dependent life history change into a temperature-based biphasic model of growth and reproduction to predict sustainable rates of mortality for walleye throughout most of their range. Second, the age (or size) structure of a population may also affect recruitment because of positive effects of maternal age on offspring production and survival; however, evidence for these ‘maternal influences’ on recruitment is limited. Using both an analytical model and a meta-analysis of stock-recruitment data from 25 species of exploited marine fish, I show that (i) maximum reproductive rate increased with the mean age of adults in a population, and (ii) the importance of age structure increased with a species’ longevity. I then demonstrate a similar effect of maternal influences on reproductive rate in a detailed study of Lake Erie walleye. By highlighting the importance of fisheries-induced demographic change to recruitment, this thesis provides insight into past and present failures. However, it also demonstrates clearly the benefits of proactive management strategies that (i) identify and respect the limits of exploitation, (ii) protect from exploitation reproductively valuable individuals—principles that apply generally to any freshwater, marine, or terrestrial species that is of recreational, commercial, or conservation value.