Conservation programs for breeding ducks in North America are typically designed to enhance nest success by establishing or restoring attractive perennial nesting cover or promoting favourable agricultural practices. Thus, a central objective is to attract ducks to habitats where females have higher survival and reproductive rates, primarily greater nest success. Using data collected from 1993 – 2000, I investigated hypotheses proposed to explain inconsistent patterns of habitat selection detected during nesting and brood–rearing stages in free-ranging mallards (Anas platyrhynchos) throughout the Canadian Prairie Parklands. By simultaneously considering indices of body condition and size of male and female mallards and plumage score of males, I also evaluated the role of male quality in reproductive investment and patterns of breeding success of females. In general, wild mallards mated assortatively by body condition but not body size. Yearling females nested earlier and had higher nest survival when mated to males with better plumage quality. When paired with larger-bodied males, yearling females renested more often, whereas nest and brood survival increased among older females. I characterized the habitat composition of 100 and 500 m radius buffers surrounding nest sites and related habitat features to survival of nests, broods and females. Habitat selection trade-offs were detected among perennial habitats and planted cover, such that nest survival increased in these habitats whereas duckling survival decreased. Furthermore, at large spatial scales, nest survival decreased in areas with greater amounts of cropland whereas duckling survival increased. Survival rates of females increased with greater amounts of seasonal wetlands, but nest survival decreased in such areas. Semi-permanent wetlands were associated with decreased nest survival at larger spatial scales, but associated with higher nest success at finer scales. Benefits of increasing perennial and planted cover habitats to increase nest survival could be partly offset by costs in terms of lower duckling survival, whereas opposite patterns existed in areas of abundant seasonal. The restoration of seasonal wetlands in perennial habitats could offset these trade-offs but net impacts of habitat selection and survival trade-offs on annual reproductive success must first be evaluated.

A central question in life history theory is, what combination of traits and behaviors will lead to the highest reproductive success throughout a lifetime. The trade-off between current and future reproduction is central to the lifetime reproductive success of an organism. If there is a cost to reproduction, then allocation of energy to current reproduction will come at a cost to future reproduction. We expect young individuals to favor future reproduction over current reproduction and that balance shifts to current reproduction as they age (i.e. terminal investment hypothesis). However, how this transition from an emphasis on future reproduction to emphasis on current reproduction changes throughout a lifetime should depend on environmental factors like mortality and resource availability. We test for the generality of terminal investment across three species of poecilliid fishes in a range of environments. We found evidence of terminal investment in all three species in both high and low mortality environments and high and low resource availability environments. In general, high mortality or high resource availability tended to result in a decreased slope of the relationship between reproductive allocation and body size. Terminal investment appears to be general, even though there was an effect of high mortality and resource availability, it was not sufficient to completely preclude terminal investment.

Extra-pair paternity, resulting from sexual promiscuity, is frequently detected in socially monogamous passerines. Previous studies on extra-pair paternity in birds have identified several traits correlated with increased fertilization success of males. However, the effect of experimental manipulation of ornament expression on male fertilization success has only seldom been evaluated. The aim of this thesis is to reveal the potential link between the size of a trait suposedly playing a role in female mate choice decision and male fertilization success in collared flycatchers (Ficedula albicollis), using experimental manipulation of male forehead white patch size. In addition, mating success, mating speed of the manipulated and control individuals and size of a brood (a proxy for female reproductive investments) were evaluated. Results indicate that forehead patch size manipulation did not affect male social pairing success (mating speed), his social mate reproductive investments (brood size) or male extra-pair and within-pair fertilization success. Keywords: extra-pair paternity, sexual selection, reproductive success, collared flycatcher

Le “coût de la reproduction” est un concept qui définit qu’un investissement à la reproduction élevé a un prix qui se paye ultérieurement par une accélération de la sénescence. Cela peut notamment traduire des compromis entre la reproduction et d’autres fonctions physiologiques comme la défense antioxydante. Chez l’huître creuse Crassostrea gigas, la reproduction représente une fonction physiologique majeure. Dans le cadre des études effectuées pour comprendre les mortalités estivales affectant cette espèce, une corrélation négative entre effort reproducteur et survie a été observée. D’autre part, des gènes antioxydants ont été mis en évidence comme différentiellement exprimés entre les lignées d’huîtres sélectionnées pour leur résistance ou leur sensibilité aux mortalités estivales. Certaines études proposent que la susceptibilité au stress oxydant puisse représenter un coût de la reproduction participant au processus de sénescence. Dans ce contexte, nous avons analysé la capacité antioxydante des huîtres en fonction de leur investissement reproducteur. Pour cela, la technique d’ARN interférence a été utilisée pour manipuler l’effort reproducteur des huîtres. L’expression des principales enzymes antioxydantes (taux de transcrits et activités enzymatiques) et le dosage de dommages oxydatifs ont ensuite été mesurés dans différents tissus et cellules de l’organisme (branchies, gonade, hémocytes et gamètes). Les résultats obtenus dans le cadre de cette thèse suggèrent que la capacité antioxydante de C. gigas est particulièrement efficace et que la reproduction seule n’est pas suffisante pour induire un stress oxydant. Cette capacité antioxydante apparaît comme tissu-spécifique voire cellule-spécifique et le métabolisme du glutathion semble jouer un rôle majeur dans cette protection. Cette grande résistance au stress oxydant contribuerait à faire de C. gigas une espèce particulièrement adaptée à la vie dans des environnements stressants. / The “cost of reproduction” is a concept defining that a high reproductive investment has a price that is paid later by an acceleration of senescence. That may translate tradeoff between reproduction and other physiological functions such as antioxidant defense. In the Pacific oyster Crassostrea gigas, reproduction is a major physiological function. In a study led to understand the summer mortalities affecting this species, a negative correlation between reproductive effort and survival was observed. Moreover, some antioxidant genes were identified as differentially expressed between lines of oysters selected for resistance or susceptibility to summer mortalities. Some studies suggest that the susceptibility to oxidative stress may represent a cost of reproduction taking part to the process of senescence. In this context, we analyzed the antioxidant capacity of oysters according to their reproductive investment. For this, the technique of RNA interference was used to manipulate the reproductive effort of oysters. The expression of the main antioxidant enzymes (transcript levels and enzyme activities) and the dosage of oxidative damages were then measured in different tissues and cells of the organism (gills, gonad, hemocytes and gametes). The results obtained in this thesis suggest that the antioxidant capacity of C. gigas is particularly effective and that reproduction alone is not sufficient to induce oxidative stress. This antioxidant capacity appears to be tissue-specific even cell-specific and glutathione metabolism would to play a major role in this protection. This resistance to oxidative stress would make C. gigas be a species particularly adapted to life in stressful environments.

Esta tese trata, primariamente, da definição do status taxonômico do amplamente conhecido corrupto de praia ou ghost shrimp Callichirus major (Say, 1818) sensu lato (Decapoda, Axiidea, Callianassidae) ocorrente na costa brasileira (Capítulo I). A definição deste táxon era um tanto incerta até o momento, levando-se em conta a grande similaridade morfológica entre as espécies que compõem o complexo C. major. Alguns estudos morfológicos, moleculares e larvais foram realizados anteriormente de forma isolada, e sem uma abrangência ao longo de toda sua área de distribuição. Entretanto, nenhum destes estudos foi conclusivo quanto à validade ou não do nome C. major ser aplicado à espécie brasileira. De forma complementar, esta tese objetivou o estudo sobre o investimento reprodutivo e sobre a ecologia populacional de uma de suas populações do litoral norte do Estado de São Paulo (Capítulos II e III, respectivamente). Os resultados desta tese são apresentados em capítulos separados, devido ao fato deles tratarem de assuntos distintos envolvendo a taxonomia/sistemática molecular, biologia reprodutiva e a ecologia populacional da espécie. Cada capítulo contém suas próprias sessões: Resumo, Introdução, Material & Métodos, Resultados, Discussão e Referências. Também, cada capítulo apresentado nesta tese é equivalente a um artigo submetido ou a ser submetido a revistas científicas e encontram-se formatados de acordo com as normas das revistas escolhidas. / This thesis is primarily about the taxonomic status of the ghost shrimp Callichirus major (Say, 1818) sensu lato (Decapoda, Axiidea, Callianassidae) from Brazilian coastlines (Chapter I). The taxonomic status of C. major complex was uncertain until now, due to the very large range of distribution and morphological characters shared among species. Some morphologic, molecular and larval studies were made in isolated perspective and without a distribution range overview before that. None of them were conclusive about the validity to name C. major been applied for the Brazilian species. In a complementary way, this thesis aimed the reproductive output and the population ecology of the species in a sandy beach in the North Shore, State of São Paulo, Brazil (Chapters II and III, respectively). The results of this thesis were presented in distinct chapters due to different approaches related to taxonomy/systematics, reproductive biology and population ecology of this species. Each chapter has its own sections: Abstract, Introduction, Material and Methods, Results, Discussion and References. Those chapters are equivalent to an article submitted or to be submitted to scientific journals, and are formatted according to the author guidelines of each journal.

Esta tese trata, primariamente, da definição do status taxonômico do amplamente conhecido corrupto de praia ou ghost shrimp Callichirus major (Say, 1818) sensu lato (Decapoda, Axiidea, Callianassidae) ocorrente na costa brasileira (Capítulo I). A definição deste táxon era um tanto incerta até o momento, levando-se em conta a grande similaridade morfológica entre as espécies que compõem o complexo C. major. Alguns estudos morfológicos, moleculares e larvais foram realizados anteriormente de forma isolada, e sem uma abrangência ao longo de toda sua área de distribuição. Entretanto, nenhum destes estudos foi conclusivo quanto à validade ou não do nome C. major ser aplicado à espécie brasileira. De forma complementar, esta tese objetivou o estudo sobre o investimento reprodutivo e sobre a ecologia populacional de uma de suas populações do litoral norte do Estado de São Paulo (Capítulos II e III, respectivamente). Os resultados desta tese são apresentados em capítulos separados, devido ao fato deles tratarem de assuntos distintos envolvendo a taxonomia/sistemática molecular, biologia reprodutiva e a ecologia populacional da espécie. Cada capítulo contém suas próprias sessões: Resumo, Introdução, Material & Métodos, Resultados, Discussão e Referências. Também, cada capítulo apresentado nesta tese é equivalente a um artigo submetido ou a ser submetido a revistas científicas e encontram-se formatados de acordo com as normas das revistas escolhidas. / This thesis is primarily about the taxonomic status of the ghost shrimp Callichirus major (Say, 1818) sensu lato (Decapoda, Axiidea, Callianassidae) from Brazilian coastlines (Chapter I). The taxonomic status of C. major complex was uncertain until now, due to the very large range of distribution and morphological characters shared among species. Some morphologic, molecular and larval studies were made in isolated perspective and without a distribution range overview before that. None of them were conclusive about the validity to name C. major been applied for the Brazilian species. In a complementary way, this thesis aimed the reproductive output and the population ecology of the species in a sandy beach in the North Shore, State of São Paulo, Brazil (Chapters II and III, respectively). The results of this thesis were presented in distinct chapters due to different approaches related to taxonomy/systematics, reproductive biology and population ecology of this species. Each chapter has its own sections: Abstract, Introduction, Material and Methods, Results, Discussion and References. Those chapters are equivalent to an article submitted or to be submitted to scientific journals, and are formatted according to the author guidelines of each journal.

La sélection sexuelle est une composante de la sélection naturelle qui génère des différences de succès reproducteur entre les individus par le filtre de la reproduction, et influence donc la transmission intergénérationnelle des gènes. Dans le cadre de cette thèse, l’effet de la variabilité de l’environnement hydraulique sur la sélection sexuelle chez la truite commune a été étudié à différentes échelles : intra- et inter-populationnelle. Des méthodes nouvelles permettant de mieux appréhender l’investissement reproducteur, ainsi que de décomposer l’effet des traits sur la fitness des individus en fonction des différentes étapes de la sélection sexuelle, ont été mises au point. Les expériences réalisées en milieux naturel et semi-naturel indiquent que la variabilité environnementale n’affecte pas le choix d’habitat de reproduction par les femelles, mais peut affecter l’investissement reproducteur dans la compétition par exemple, ainsi que les flux de gènes entre des populations génétiquement distinctes. Ces résultats permettent une première projection de l’évolution de la sélection sexuelle dans le contexte du changement climatique qui prédit l’augmentation de la variabilité hydrologique en zone tempérée. / As a component of natural selection, sexual selection produces variation in reproductive success throughout the reproductive period, and therefore impacts genes transmission between generations. During this PhD, the effect of variation in hydraulic environment on sexual selection in brown trout was investigated at both within and between populations scales. New approaches to improve estimation of reproductive investment, as well as models to decompose the effect of traits on individual fitness at each stage of sexual selection, were developed. Experiments in natural and semi-natural environments indicate that environmental variation does not impact reproduction habitat choice by females, but it can modify reproductive investment in some populations, as well as it can control gene flow between genetically distinct populations. These results help to understand the evolution of sexual selection in the broad context of increasing stochastic variations of river systems hydrology as predicted by climate change models in temperate areas.

An appreciation of the role of mutualism is essential when studying ecology and evolution in most ecosystems. Information covering aspects of mutualistic interactions can serve as a complement to the somewhat one-sided perspective from the 1950’s and 60’s that is used when teaching biology. In this thesis I applied an in-depth approach in which variation in the interspecific interaction between Aphis fabae aphids and Lasius niger ants was studied both in the field and in the laboratory. An emphasis was put on studies spanning several consecutive aphid generations. This approach revealed important differences between ant tended aphids and those without ants. In the lab, I found an initial decrease in aphid adult size and reproductive investment in the first generations after the start of ant tending, which was followed by a recovery to the pre-tending situation after about four generations. Another laboratory experiment showed an increase in alate (winged aphid) production from exposure to aphid alarm pheromones, and an even stronger decrease in alate production from ant attendance, suggesting that ants have gained the upper hand in an evolutionary conflict over aphid dispersal. Results from a field experiment further emphasized the possibility of negative effects of ants on aphids, showing that ant-tended aphid colonies experienced a higher rate of parasitoid attacks, produced fewer alates and embryos in adult aphids. The thesis highlights the scope for variation in the net effect of the interaction for aphids, and argues that, depending on the environmental circumstances, the interaction may sometimes and perhaps even often not really be a case of mutualism. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 4: Manuscript.</p>

L'objectif principal de cette thèse est d'étudier comment la sélection naturelle façonne les traits d'histoire de vie et le comportement des animaux en fonction de l'environnement écologique dans lequel ils évoluent. Ce cadre théorique soulève des hypothèses spécifiques concernant les processus de reproduction, de dispersion et d'approvisionnement chez le parasitoïde Ibalia leucospoides. Les expériences d'écologie comportementale et d'écophysiologie menées sur des parasitoïdes femelles d' Ibalia leucospoides démontrent principalement que (1) la proportion d'oeufs matures que possède la femelle à l'émergence est élevée par rapport à sa fécondité potentielle : I. Leucospoides adopte une stratégie proovigénique ; (2) l'alimentation a un effet négligeable sur les femelles adultes : elle n'influence ni la maturation des oeufs, ni la survie, ni les capacités de vol ; (3) dans nos conditions expérimentales, la capacité de vol dépend des caractéristiques morphologiques du parasitoïde (taille et charge alaire) ; et (4) concernant la recherche d'hôtes, les femelles sont capables de discerner des différences dans la qualité des patchs d'hôtes à distance, sans les échantillonner. D'autre part, le temps d'exploitation d'un patch dépend des informations obtenues des patchs voisins. Le succès reproductif du parasitoïde proovigénique Ibalia leucospoides, n'est pas limité par le manque de nourriture chez l'adulte. La stratégie d'allocation des ressources entre les différentes fonctions biologiques, ainsi que le comportement d'approvisionnement adopté par cette espèce de parasitoïde pourraient vraisemblablement être une réponse aux caractéristiques de l'habitat, telle que la distribution fortement agrégée des Sirex noctilio, l'hôte, ainsi que la disponibilité des ressources (i.e. hôtes et nourriture) / The central aim of this thesis is to explore how natural selection shapes life history traits and behaviuors according to the ecological environment in which an animal exists. This overall framework leads to specific hypotheses concerning the reproductive, dispersal and foraging processes in the parasitoid Ibalia leucospoides. The experiments in behavioural ecology and eco-physiology in female parasitoids of Ibalia leucospoides show as main results, that (1) the proportion of the potential lifetime eggs complement that is mature at female emergence is high; (2) low dependency on adult female feeding, not only for egg maturation but also for survival and flight; (3) under our experimental conditions flight capacity depends on the morphological characteristics of the parasitoid (size and wing loading); and (4) regarding host foraging, females accurately assess differences in host patch quality from a distance without the need of displaying a sampling process; in addition that patch exploitation times depend on the information obtained from the surrounding patches. The reproductive success of I. leucospoides, a proovigenic parasitoid, is not constrained by adult food deprivation. Both the resource allocation strategy toward the different biological functions and the foraging behaviour adopted by this parasitoid species may well be in respond to habitat characteristics, such as a strongly aggregated distribution of Sirex noctilio, the host, as well as to the resources availability (i.e. host and food)

Une question fondamentale de la biologie évolutive porte sur la compréhension des mécanismes sous-tendant les processus évolutifs et l’évolution des compromis entre les traits d’histoire de vie. Parmi ces mécanismes, les télomères suscitent un intérêt particulier. Les télomères sont localisés à l’extrémité des chromosomes eucaryotes et participent à la sénescence cellulaire et au vieillissement des individus. La longueur des télomères est susceptible de donner des indications sur le mode de vie et l’état physiologique des organismes. Le but de cette thèse a été de comprendre quels sont les facteurs déterminant la longueur des télomères et leur implication dans les compromis évolutifs, ceci en établissant : si la taille des télomères est-elle héritable? Le taux de perte des télomères est-il affecté par des facteurs environnementaux? Quel lien entre les télomères, la maintenance individuelle et la qualité des individus? Il résulte de ce travail que la longueur des télomères est partiellement déterminée par les facteurs génétiques, elle semble aussi influencée par les facteurs environnementaux. En effet, le coût de la reproduction, ainsi que la modification des trajectoires de croissance, ont des effets néfastes sur la longueur des télomères. L’effet de la manipulation expérimentale de l’activité télomérase indique un lien entre les télomères et la maintenance individuelle, suggérant que les télomères sont susceptibles de donner des indications sur la qualité des individus. Ce travail de thèse montre que la dynamique des télomères est un mécanisme sous-jacent des compromis évolutifs, et présente un intérêt considérable pour la compréhension des processus évolutifs. / Evolutionary pathways through which life histories may have evolved are numerous. Consequently identifying the underlying mechanisms of those processes is crucial for our overall comprehension of the origin of life diversity. Thus, there is clearly a great potential in the study of repetitive DNA sequences that cap eukaryotic chromosomes, the telomeres. Telomeres are structures involved in cell senescence and determine the rate of ageing. They are thought to reflect more than just the effects ofage and to play an important role in linking life conditions and senescence. Indeed, telomeres could act as markers of life style and of past-historical levels of stress and inform on individuals’ current physiological quality. This thesis aims to determine whether telomeres could act as a mechanism underlying life history trade-offs by establishing the pattern of heritability of telomere length; characterising telomere length’s determinants; testing the nature of the relationship between telomerelength and individual maintenance, and ultimately with individual quality. The present work shows that telomere dynamics is determined by genetic factors, but is probably predominantly affected by lifestyle factors. As such, environmental conditions experienced during the growth period, as well as during adulthood (i.e. level of reproductive effort) have a strong impact on individuals’ telomere length. Experimental manipulation of telomerase activity showed that telomere length could be linked to individual maintenance and thus might be indicative of individual quality. Altogether, these results highlight that telomere dynamics might provide a functional link between life history traits.