In migratory vertebrates, the optimal timing of successive life history stages is relatively inflexible. As a result, life history trade-offs that occur during breeding may influence individual success in subsequent stages because there is little time to mitigate negative costs that are incurred, or because the onset of subsequent stages is delayed. In migratory songbirds, understanding how breeding events carry over to influence individual success has been challenging because individuals are difficult to track once breeding is complete. I studied an island breeding population of migratory Savannah sparrows (Passerculus sandwichensis) and tracked individuals from breeding up until the onset of autumn migration. In Chapter 1, I investigated the effects of early life events on body condition during the pre-migratory period and first year apparent survival. I found that juveniles fledging from larger broods were in poorer condition at fledging, had lower fat stores prior to migration, and had lower first year apparent survival. In Chapter 2, I examined the effects of life history trade-offs made by adults during breeding on pre-migratory body condition and annual apparent survival. I did not find evidence for a trade-off between reproductive effort or date of breeding completion with annual apparent survival or body condition during the pre-migratory period, but instead found that adults with the highest reproductive effort and later dates of breeding completion were more likely to survive until the following year. In Chapter 3, I examined the effect of timing of breeding completion and fledging on the date of fall migration. I found that both variables had strong positive effects on date of departure. Together, my results suggest that successful migration in juveniles is influenced by early life events, but that any potential costs incurred by adults during the breeding season likely has little influence on survival during migration.

Le manguier (Mangifera indica L.), cinquième production fruitière mondiale, est une espèce à production irrégulière. L’irrégularité de production a des retombées économiques marquées pour tous les acteurs de la filière fruitière. Il apparait donc important de mieux comprendre les mécanismes qui déclenchent et entretiennent ce phénomène d’irrégularité de production. Le premier objectif de cette thèse est d’apporter un regard nouveau sur l’irrégularité de production du manguier en mobilisant le concept des coûts de la reproduction. Cette étude est effectuée à plusieurs échelles spatiales, unité de croissance (UC), branche charpentière, arbre, et de manière dynamique sur quatre cultivars. Les résultats montrent un effet négatif, ou coût, de la reproduction sur la croissance végétative au cycle suivant, avec des comportements contrastés des cultivars en lien avec leur irrégularité de production. En particulier, un effort reproducteur important diminue la probabilité de débourrement végétatif des UCs porteuses. Le second objectif est d’étudier, chez deux cultivars et à l’échelle de l’UC, les modifications anatomiques et hydrauliques liées à la croissance du fruit, et des mécanismes trophiques et hormonaux contribuant à cet effet négatif de la reproduction sur le débourrement végétatif. Les résultats montrent que la reproduction entraîne une différenciation du cambium de l’UC porteuse principalement en phloème. Les inflorescences et les fruits diffusent de l’auxine qui inhibe le démarrage végétatif des UCs reproductrices. Les fruits en croissance mobilisent les réserves en amidon de l’UC porteuse. Les faibles teneurs en amidon de ces UCs pendant et après la récolte contribuent à réduire leur probabilité de débourrement végétatif, et/ou à le retarder lorsqu’il a lieu. Les résultats diffèrent entre les deux cultivars, et l’implication de ces mécanismes dans l’irrégularité de production est discutée. Nos résultats permettent de mieux comprendre les facteurs qui entretiennent l’irrégularité ou l’alternance de production de différents cultivars de manguiers. De façon appliquée, ils suggèrent que des techniques de taille adaptées à chaque cultivar et nature d’UC pourraient permettre d’obtenir une production plus régulière chaque année. / The mango tree (Mangifera indica), the fifth fruit crop production in the world, is characterized by an irregular bearing pattern. Irregular bearing is responsible for economic difficulties for producers and for all actors along the fruit industry chain. A better understanding of mechanisms which trigger and maintain irregular bearing is therefore necessary. The first objective of this study is to provide a new perspective on irregular bearing of the mango tree using a concept developed in ecology and evolutionary biology, the costs of reproduction. The experiment was carried out dynamically at several spatial scales, growth unit (GU), scaffold branch, tree, and on four cultivars. Results show a negative effect, or cost, of reproduction on vegetative growth during the following cycle, with cultivar-specific behaviors related to their bearing pattern. In particular, an important reproductive effort reduces the probability of vegetative burst of the bearing GUs. The second objective is to study, for two cultivars and at the GU scale, the anatomical changes of the bearing axis during fruit growth, and hormonal and trophic mechanisms involved in the negative effects of reproduction on vegetative bud outgrowth. Results show that reproduction leads to cambium differentiation mainly in phloem, favoring nutrients and water supply to the fruit. Inflorescences and growing fruits release auxin, contributing to vegetative bud burst inhibition on fruiting GUs. Growing fruits mobilize starch reserves of bearing GUs. Their low starch content at and after harvest contributes to decrease their probability of vegetative burst, and/or delay it when it occurs. The results reveal a strong cultivar effect, and the involvement of these mechanisms in irregular bearing is discussed. Our results allow to better understand the factors maintaining irregular or alternate bearing of different mango cultivars. From a practical perspective, they suggest that pruning techniques adapted to each cultivar and GU fate may contribute to more regular production each year.

This project describes various aspects of the breeding ecology and behaviour of the brown falcon Falco berigora, a common but poorly study Australian raptor. In particular it examines (a) the main influences on reproductive success; (b) tests predictions of theories proposed to explain the evolution and maintenance of sexual size dimorphism (RSD; females the larger sex) in raptors; and (c) investigates sex allocation patterns in the light of current sex ratio and parental investment theory. The study was conducted between July 1999 and June 2002 approximately 35 km southwest of Melbourne, at the Western Treatment Plant (WTP), Werribee (38°0’S 144°34’E) and surrounds, a total area of approximately 150 km2.¶ · In all plumage and bare part colouration of 160 free-flying falcons was described. The majority of variation in these characters could be attributed to distinct age and/or sex differences as opposed to previously described colour ‘morphs’.¶ · Nestling chronology and development is described and formulae based on wing length derived for determining nestling age. An accurate field-based test for determining nestling sex at banding age is also presented.¶ · Strong sex role differentiation was apparent during breeding; typical of falcons females performed most parental duties whilst males predominantly hunted for their brood and partner. Based on observations of marked individuals, both sexes of brown falcons aggressively defended mutual territories throughout the year, with just 10% of each sex changing territories during the entire study period. Males performed territorial displays more frequently than females, the latter rarely displaying alone.¶ · The diet of the population as a whole was very broad, but within pairs both sexes predominantly specialised on either lagomorphs, small ground prey (e.g. house mice Mus musculus), small birds, large birds or reptiles, according to availability.¶ · Reproductive parameters such as clutch size and the duration of parental care were constant across all years, however marked annual differences in brood size and the proportion of pairs breeding were evident.¶ · Age was an important influence upon reproductive success and survival, with immature birds inferior to adults in both areas. However, interannual differences were by far the most influential factor on breeding success and female survival. Heavy rain downpours were implicated as the main determinant of reproductive success and adult female mortality in a population largely devoid of predation or human interference.¶ · Female-female competition for territorial vacancies was intense; larger adult females were more likely to be recruited and once breeding fledged more offspring. In contrast, male recruitment and breeding success was unrelated to either body size or condition indices, although smaller immature males were more likely to survive to the next breeding season. This directional selection is consistent only with the predictions of the intrasexual competition hypothesis.¶ · Despite marked RSD (males c. 75% of female body mass), throughout the nestling phase female nestlings did not require greater quantities of food than their male siblings. However, female parents fed their last-hatched sons but not daughters, resulting in the complete mortality of all last-hatched female offspring in focal nests. Given last-hatched nestlings suffered markedly reduced growth rates and female, but not male, body size is important in determining recruitment patterns, the biased allocation amongst last-hatched offspring is likely to reflect differing benefits associated with investing in small members of each sex, consistent with broad-scale Trivers-Willard effects. Recruitment patterns support this, with surviving last-hatched females, in contrast to males, unable to gain recruitment into the breeding population upon their return to the study site.¶ Thus selection appears to act at the nestling, immature and adult stages to maintain RSD in the focal population. Larger females were favoured in the nestling phase, at recruitment and once breeding had greater reproductive success. In contrast, selection favoured a reduction or maintenance of immature male size as smaller birds had a greater chance of survival in the year following recruitment than their larger counterparts; thereafter male size was unimportant. Together, this directional selection favouring increased female competitive ability is consistent only with the predictions of the intrasexual competition hypothesis, which appears the most probable in explaining the maintenance and perhaps evolution of RSD in raptors.

Les coûts de la reproduction sont un compromis biologique (trade-off ) fondamental en théorie des histoires de vie. Par ce compromis, le succès, pour un organisme, d’un évènement de reproduction réduit sa survie et sa fertilité futures. Pour les écologues, ce trade-off correspond principalement à un compromis physiologique résultant d’un processus d’allocation ayant lieu à chaque instant et au niveau de chaque individu. Au contraire, en démographie évolutive, il est envisagé comme un trade-off génétique découlant du polymorphisme génotypique d’un gène pléiotropique agissant de manière antagoniste sur la reproduction aux jeunes âges et la fitness aux âges élevés. L’étude des mécanismes des coûts de la reproduction, physiologiques et génétiques, de leur possible cohabitation et de leur effets relatifs, croisés et conjoints est le sujet de cette thèse. Un examen attentif de la définition originelle des coûts de la reproduction par Williams (1966), nous permet de construire un modèle théorique des coûts physiologiques intégrant leurs aspects mécaniques et évolutifs. Cette construction nous permet d’induire l’intensité des coûts de la reproduction selon la position d’un organisme sur trois continuums d’histoire de vie: "slow-fast", "income-capital breeders" et "quantity-quality".A partir de la décomposition, par Stearns (1989b), de l’architecture des contraintes d’histoire de vie en trois parties – le niveau génotypique, la structure intermédiaire et le niveau phénotypique – nous étendons notre modèle conceptuel pour y intégrer à la fois des trade-offs physiologiques et génétiques. Cela nous permet d’inférer les effets de l’environnement, de sa variance et de la stochasticité individuelle sur la détectabilité de chaque famille de coûts. La différence entre coûts physiologiques et génétiques se retrouve également dans leur modélisation mathématique. Il est donc nécessaire de développer de nouveaux modèles permettant d’incorporer coûts physiologiques et génétiques. Nous proposons ensuite une méthode vectorielle de construction d’un tel type de modèle, que nous appelons Matrice de Projection de Population Multitrait (MPPM). Ce dernier peut implémenter chaque type de coût en l’intégrant dans la matrice en tant que trait. Nous étendons ensuite aux MPPMs les techniques d’analyse de sensibilité, standards en démographie évolutive, des modèles à un trait aux MPPMs. Surtout, nous décrivons un nouvel outil d’analyse, pertinent en théorie des histoires de vie et en démographie évolutive: la Trait Level Analysis. Elle consiste à comparer des modèles qui partagent les mêmes propriétés asymptotiques. Ceci est rendu possible par le repliement d’une MPPM selon certains traits, une opération qui réduit le nombre de traits du modèle en moyennant ses transitions selon les abondances ergodiques relatives. Ainsi, la Trait Level Analysis permet de mesurer l’importance évolutive des coûts de la reproduction en comparant des modèles implémentant ces coûts, avec des versions ergodiquement équivalentes de ces modèles mais repliées selon les traits supportant les compromis. Nous utilisons des méthodes, classiques et nouvelles, de calculs des moments de la fitness – gradient de sélection, variance du succès reproducteur, variance environnementale – que nous appliquons aux modèles avec coûts et sans coûts afin de mesurer leurs effets démographiques et évolutifs. Nous présentons les effets conjoints des coûts physiologiques et génétiques sur la distribution par âge des taux vitaux d’une population. Nous montrons également comment les coûts physiologiques influencent les deux composants de la sélection efficace, en aplatissant le gradient de sélection d’un côté et en accroissant la taille efficace de la population de l’autre. Enfin, nous démontrons comment l’effet tampon des coûts sur les variances environnementales et démographiques améliore la résilience d’une population soumise aux coûts physiologiques de la reproduction / Costs of reproduction are pervasive in life history theory. Through this constraint, the reproductive effort of an organism at a given time negatively affects its later survival and fertility. For life historians, they correspond mostly to a physiological trade-off that stems from an allocative process, occurring at each time-step, at the level of the individual. For evolutionary demographers, they are essentially about genetic trade-offs, arising from a genetic variance in a pleiotropic gene acting antagonistically on early-age and late-age fitness components. The study, from an evolutionary demographic standpoint, of these mechanisms and of the relative, cross and joint effects of physiological and genetic costs, is the aim of this thesis. The close examination of Williams (1966)’s original definition of the physiological costs of reproduction led us to produce a theoretical design of their apparatus that accounts for both their mechanistic and evolutionary mechanisms. This design allowed us to make predictions with regards to the strength of costs of reproduction for various positions of organisms on three life-history spectra: slow-fast, income-capital breeders and quality-quantity. From Stearns (1989b)’s tryptic architecture of life history trade-offs –that divides their structure into the genotypic level, the intermediate structure and the phenotypic level – we devised a general framework, which models the possible cohabitation of both physiological and genetic costs. From this, we inferred differing detectability patterns of both types of costs according to the environmental conditions, their variance and individual stochasticity. We could also establish that both costs buffer environmental variations, but with varying time windows of effect. Their dissimilarity emerges also from the differences between mathematical projection models specific to each cost. A new family of evolutionary models is therefore required to implement both physiological and genetic trade-offs. We then describe the vector-based construction method for such a model which we call Multitrait Population Projection Matrix (MPPM) and which allows incorporating both types of costs by embedding them as traits into the matrix. We extend the classical sensitivity analysis techniques of evolutionary demography to MPPMs. Most importantly, we present a new analysis tool for both life history and evolutionary demography: the Trait Level Analysis. It consists in comparing pairs of models that share the same asymptotic properties. Such ergodic equivalent matrices are produced by folding, an operation that consists in reducing the number of traits of a multi-trait model, by averaging transitions for the traits folded upon, whilst still preserving the asymptotic flows. The Trait Level Analysis therefore allows, for example, to measure the evolutionary importance of costs of reproduction by comparing models incorporating them with folded versions of these models from which the costs are absent. Using classical and new methods to compute fitness moments – selection gradient, variance in reproductive success, environmental variance - in models with and without the costs, we can show their effects on various demographic and evolutionary measures. We reveal, in this way, the combined effects of genetic and physiological costs on the vital rates of an age-structured population. We also demonstrate how physiological costs affect both components of effective selection, as they flatten the slope of selection gradients and increase the effective size of a population. Finally, we show how their buffering of environmental and demographic variance confer greater resilience to populations experiencing physiological costs of reproduction