Les radiations évolutives sont des phénomènes de diversification rapide, et une source majeure de la diversité biologique sur Terre. J'explore ici l'hypothèse selon laquelle les mécanismes écologiques et génétiques à la base des radiations évolutives structurent les patrons macroécologiques et macroévolutifs de diversité. Pour ce faire, j'analyse les prédictions de plusieurs modèles de radiation émergeant des dynamiques spatio-temporelles à l'échelle individuelle. Ces analyses montrent d'abord que la structuration spatiale est un facteur majeur de diversité et d'endémisme au sein des archipels océaniques, en raison d'interactions entre dispersion et spéciation allopatrique. L'intégration de la dynamique des paysages et des processus d'interactions compétitives révèle ensuite comment ces facteurs se combinent pour structurer la forme des arbres phylogénétiques, et notamment générer des arbres déséquilibrés et une décélération du tempo de branchement, souvent observés dans les phylogénies moléculaires. J'explore alors les mécanismes responsables de cette décélération. Je montre qu'elle reflète une diversité-dépendance négative du taux de spéciation, liée à une réduction de la persistance et différentiation écologique des nouvelles populations. Le taux d'extinction n'est lui pas influencé par la diversité, les extinctions étant ici surtout causées par une combinaison d'exclusion compétitive et d'hybridation d'espèces incipientes. Enfin, je mets en évidence l'importance, lors d'une crise d'extinction, de la topologie rangée des arbres phylogénétiques et de la distribution des extinctions sur les pertes de diversité phylogénétique, et donc sur le potentiel d'évolution future. / Evolutionary radiations are phenomena of rapid diversification, and one of the major sources of biodiversity on Earth. Here, I explore the hypothesis that ecological and genetic mechanisms underpinning evolutionary radiations structure macroecological and macroevolutionary patterns of diversity. To this end, I analyse the predictions of several models in which radiations emerge from spatio-temporal dynamics at the scale of the individual. These analyses first show that spatial structure is a major driver of diversity and endemism on oceanic archipelagos due to interactions between dispersal and allopatric speciation. Second, by integrating landscape dynamics and the processes of competitive interactions, I reveal how these factors combine to shape phylogenetic trees, and in particular to beget trees that are unbalanced and exhibit a deceleration in branching tempo, which is often observed on molecular phylogenies. I then explore the mechanisms responsible for this deceleration. I show that it reflects a negative diversity-dependence of the speciation rate, itself linked to a reduction in the persistence and ecological differentiation of new populations. The extinction rate is, on the other hand, uninfluenced by species diversity, extinctions being here mainly caused by a combinaison of competitive exclusion and hybridization of incipient species. Finally, I show that during mass extinctions the ranked topology of phylogenetic trees and the distribution of extinctions among the tips have a strong impact on the loss of phylogenetic diversity, and hence on the potential for future evolution.

The broad concept of 'biodiversity' can be roughly separated into two related components: trait diversity and species richness. Despite the fact that one or both of these types of biodiversity underlie much of ecology, evolution, and conservation, however, it remains largely unknown how traits and speciation dynamics can interact, particularly at a large scale. My thesis uses modern phylogenetic comparative methods and a new global database of avian morphological traits to quantify and predict the drivers of biodiversity across the world's birds, focusing particularly on the relative roles of ecological and social traits to understanding broad evolutionary patterns. In Chapter 2 I present a survey of avian functional traits, focusing on eight measurements of the beaks, wings, tails, and tarsi of 42,334 individuals representing 10,023 extant and recently extinct species. The global trait distribution of avian communities is consistent with a competition-based model of community assembly, and I find no evidence of environmental filtering at the biome level. The traits exhibited within avian orders tend to become more dissimilar as species richness increases, with the notable exception of the Passeriformes, an order containing around 60% of the total avian species richness but occupying a region of morphospace expected of a clade two orders of magnitude smaller. The Passeriformes also possess remarkable vocal morphology and behavior, and thus I spend the next three chapters of this thesis focused on the role of social processes in avian evolution. In Chapter 3, I use detailed morphological and vocal trait data from the suboscine family Furnariidae to demonstrate that social traits evolve faster and with less regularity than ecological traits. I then in Chapter 4 examine the social and ecological drivers of female song in birds, a widespread trait whose persistence challenges traditional sexual selection theory. I find that the separate drivers of male and female song can be explained by social selection theory, a framework which encompasses all social interactions above and beyond competition for mating opportunities. In Chapter 5 I apply this concept of social selection to macroevolutionary studies, using sex-specific song behaviors to separately investigate the roles of social and sexual selection on speciation and extinction rates. I demonstrate that lineages with male-only song (sexual selection) diversify faster than lineages with both male and female song (social selection). This result suggests that social selection theory may inform the controversial relationship between sexual selection and diversification. Finally, in Chapter 6 I look at the role of dispersal in modulating these speciation and extinction rates. Using data from the wing morphologies of 26,043 individuals from 6,028 species, I test the 'intermediate dispersal hypothesis', hitherto only examined at small scales, across the order Passeriformes, revealing that the highest rates of diversification are indeed found in lineages with an intermediate capacity for flight. When birds that defend year-round territories are considered separately from non-territorial birds, however, the intermediate dispersal hypothesis only holds for territorial birds, demonstrating the importance of considering the ecological context of traits in macroevolutionary studies. Together, my results present evidence that both social and ecological processes facilitate the generation and maintenance of biodiversity in birds.

Habitat modification alters species' capacities to track shifting climatic conditions. Broad-scale analyses that explore demographical responses to on-going climate change tend to neglect the influence of the underlying landscape pattern. However, many landscapes are fragmented by human activities, which might make dispersal for many species more challenging. Determining the extent to which landscape factors affect broad-scale distributional patterns has implications for our ability to predict realistic climate change impacts on species. Here, we constructed species-specific measurements of landscape permeability for 96 butterfly species in southern Ontario to test whether this landscape characteristic affected species' distributions at macroecological scales. We used multiple logistic regression models to test for the effects of permeability and its interaction with temperature on butterfly species presence/absence. We found that 48% of butterfly species responded to landscape permeability alone or in interaction with temperature. In general, the effect was positive (87%) and species were more likely to be present with increasing landscape permeability. For 61% of the species that responded to broad-scale landscape permeability, the interaction of temperature with permeability was statistically significant. In warm areas, species were more likely to be present if landscape permeability was high. Landscape permeability explained 3-43% of residual variability in species' presences after accounting for temperature. Finally, we show how fine-scale permeability measurements can be combined with large-scale patterns of diversity to inform conservation efforts. Landscape permeability can affect species' distributions at broad-scales and understanding factors that potentially influence species' dispersal can improve predictions for how species respond to changing climatic conditions.

Aim It is commonly asserted that climate presents the primary constraint on species’ geographic distributions, and therefore, that species' ranges shift in response to changing climate given their specific climatic tolerances. However, supporting evidence is surprisingly inconsistent. Alternatively, spatially structured processes (e.g., dispersal) could more strongly determine species’ geographic distributions. Is climate the primary determinant of species’ geographic distributions, or might non-climatic, spatial processes constitute a stronger influence, such that the effect of climate is indirect? This study tests a number of predictions made by each of these hypotheses, during a single period of time. Location Contiguous United States and southern Canada. Methods We used 19 species of passerine birds whose distributions fall entirely within the area sampled by the North American Breeding Bird Survey from 1990-2000. We related these distributions to the mean breeding season climate, geographic locations and neighbourhood effects. Two spatial scales were addressed to assess the geographic location of species’ ranges and species' distributions within ranges. Results On average, geographic coordinates and a model representing neighbourhood occupancy outperform a simple climatic model. After controlling for geographic coordinates, species occupancy is poorly related to climate. A neighbourhood model on average accounts for the majority of variance captured by geographic coordinates within ranges, and more for the continental placement of ranges. Spatially explicit variables are more important than macroclimatic variables in a predictive model of species occupancy on average. Main Conclusions The geographic distributions of wide-spread North American passerine birds appear not to be primarily determined by climate. Our results are consistent with the hypothesis that localized spatial processes such as dispersal are stronger determinants of both continental range placement and within-range distributions of North American birds.

The Amazon River drainage basin is known as the most biodiverse region in the world. Regarding freshwater fish, this region contains around 15% of the world's fish richness. The fish family Serrasalmidae have a variety of feeding preferences including Pacus (herbivores) and Piranhas (carnivores). Fruit eating fish species are evolutionarily the oldest species in the family and have a mutualistic interaction with flooded forests. Considering the diversity of feeding habits of the Serrasalmidae family, it represents an excellent model to study ecological questions related to factors that influence the spatial distribution of species and factors that contribute to the maintenance of biodiversity. I first analyzed how differences in dietary preferences influence the spatial distribution and habitat associations of species at the landscape scale using diet data and three proxies of habitat association derived from satellite products. Using Phylogenetic Generalized Least Squares models I evaluated the relationship between habitat association and feeding guilds. Differences in resource distribution (assessed through feeding guilds) can influence habitat associations. Considering the hydrological variability (i.e., floodplain extent) and landscape heterogeneity that characterize floodplains, the patterns of habitat association vary with the spatial scale considered. Second, I identified factors that aid in sustaining aquatic biodiversity in floodplain forests of the Amazon River basin, focusing on frugivorous fish. I used descriptors of the floodplain ecosystem- and landscape-level variables to assess their contribution to the maintenance of fish species richness. Using Generalized Linear Models (GLM) with negative binomial distribution I found that greater plant richness could offer a greater variety of food resources for frugivorous fishes and that a more extensive floodplain area provides larger forested habitat for fishes that depend on forest-derived food resources, as such subbasins with these characteristics support a greater frugivorous fish species richness. This work provides valuable information on species habitat associations by fish as well as food resource dynamics, floodplain dependence, and advances our understanding of the intricate relationship between forests and fish at a basin scale. This information is critical for assessing the impact of anthropogenic activities on freshwater ecosystems and can be used to inform conservation strategies in the tropics.

No description available.

The destruction and fragmentation of natural habitat is the leading driver of the current extinction crisis. As a result, a research area has emerged focused on studying ecology in islands of natural habitat surrounded by a sea of anthropogenic land uses, so called ‘habitat islands’. However, this research has largely been undertaken on small-medium scales, generally in single systems. Furthermore, many habitat island studies have used previous results and theory derived in the context of oceanic island research. Thus, this thesis aims to examine a variety of macroecological and biogeographical patterns using a large number of purely habitat datasets sourced from both the literature and my own sampling, with the objective of teasing out any general statistical patterns. The various macroecological and biogeographical patterns can be grouped under four broad headings: 1) species–area relationships (SAR), 2) nestedness, 3) species abundance distributions (SADs), and 4) species incidence functions (function of area). Overall, it was found that there were few hard macroecological generalities that hold in all cases across habitat island systems. This is because most habitat island systems are highly disturbed environments, with a variety of confounding variables and undesirable species (e.g. species associated with human land uses) acting to modulate the patterns of interest. Nonetheless, some clear patterns did emerge. In particular, it was found that the power model was by the far the best general SAR model for habitat islands. The slope of the island species–area relationship (ISAR) was related to the matrix type surrounding archipelagos, such that habitat island ISARs were shallower than true island ISARs. Significant compositional and functional nestedness was rare in habitat island datasets, although island area was seemingly responsible for what nestedness was observed. Species abundance distribution models were found to provide useful information for conservation in fragmented landscape, but the presence of undesirable species substantially affected the shape of the SAD. Species incidence function curves were found to vary across space for a given species, but not in any systematic manner. In conclusion, this thesis finds that the application of standard island biogeography theory to habitat islands is too simplistic. It is hoped that the results of this thesis will act as a catalyst for a more macroecological approach to habitat island research, and a starting point for the development of an integrated theory of habitat islands.

La diadromie représente un cycle de vie qui implique obligatoirement des migrations entre la mer et l’eau douce. La diadromie s’est maintenue dans différentes lignées évolutives de poissons, mettant ainsi en évidence l’existence d’avantages adaptatifs comme la capacité à coloniser des milieux vierges ou de mieux exploiter la variabilité spatio-temporelle de l’environnement. Une hypothèse pour expliquer l’origine et le maintien de la diadromie postule que les migrations entre mer et rivière ont pour but de placer les individus dans le milieu qui favorisera la croissance avant la première reproduction. Une croissance en mer et une reproduction en rivière (anadromie) serait favorisée si la productivité primaire en eau douce est inférieure à celle des milieux marins environnants tandis que la situation inverse (catadromie ; reproduction en mer, croissance en rivière) est attendue quand le différentiel de productivité est en faveur des eaux douces. Les résultats de notre étude réalisée à l’échelle du globe confirment cette hypothèse et montrent également que les poissons diadromes se trouvent majoritairement dans des rivières à faible richesse spécifique et/ou ouvertes à la colonisation après le retrait des glaciers au Quaternaire. Leur capacité à coloniser de nouveaux milieux permet aux diadromes d’être très présents sur les îles océaniques. Si la biodiversité sur les îles océaniques a été largement étudiée, très peu d’études ont porté sur les poissons d’eau douce qui s’y trouvent. Notre étude des peuplements de poissons des îles polynésiennes confirme la généralité d’un modèle proposé pour les faunes terrestres prédisant une relation en dôme entre richesse spécifique et âge de l’île. Nos résultats montrent également que la richesse diminue avec la distance au centre de biodiversité le plus proche et augmente avec l’altitude maximale de l’île.Malgré leur succès évolutif, les poissons diadromes se révèlent très vulnérables face aux activités humaines (surexploitation, pollution de l’eau, barrages…). De ce fait, de nombreuses espèces sont classées comme vulnérables par l’IUCN. Paradoxalement, notre étude sur les caractéristiques biologiques et écologiques des espèces qui se sont éteintes récemment à l’échelle du globe n’identifie pas la diadromie comme un facteur aggravant. Cette étude montre que le critère biologique principal menant à l’extinction est l’endémisme et une aire de distribution géographique restreinte. Bien que souvent en déclin, beaucoup d’espèces diadromes ont jusqu’ici échappé à l’extinction du fait de leur aire de distribution initiale de grande taille, résultat probable de leur grande capacité de dispersion. Un très bon exemple est l’esturgeon européen, Acipenser sturio, initialement largement distribué en Europe mais qui après un fort déclin à partir de 1850 ne se reproduit plus que dans le seul bassin de la Garonne. Pour mieux suivre le déclin de cette espèce au cours du temps, nous avons étudié sa distribution avant 1850 à l’aide de données archéozoologiques. L’analyse de ces données suggère une diminution des populations très ancienne, initiée il y a 2500 ans. A l’aide de températures passées reconstituées, nous avons montré que des températures élevées expliquent en partie l’occurrence d’esturgeons dans les sites archéologiques mais sans contribuer à expliquer son déclin. Ces résultats suggèrent un impact de l’homme précoce sur les populations d’esturgeons. Cette thèse a permis de synthétiser les connaissances sur les poissons diadromes concernant leur distribution géographique à diverses échelles de temps et d’espace, et de contribuer à une meilleure compréhension de leur diversité et de leur vulnérabilité. / Diadromous species exhibit a life-cycle implying migrations between freshwater and ocean. Diadromy is observed in many fish lineages suggesting that adaptive traits are associated with this strategy such as better dispersal ability and more efficient tracking of the spatio-temporal variability of the environment. One of the hypotheses that have been put forward to explain the evolution and persistence of diadromy states that the purpose of migrations is to select environmental conditions that will optimize pre-reproductive growth. Growing at sea and reproducing in river (anadromy) is supposed to be favored when freshwater primary productivity is lower in freshwater than in the nearby sea. The reverse (growing in freshwater, reproducing in ocean; catadromy) is expected when productivity is higher in sea than in freshwater. According to our study, conducted at a global scale, this hypothesis holds true. In addition it is shown that diadromous species are overrepresented in species poor rivers and/or in those that have been open to colonization after the retreat of glaciers after the last glacial maximum. Because of their dispersal ability, diadromous species are also over-represented on oceanic islands. Biodiversity on islands is classical topic of biogeography but yet few studies have dealt with freshwater fishes. In our study of fish communities from the Polynesian islands, we demonstrate the generality of a model initially built to explain terrestrial biodiversity on oceanic islands. As predicted by this model, species richness peaks at peaks at intermediate island age. Also revealed by our results are a positive relationship between island elevation and species richness and a decrease in species richness as the distance from the nearest biodiversity hotspot increases. Diadromy has been a successful strategy over geologic times but in face to human activities it seems to contribute to extinction proneness, as exemplified by the numerous diadromous species red listed by IUCN. Paradoxically, our study about the biological and ecological traits shared by the freshwater fishes that have been recently globally extinct does not suggest that diadromy has been a major factor. This study points to endemism and restricted geographic range size as the major determinants of extinction. It seems that because of their dispersal abilities, diadromous species tend to have widespread historical distributions and, even if many species are declining, this prevented most of them from being entirely extirpated. This is well exemplified by the European sturgeon (Asipenser sturio), formerly widely distributed over Europe and now restricted to one reproducing population in the Garonne River, because of dramatic population collapses after 1850. To have a better idea of the fate of this species before 1850, we analyzed archaeozoological records. According to our analyses, sturgeons started to decline a long time ago, about 2500 years ago. Using reconstructed past temperatures, our analyses show that a high temperature increases the probability of finding this species in archeological remains but cannot explain entirely the observed decline. This suggests that human activities impacted sturgeon populations well before the industrial revolution. This thesis by synthesizing species occurrence data over different spatial and temporal scales contributed to a better knowledge about the diversity and vulnerability of diadromous fishes.

In natural systems, it has been observed that plankton exist in patches rather than in an even distribution across a body of water. However, the mechanisms behind this patchiness are not fully understood. Several previous modeling studies have examined the effects of abiotic and biotic factors on patch structure. Yet these models ignore a key point: zooplankton often undergo diel vertical migration. I have formulated a model that incorporates vertical movement into the Rosezweig-MacArthur (R-M) predator-prey model. The R-M model is stable only at a carrying capacity below a critical value. I found that adding vertical movement stabilizes the system even at a high carrying capacity. By analyzing temporal stability and spatial structure, my results show that vertical movement interacts with carrying capacity to determine patch structure. / by Simantha Ather. / Thesis (M.S.)--Florida Atlantic University, 2009. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2009. Mode of access: World Wide Web.

abstract: Rapidly growing research on mothers’ perinatal depression, has demonstrated significant links among mothers’ depressive symptoms during pregnancy and the first year postpartum, their parenting, and multiple aspects of children’s development. This prospective longitudinal study contributes to research on mothers’ perinatal depression by examining the mechanisms by which maternal perinatal depression is associated with children’s adjustment early in development in a sample of 204 Mexican-origin adolescent mothers (Mage at Wave 1 = 16.80, SD = 1.0) and their children (58% boys). I expected that adolescent mothers’ negative parenting behaviors would mediate the associations between mothers’ perinatal depressive symptoms and three child outcomes: internalizing symptoms, externalizing behaviors, and cognitive ability. I further hypothesized that mothers’ perceived social support from their family would modify the extent to which mothers’ perinatal depressive symptoms negatively impact their parenting behaviors and their children’s developmental outcomes. Mothers reported on their own depressive symptoms, their perceived social support from their family and their children’s internalizing and externalizing problems; negative parenting was assessed using observational methods; and children’s cognitive ability was assessed using standardized developmental assessments. In this sample, adolescent mothers’ negative parenting behaviors did not significantly mediate the relations between mothers’ perinatal depression and children’s developmental outcomes. Further, perceived social support did not significantly buffer the effects of mothers’ perinatal depression on mothers’ negative parenting or children’s developmental outcomes. However, in line with hypotheses, results indicated that mothers’ prenatal depression had a wider impact on children’s adjustment outcomes than mothers’ postpartum depression, which appeared more specific to children’s internalizing problems. Discussion focuses on implications for intervention addressing adolescent mothers’ perinatal depression, as well as the need to continue to explore protective factors that have the potential to disrupt the negative intergenerational transmission of risks. / Dissertation/Thesis / Doctoral Dissertation Family and Human Development 2019