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Européenne, (Anguilla anguilla) a conduit à une diminution du nombre d’anguille jaune dans les bassins versants. En 2007, le règlement (CE) instaure que 60% des civelles pêchées (<12 cm de long) doivent être dédiés à des opérations de repeuplement. Cependant, pour migrer et coloniser un nouvel environnement, les civelles doivent avoir une bonne condition énergétique. Or, les civelles ne s’alimentent pas ou peu durant leur migration estuarienne et la vitesse d’utilisation de leurs réserves dépend de divers facteurs (température, contaminants etc.). Dans l’estuaire de l’Adour, différents travaux ont mis en évidence de fortes concentrations en methylmercure (MeHg) dans les sédiments et une bioaccumulation de ce composé chez l’anguille jaune. L’exposition au MeHg entraîne la mise en place de processus de détoxication qui pourraient être couteux en énergie ce qui, chez des organismes jeûnant comme les civelles, conduirait à une perte de poids pouvant affecter leurs capacités de migration. Pour étudier l’impact du méthylmercure sur le potentiel de migration des civelles, nous avons tout d’abord (1) effectuer un état des lieux des concentrations en MeHg des civelles de l’estuaire de l’Adour, (2) évaluer l’effet du MeHg sur deux synchroniseurs de la migration estuarienne: le signal crépusculaire et l’alternance des marées chez les civelles grâce à l’utilisation de traceurs isotopiques et (3) étudier dans le milieu naturel (Adour) le comportement de migration, les taux de contamination au mercure et les mécanismes de détoxication des civelles. Nos résultats montrent des fluctuations temporelles et saisonnières de la concentration en MeHg des civelles prélevées en entrée et en milieu de l’estuaire. Par ailleurs, l’exposition au MeHg, en milieu contrôlé, a augmenté l'activité des civelles mais pas leur comportement de migration. Cependant, suite à la contamination, la structure mitochondriale et le métabolisme ont été modifiés suggérant un plus fort stress oxydant et une activation des défenses antioxydantes notamment des civelles ayant un faible potentiel de migration (non migrantes).En complément, l’étude en milieu naturel a mis en évidence une plus forte demande énergétique pour les civelles non migrantes entrainant une augmentation du fonctionnement des mitochondries et pouvant conduire à un plus fort stress oxydant. / Over the last three decades, the arrival of Anguilla anguilla glass eels has markedly declined which has lead to a decrease in the number of yellow eels in the watersheds. In 2007, the Regulation (EC) indicated that 60% of glass eels (<12cm long) caught by fisheries should be used for restocking. To migrate and colonize a new environment, glass eels must have a good energetic condition. However, during their estuarine migration, glass eels either feed very little or more likely not at all. The speed at which they expend their energy stores depends on various factors (temperature, contaminants etc.). In the Adour estuary, many studies have reported relatively high methylmercury (MeHg) concentrations in the sediments, and bioaccumulation in yellow eels. Exposure to MeHg requires energy for detoxification which, in starving organisms such as glass eels, might lead to weight loss, decreasing their ability to migrate up the estuary. To study the impact of MeHg on migratory behaviour in glass eels, we first conducted an inventory of MeHg concentrations of glass eels in the estuary of the Adour, (2) evaluate the effect of MeHg on two synchronizers of estuarine migration: dusk and tide on glass eels through the use of isotopic tracers and (3) to study the natural environment (Adour) migratory behavior, mercury contamination levels and detoxification mechanisms of glass eels. Our results show temporal and seasonal fluctuations in the concentration of MeHg glass eels collected input and middle of the estuary. Moreover, MeHg exposure, in a controlled environment, increased the activity of glass eels but not in response to migratory behavior. However, due to contamination, mitochondrial structure and metabolism have been modified suggesting a stronger oxidative stress and activation of antioxidant defences of glass eels, particularly those with low migration potential (non-migrant). In addition, the wild study showed a higher energy demand for non-migrating glass eels causing an increase in mitochondrial function which may lead to higher oxidative stress.

A família Accipitridae representa uma das maiores radiações de aves atuais, ocupando habitats diversos em grande parte do planeta. Entre as divisões propostas para a família no passado, o grupo dos gaviões buteoninos figura entre um dos poucos que se aproximam em composição a uma linhagem monofilética, de acordo com análises filogenéticas recentes. Além de ocorrer tanto no Novo Mundo como no Velho Mundo, a maior parte das espécies de gaviões buteoninos está concentrada na América do Sul e na América Central, o que os torna um modelo atrativo para a análise de padrões e processos de diversificação em escalas continental e local. Outro aspecto interessante do grupo é o grande número de espécies migratórias, padrão ainda pouco explorado sob uma perspectiva filogenética. Os principais objetivos deste trabalho foram inferir as relações filogenéticas entre as espécies de gaviões buteoninos, analisar a evolução do comportamento migratório no grupo, e inferir padrões e processos de diversificação, com ênfase na região Neotropical. Foram utilizados mais de 7.000 pares de base de DNA mitocondrial e nuclear de 51 espécies de gaviões buteoninos, compreendendo o maior estudo filogenético do grupo até o momento. Do total de seqüências utilizadas, cerca de um terço foi representado por seqüências de DNA do 12S, tRNAVal e 16S, que contém uma proporção de sítios de evolução dependente resultante da existência de uma estrutura secundária. Como forma de avaliar o impacto destes sítios nas estimativas, foram também realizadas análises alternativas que incorporaram informação de estrutura secundária. Devido à indisponibilidade de um modelo de estrutura secundária de 16S para aves, este foi aqui elaborado com base em uma análise comparativa de representantes de todas as ordens de aves atuais. Os resultados sugerem que os gêneros Buteo, Leucopternis e Buteogallus como atualmente reconhecidos não são monofiléticos, o que ressalta a falta de concordância entre a classificação atual e a histórica evolutiva do grupo. Cinco linhagens principais foram encontradas, sendo a base da árvore composta por espécies predominantemente neotropicais, e a porção mais derivada principalmente por espécies neárticas e do Velho Mundo. Este resultado, associado às estimativas de tempo de divergência, sugere um longo período de diversificação na região Neotropical (com início entre o Oligoceno Superior ou o Mioceno, e se estendendo até o Pleistoceno), com colonização e diversificação recentes na região Neártica e no Velho Mundo (com início no Mioceno Superior ou no Plioceno, se estendendo até o Pleistoceno). O comportamento migratório evoluiu diversas vezes, e pode ter contribuído para a diversificação de algumas espécies, ao possibilitar a colonização de habitats antes não ocupados e promover especiação em ilhas. Na região Neotropical, disjunções de espécies de florestas de terras baixas que ocupam áreas a leste e oeste dos Andes ocorreram quatro vezes, possivelmente em dois eventos vicariantes. As disjunções mais antigas podem ter sido causadas pelo soerguimento da cordilheira, enquanto não foi possível definir claramente os processos envolvidos nas especiações mais recentes. Foram encontradas duas linhagens distribuídas em habitats alagados e ripários. Os resultados sugerem não somente um longo processo de diversificação, de forma independente das espécies de florestas não alagadas, mas também conexões históricas entre florestas de várzea da Amazônia e habitats costeiros. Espécies florestais e de áreas abertas não são reciprocamente monofiléticas. De forma similar, em alguns casos, espécies pertencentes a um mesmo bioma não são proximamente relacionadas, o que sugere uma história complexa de diversificação na região. A utilização de dados de sítios emparelhados de seqüências de RNA não trouxe mudanças significativas nas topologias e inferências de tempo de divergência, possivelmente devido à baixa variação das hastes neste grau de divergência. / The family Accipitridae represents one of the largest radiations of modern birds, with species being found in a plethora of habitats around the world. Among the divisions proposed for the family in the past, the group of the buteonine hawks is one of the few that approximate monophyletic lineages, according to recent phylogenetic analyses. Besides occurring both in the New World and Old World, most buteonine hawk species are mainly found in Central and South America, what provides an opportunity to evaluate patterns and processes of diversification in both continental and local scales. The main goals of this work were to infer phylogenetic relationships among species of buteonine hawks, analyze the evolution of migratory behaviour, and evaluate patterns and processes of diversification, especially in the Neotropical region. We obtained more than 7.000 base pairs of mitochondrial and nuclear DNA sequences from 51 species of buteonine hawks, what comprises the largest phylogenetic analysis of the group so far. Approximately one third of the total dataset was obtained from DNA sequences of 12S, tRNAVal and 16S, which are known to have paired sites that evolve in concert due to the presence of a secondary structure. Alternative analyses incorporating such information have been performed, as a way to evaluate the effects of secondary structure in the phylogenetic analyses. Since a model of secondary structure of 16S of birds was not available so far, we build one based on comparative analysis of representatives of all modern avian orders. The results suggest that the genera Buteo, Leucopternis and Buteogallus as currently accepted are not monophyletic, what stress a lack of concordance between current classification and the evolutionary history of this group. Five main lineages were found, and the most basal part of the topology is composed by mainly neotropical species, while the majority of neartic and Old World species were positioned in the most derived part of the tree. Together with divergence time estimates, those results suggest a long period of diversification in the Neotropics (possibly beginning in the Upper Miocene or Oligocene, and extending to the Pleistocene), with a latter colonization and diversification of the Neartics and Old World (possibly beginning between the Upper Oligocene or Pliocene, and extending to the Pleistocene). Migratory behaviour evolved several times, and may have contributed to diversification by means of exploitation of previously unavailable habitats as well as promotion of speciation in islands. Lowland species disjunctions between each side of the Andes occurred four times, possible due to two vicariant events. The earliest disjunctions may have been caused by Andean orogeny, but no process could be clearly attributed to the two most recent speciations. Two lineages restricted to flooded habitats were found. The results suggest not only a long process of diversification in such habitats, independently of species of non-flooded habitats, but also a historical relationship between várzea forests in Amazonia and costal habitats. Similarly, species that occupy the same biome are not the closest relatives in several cases, what suggests a complex history of diversification in the Neotropical region. Inclusion of secondary structure information did not affect significantly phylogenetic and divergence time estimates, likely due to the low variation in stems in such level of divergence.

The propensity for animals to migrate can vary markedly among species, populations within species, and individuals within populations. Many taxa displaying variation in migratory behaviour and life history are attracting conservation concern as migratory populations decline in abundance. I developed a conceptual framework for delineating the nature of the broad phenotypic variation observed among and within migratory populations and apply this to Lake Superior brook trout (Salvelinus fontinalis). My literature review of variation in the migratory behaviour of fishes revealed that subsets of the predictions outlined in my framework have been tested for most study systems, but few systems had tested all five predictions. My field studies of Lake Superior brook trout (i) compared isotopic signatures of brook trout sampled from Lake Superior and tributary streams to demonstrate that the fish sampled from the lake and stream differ consistently in habitat use and trophic ecology, (ii) applied age and growth analyses to demonstrate that fish sampled from the lake live longer and grow faster than fish sampled from the streams, with the differences in growth apparent by the end of the first year of life, (iii) used histological measures to demonstrate that fish residing in streams, and exhibiting a stream growth history, reach sexual maturity, and (iv) provided no evidence based on growth histories to suggest that individuals change migratory behaviours later in life. Together, these field studies suggest that partial migration is the best hypothesis to describe the variation observed in the migratory behaviour of brook trout in the Nipigon Bay area of Lake Superior. Although the possibility remains that some individuals could complete their life cycle in the lake. My review and field studies demonstrate that the conceptual framework can be used to help delineate variation in the migratory behaviour exhibited by fishes whose lifetime movements can be difficult to track. / Funding was provided by the Ontario Ministry of Natural Resources through the Canada-Ontario Agreement Respecting the Great Lakes Basin Ecosystem, Great Lakes Fishery Commission Fishery Research Program, a Natural Science and Engineering Research Council (NSERC) Postgraduate Scholarship, and a NSERC Discovery Grant.

This thesis evaluates the adaptive significance of annual cycles on the migratory behaviour of Baltic salmon (Salmo salar L.). The studies have included field experiments as well as laboratory studies gf maturity and migratory behaviour patterns of smolts and postsmolts mainly from the Angerman river population. Contrasting to the phenotypical elasticity in life-history traits, Baltic salmon was found to have a rather strict temporal organization of their annual behavioural patterns. Two year old smolted Baltic salmon showed drastic differences in migratory behaviour when compared in tanks containing either fresh or brackish water. Freshwater kept fish showed an annual cycle where downstream displacement in the upper water column was followed by a stationary behaviour, indicating a readaption to a freshwater life. Fish in brackish water behaved as a migratory fish throughout tne study. Baltic salmon also showed differences in maturation patterns in fresh and brackish water. Three summer old males detained in freshwater all matured sexually the following autumn. If transferred to sea and kept in net- pens a low proportion matured, mainly previously matured males. Furthermore there was a size- dependent relationship of sexual rematuration. Many small previously matured males did not migrate, similarly small previolusly matured males were unable to respond to shifts in the environment. With larger size the alternatives of sexual maturation and high growth rate wi more related to the environmental conditions the fish experienced. A hypothesis has been tested assuming that Baltic salmon migration is influenced by an annual time program. According to the hypothesis the migratory distance covered in the Baltic should be a result of a migratory activity sequence rather than a definite goal orientation. Fish detained before release generally showed a shorter distance between release point and area of recapture compared to fish released at normal time of smoltrun. The migratory distance appeared to be inversly related to the period of delay before release. A seasonal difference in migratory propensity was recorded. An instantaneous mortality curve for Baltic salmon during seaward migration and early sea-phase was estimated based on recapture data on sequentially related fish. The weekly mortality rate decreased from an initial mean of 271 during onset of migration, to 3.51 in mean during autumn. The high risk of mortality during the first part of migration indicated that strong selective forces act on a precise seasonal timing of migration. / <p>Diss. (sammanfattning) Umeå : Umeå universitet, 1988, härtill 5 uppsatser</p> / digitalisering@umu

A família Accipitridae representa uma das maiores radiações de aves atuais, ocupando habitats diversos em grande parte do planeta. Entre as divisões propostas para a família no passado, o grupo dos gaviões buteoninos figura entre um dos poucos que se aproximam em composição a uma linhagem monofilética, de acordo com análises filogenéticas recentes. Além de ocorrer tanto no Novo Mundo como no Velho Mundo, a maior parte das espécies de gaviões buteoninos está concentrada na América do Sul e na América Central, o que os torna um modelo atrativo para a análise de padrões e processos de diversificação em escalas continental e local. Outro aspecto interessante do grupo é o grande número de espécies migratórias, padrão ainda pouco explorado sob uma perspectiva filogenética. Os principais objetivos deste trabalho foram inferir as relações filogenéticas entre as espécies de gaviões buteoninos, analisar a evolução do comportamento migratório no grupo, e inferir padrões e processos de diversificação, com ênfase na região Neotropical. Foram utilizados mais de 7.000 pares de base de DNA mitocondrial e nuclear de 51 espécies de gaviões buteoninos, compreendendo o maior estudo filogenético do grupo até o momento. Do total de seqüências utilizadas, cerca de um terço foi representado por seqüências de DNA do 12S, tRNAVal e 16S, que contém uma proporção de sítios de evolução dependente resultante da existência de uma estrutura secundária. Como forma de avaliar o impacto destes sítios nas estimativas, foram também realizadas análises alternativas que incorporaram informação de estrutura secundária. Devido à indisponibilidade de um modelo de estrutura secundária de 16S para aves, este foi aqui elaborado com base em uma análise comparativa de representantes de todas as ordens de aves atuais. Os resultados sugerem que os gêneros Buteo, Leucopternis e Buteogallus como atualmente reconhecidos não são monofiléticos, o que ressalta a falta de concordância entre a classificação atual e a histórica evolutiva do grupo. Cinco linhagens principais foram encontradas, sendo a base da árvore composta por espécies predominantemente neotropicais, e a porção mais derivada principalmente por espécies neárticas e do Velho Mundo. Este resultado, associado às estimativas de tempo de divergência, sugere um longo período de diversificação na região Neotropical (com início entre o Oligoceno Superior ou o Mioceno, e se estendendo até o Pleistoceno), com colonização e diversificação recentes na região Neártica e no Velho Mundo (com início no Mioceno Superior ou no Plioceno, se estendendo até o Pleistoceno). O comportamento migratório evoluiu diversas vezes, e pode ter contribuído para a diversificação de algumas espécies, ao possibilitar a colonização de habitats antes não ocupados e promover especiação em ilhas. Na região Neotropical, disjunções de espécies de florestas de terras baixas que ocupam áreas a leste e oeste dos Andes ocorreram quatro vezes, possivelmente em dois eventos vicariantes. As disjunções mais antigas podem ter sido causadas pelo soerguimento da cordilheira, enquanto não foi possível definir claramente os processos envolvidos nas especiações mais recentes. Foram encontradas duas linhagens distribuídas em habitats alagados e ripários. Os resultados sugerem não somente um longo processo de diversificação, de forma independente das espécies de florestas não alagadas, mas também conexões históricas entre florestas de várzea da Amazônia e habitats costeiros. Espécies florestais e de áreas abertas não são reciprocamente monofiléticas. De forma similar, em alguns casos, espécies pertencentes a um mesmo bioma não são proximamente relacionadas, o que sugere uma história complexa de diversificação na região. A utilização de dados de sítios emparelhados de seqüências de RNA não trouxe mudanças significativas nas topologias e inferências de tempo de divergência, possivelmente devido à baixa variação das hastes neste grau de divergência. / The family Accipitridae represents one of the largest radiations of modern birds, with species being found in a plethora of habitats around the world. Among the divisions proposed for the family in the past, the group of the buteonine hawks is one of the few that approximate monophyletic lineages, according to recent phylogenetic analyses. Besides occurring both in the New World and Old World, most buteonine hawk species are mainly found in Central and South America, what provides an opportunity to evaluate patterns and processes of diversification in both continental and local scales. The main goals of this work were to infer phylogenetic relationships among species of buteonine hawks, analyze the evolution of migratory behaviour, and evaluate patterns and processes of diversification, especially in the Neotropical region. We obtained more than 7.000 base pairs of mitochondrial and nuclear DNA sequences from 51 species of buteonine hawks, what comprises the largest phylogenetic analysis of the group so far. Approximately one third of the total dataset was obtained from DNA sequences of 12S, tRNAVal and 16S, which are known to have paired sites that evolve in concert due to the presence of a secondary structure. Alternative analyses incorporating such information have been performed, as a way to evaluate the effects of secondary structure in the phylogenetic analyses. Since a model of secondary structure of 16S of birds was not available so far, we build one based on comparative analysis of representatives of all modern avian orders. The results suggest that the genera Buteo, Leucopternis and Buteogallus as currently accepted are not monophyletic, what stress a lack of concordance between current classification and the evolutionary history of this group. Five main lineages were found, and the most basal part of the topology is composed by mainly neotropical species, while the majority of neartic and Old World species were positioned in the most derived part of the tree. Together with divergence time estimates, those results suggest a long period of diversification in the Neotropics (possibly beginning in the Upper Miocene or Oligocene, and extending to the Pleistocene), with a latter colonization and diversification of the Neartics and Old World (possibly beginning between the Upper Oligocene or Pliocene, and extending to the Pleistocene). Migratory behaviour evolved several times, and may have contributed to diversification by means of exploitation of previously unavailable habitats as well as promotion of speciation in islands. Lowland species disjunctions between each side of the Andes occurred four times, possible due to two vicariant events. The earliest disjunctions may have been caused by Andean orogeny, but no process could be clearly attributed to the two most recent speciations. Two lineages restricted to flooded habitats were found. The results suggest not only a long process of diversification in such habitats, independently of species of non-flooded habitats, but also a historical relationship between várzea forests in Amazonia and costal habitats. Similarly, species that occupy the same biome are not the closest relatives in several cases, what suggests a complex history of diversification in the Neotropical region. Inclusion of secondary structure information did not affect significantly phylogenetic and divergence time estimates, likely due to the low variation in stems in such level of divergence.

Cette recherche doctorale entend caractériser les fluctuations morphologiques des rennes paléolithiques du Sud-Ouest de la France consécutives aux changements climatiques. En effet, le dernier Pléniglaciaire et le Tardiglaciaire (entre 21 500 - 13 000 cal. BP) ont constitué des périodes de contraintes paléoclimatiques et paléoenvironnementales particulièrement fortes, qui ont occasionné, directement ou indirectement, des répercussions sur la taille corporelle des populations de rennes. Les séries analysées dans le cadre de ce travail proviennent tant du registre actuel que fossile. Plusieurs échantillons de populations actuelles (Norvège, Finlande, Groenland) ont ainsi été analysés, afin de tester notre méthodologie et d’envisager des comparaisons morphologiques avec les populations passées. Le corpus paléolithique comporte 29 assemblages naturels et anthropiques du Sud-Ouest de la France, datés majoritairement du dernier Pléniglaciaire et du Tardiglaciaire. La méthode du Variability Size Index appliquée récemment sur le Renne paléolithique posant des problèmes, s’agissant notamment de la détermination du sex-ratio d’un assemblage, du caractère significatif ou non des différences morphologiques -isométriques et allométriques - observées..., nous avons eu recours à une nouvelle méthodologie combinant plusieurs outils statistiques appliqués à un nouvel indice de taille (VSI* : Variability Size Index modifié). Les analyses ostéométriques et statistiques que nous avons effectuées tendent à identifier des fluctuations morphologiques temporelles attestant d’adaptations de l’espèce. D’un point de vue synchronique, nos résultats permettent de rejeter l’hypothèse précédemment soutenue de différences entre les rennes tardiglaciaires des Landes d’une part et du secteur Dordogne/Gironde d’autre part. Les données saisonnières tendent toutefois à indiquer une absence de migrations de grande ampleur des rennes selon cet axe Nord/Sud. L’existence de populations distinctes est toutefois proposée entre les rennes des Landes et ceux du Bassin de l’Aude. Le Sud-Ouest de la France, à la fin du Paléolithique supérieur, aurait été occupé de manière pérenne par des troupeaux de rennes, dont le comportement migratoire reste cependant à déterminer plus précisément. / This doctoral research aims at characterizing morphological fluctuations resulting from climate change in palaeolithic reindeers from Southwest France. Indeed, the Last Pleniglacial and the Last Glacial (between 21 500 - 13 000 cal. BP) constituted periods of particularly strong palaeoclimatic and palaeoenvironmental constraints, which ended, either directly or indirectly, in repercussions on the body size of reindeer populations. The series analyzed within the framework of this work result from both current and fossil registers. Several samples of current populations (Norway, Finland, and Greenland) were thus analyzed, in order to experiment our methodology and envisage morphological comparisons with the past populations. The palaeolithic corpus is composed of 29 natural and anthropological assemblages of Southwest France, dated mainly from the Last Pleniglacial and the Last Glacial. Since the Variability Size Index method recently applied to palaeolithic Reindeer raises issues, particularly relating to the determination of an assemblage’s sex-ratio, to the characterization or not of observed morphological differences –either isometric and allometric–, we decided to use a new methodology combining several statistical tools applied to a new size index (VSI*: modified Variability Size Index). Osteometric and statistical analyses that we performed tend to identify temporal morphological fluctuations, demonstrating adaptations of the specie. From a synchronic standpoint, our results allow to reject the hypothesis previously asserted regarding differences between Last Glacial reindeers from Landes on the one hand and the Dordogne/Gironde sector, on the other hand. Seasonal data however tend to indicate an absence of large-scale migrations of reindeers according to such a North/South axis. Nonetheless, the existence of different populations between reindeers of Landes and those of the Aude basin is proposed. Hence, Southwest France, at the end of the upper Palaeolithic, would have been occupied continuously by reindeer herds, the migratory behaviour of which however remains to determine more exactly.