Understanding variation in key functional traits across gradients in high diversity systems and the ecology of community changes along gradients in these systems is crucial in light of conservation and climate change. We examined inter- and intraspecific variation in leaf mass per area (LMA) of sun and shade leaves along a 3330-m elevation gradient in Peru, and in sun leaves across a forest-savanna vegetation gradient in Brazil. We also compared LMA variance ratios (T-statistics metrics) to null models to explore internal (i.e., abiotic) and environmental filtering on community structure along the gradients. Community- weighted LMA increased with decreasing forest cover in Brazil, likely due to increased light availability and water stress, and increased with elevation in Peru, consistent with the leaf economic spectrum strategy expected in colder, less productive environments. A very high species turnover was observed along both environmental gradients, and consequently, the first source of variation in LMA was species turnover. Variation in LMA at the genus or family levels was greater in Peru than in Brazil. Using dominant trees to examine possible filters on community assembly, we found that in Brazil, internal filtering was strongest in the forest, while environmental filtering was observed in the dry savanna. In Peru, internal filtering was observed along 80% of the gradient, perhaps due to variation in taxa or interspecific competition. Environmental filtering was observed at cloud zone edges and in lowlands, possibly due to water and nutrient availability, respectively. These results related to variation in LMA indicate that biodiversity in species rich tropical assemblages may be structured by differential niche-based processes. In the future, specific mechanisms generating these patterns of variation in leaf functional traits across tropical environmental gradients should be explored.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Crustaceans of the genus Aegla occur in continental waters, in southern South America. The genus is composed by more than 70 species, most of them characterized by having restricted distributions. Unlike this pattern, the species Aegla longirostri and Aegla platensis have wide geographic distributions. Moreover, both species form non-monophyletic groups, which may indicate that these groups are formed by cryptic species. Therefore, the objective of this study was to analyze populations of A. longirostri and A. platensis through a geometric morphometric approach, in order to clarify their intraspecific relationships. For A. longirostri, we analyzed 120 individuals from 6 populations, totalizing 20 animals per population. For A. platensis, we analyzed 110 individuals from 11 populations (four Argentinean and seven Brazilian), totalizing 10 animals per population. For both species, the animals were photographed in dorsal view, and 19 landmarks were defined on the carapace. Both sides of the carapace were symmetrized, and the landmarks coordinates were superimposed. Variations in centroid size were tested with an analysis of variance (ANOVA) and Tukey s test. For A. longirostri, we also used a Procrustes ANOVA. Variations in carapace shape were explored through a principal component analysis (PCA), and afterwards through a linear discriminant analysis (LDA) and a canonical variate analysis (CVA), based on the first 8 principal components. The Mahalanobis distances between the populations were calculated. For statistical test of carapace shape differences, we used multivariate analysis of variance (MANOVA), and for pairwise comparisons among populations we used Bonferroni corrections for adjust of p-value after multiple MANOVAs. For A. longirostri, CV1 and CV2 represented 46.5% and 23.1% of the variation, respectively. The most geographically distant population showed the highest values of Mahalanobis distance. The pairwise comparisons showed that all populations of A. longirostri differ significantly in carapace shape. For A. platensis, CV1 and CV2 represented 28.5% and 22.2% of the variation, respectively. There was a separation between Argentinean and Brazilian populations, with high values of Mahalanobis distances between populations from both countries. The pairwise comparisons showed that all populations of A. platensis differ significantly in carapace shape, with the exception of a pair of Argentinean populations and a pair of Brazilian populations. Some characteristics of the aeglids indicate that these animals may have low dispersal potential, thus the geographic distance may have led to an interruption of the gene flow between populations. Added to the non-monophyletic grouping, the intraspecific difference in carapace shape in A. longirostri and A. platensis could be an evidence that populations of both species are fragmented. / Crustáceos do gênero Aegla ocorrem em águas continentais, no sul da América do Sul. O gênero é composto por mais de 70 espécies, caracterizadas em sua maioria por possuírem distribuições restritas. Ao contrário deste padrão, as espécies Aegla longirostri e Aegla platensis possuem distribuições geográficas amplas. Além disso, ambas as espécies formam agrupamentos não-monofiléticos, o que pode indicar que esses agrupamentos são formados por espécies crípticas. Portanto, o objetivo deste estudo foi analisar populações de A. longirostri e A. platensis através de técnicas de morfometria geométrica, visando esclarecer suas relações intraespecíficas. Para A. longirostri, foram analisados 120 indivíduos provenientes de seis populações, totalizando 20 animais de cada população. Para A. platensis, foram analisados 110 indivíduos provenientes de 11 populações (quatro argentinas e sete brasileiras), totalizando 10 animais de cada população. Para ambas as espécies, os animais foram fotografados em vista dorsal e foram selecionados 19 marcos anatômicos localizados na carapaça. Ambos os lados da carapaça foram simetrizados e as coordenadas dos marcos anatômicos foram sobrepostas. Variações no tamanho do centroide foram testadas através de análise de variância (ANOVA) de um critério e teste de Tukey. Para A. longirostri, também foi utilizada ANOVA de Procrustes. Variações na forma da carapaça foram exploradas através de análise de componentes principais (PCA), e posteriormente através de análise linear discriminante (LDA) e análise de variáveis canônicas (CVA), com base nos 8 primeiros componentes principais. Foi calculada a distância de Mahalanobis entre as populações. Variações na forma da carapaça foram testadas através de análise de variância multivariada (MANOVA) e MANOVAs par a par seguidas por correção de Bonferroni. Para A. longirostri, CV1 e CV2 corresponderam a 46,5% e 23,1% da variação, respectivamente. A população mais distante geograficamente apresentou os maiores valores de distância de Mahalanobis. As MANOVAs par a par demonstraram que todas as populações de A. longirostri diferem significativamente na forma da carapaça. Para A. platensis, CV1 e CV2 corresponderam a 28,5% e 22,2% da variação, respectivamente. Houve uma separação entre as populações argentinas e brasileiras, com valores de distância de Mahalanobis maiores entre as populações dos dois países. As MANOVAs par a par demonstraram que todas as populações de A. platensis diferem significativamente na forma da carapaça, com exceção de um par de populações argentinas e um par de populações brasileiras. Algumas características dos eglídeos indicam que esses animais possuem baixo potencial de dispersão, portanto, a distância geográfica pode ter levado à interrupção do fluxo gênico entre as populações. Somada à ausência de monofilia, a diferença intraespecífica na forma da carapaça em A. longirostri e A. platensis pode ser um indício de que populações de ambas as espécies estão fragmentadas.

Two peccary species, Mylohyus elmorei and Prosthennops serus are described from the medium-bodied fauna of the Gray Fossil Site (GFS) of northeastern Tennessee. This site, recognized as an oak-hickory forest, is latest Hemphillian or earliest Blancan based on mammalian biochronology, with an estimated age of 4.9-4.5 Ma. The GFS represents the only site outside the Palmetto Fauna of Florida with M. elmorei, greatly expanding the species range north over 920 km, well into the Appalachian region. This is also the first Appalachian occurrence of the relatively widespread P. serus. Our understanding of intraspecific variation for both M. elmorei and P. serus is expanded due to morphological and proportional differences found in cranial and dental material from the GFS, Tyner Farm locality, Palmetto Fauna, and within the literature. The GFS M. elmorei material represents the most complete mandible and second cranium for the species, and preserve intraspecific variation in the length of the diastema, dental proportions, and the complexity of the cuspules of the hypoconulid complex. Similarly, mandibular material from the GFS for P. serus exhibited larger dentitions and a greater degree of robustness than currently recognized for the species.

Os extratos de média polaridade de sete indivíduos de Piper solmsianum coletados em diferentes localidades foram analisados por cromatografia líquida de alta eficiência para se verificar diferenças quantitativas na concentração relativa de apiol, dilapiol, miristicina, grandisina, elemicina, isoelemicina e lignana tetraidrofurânica rel- (7R, 8R, 7\'R, 8\'R)-3,4,3\',4\'-dimetilenodioxi-5,5\'-dimetoxi-7,7\'-epoxilignana. Todos os perfis cromatográficos consistiam de apenas dois, três ou quatro picos majoritários. O(s) composto(s) majoritário(s) era(m) distinto(s) de planta para planta, e em um dos espécimes o pico predominante não era nenhum dos sete metabólitos secundários avaliados. Estudaram-se as variações diárias e anuais em três espécimes de uma população selvagem de P. solmsianum localizada na Reserva da CUASO, em São Paulo. A grandisina apresentou teores máximos no início da noite e teores mínimos no início da manhã. Apiol/dilapiol apresentou variação circadianas evidentes apenas em dois indivíduos, sendo que em um deles o teor máximo ocorreu por volta das oito horas da noite, e no outro, o teor máximo ocorreu por volta das cinco horas da manhã. A variação sazonal mostrou pequena amplitude de oscilação. Em dois espécimes o máximo teor de apiol/dilapiol e grandisina ocorreu no verão. No terceiro espécime não se observou variação periódica anual. / The crude extracts of seven individuals of Piper solmsianum collected in different places were analyzed by high efficiency liquid chromatography (HPLC) in order to determine changes in the relative content of apiol, dillapiol, myristicin, grandisin, elemicin, isoelemicin, and tetrahydrofuran lignan rel-(7R,8R,7R,8R)-3,4,3,4- dimethylenedioxy-5,5-dimethoxy-7,7-epoxylignan. All chromatographic profiles consisted of two, three or four major peaks with significant qualitative and quantitative differences. Major components were different from plant to plant and in one specimen an component different from the seven metabolites observed in most cases. The leaf extracts from three wild specimens of P. solmsianum collected at CUASO Reserve, showed annual and diurnal variations in apiol/dillapiol and grandisin relative concentrations. Three plants presented circadian variation with maximum content of grandisin late afternoon, and minimum content in the dawn. Apiol/dillapiol displayed clear circadian variation in two individuals, but without synchrony between phases. The maximum content was observed and in a second specimen around 8 p.m., and in the another specimen, the maximum content occur was observed at 5 a.m. The seasonal variation showed small amplitude of oscillation and in two individuals the maxima contents of apiol/dillapiol and grandisin were observed in summer

Plants are threatened by global change, increasing variability in weather patterns, and associated abiotic stress. Consequently, there is an urgent need to enhance our ability to predict plant community dynamics, shifts in species distributions, and physiological responses to environmental challenges. By building a fundamental understanding of plant stress tolerance, it may be possibly to protect the ecological services, economic industries, and communities that depend on plants. Dehydration tolerance (DhT) is an important mechanism of water stress tolerance with promising translational applications. Here, I take advantage natural variation in DhT to gain a deeper insight into this complex trait. In addition, I address questions related to the causes and consequences of sexual dimorphisms in DhT. Understanding sexual dimorphisms in stress tolerance is critical because these dimorphisms can drive spatial segregation of the sexes, biased sex ratios, and may ultimately reduce sexual reproduction and population persistence. This work takes an integrated approach, addressing DhT on multiple scales from ecology, to physiology, to genomics in the tropical liverwort Marchantia inflexa. Initially, I tested for correlations between DhT and environmental dryness, sex differences in DhT, and genetic vs. plastic contributions to DhT variability. I found that patterns of variation in DhT are associated with environmental variability, including complex sexual dimorphisms, and derive from a combination of plasticity and genetic differences in DhT. Subsequently, I leveraged the variability in DhT to identify candidate DhT enhancing genes. In M. inflexa intraspecific differences in DhT are impacted by baseline variability among plants, as well as unique gene expression responses initiated during drying. In parallel, I assembled a draft genome assembly for M. inflexa, which was employed to investigate questions of sex chromosome evolution and sexual dimorphism in DhT. Finally, the bacteriome of M. inflexa was characterized and found to be extremely diverse and variable. Collectively, this work adds to a growing understanding of DhT and highlights the importance of sampling approaches that seek to comprehensively describe variability in DhT. I detected complex patterns of variability in DhT among populations and the sexes of M. inflexa, which were used to gain insight into the genetic intricacies of DhT.

The study of speciation is key to understanding the origins of biodiversity. Model organisms, with a host of genetic and molecular tools, are crucial to dissecting the genetics of speciation. Crosses between the recently-discovered Caenorhabditis sp. 9 and the well-known C. briggsae produce fertile F1 hybrid females, opening the door to genetic studies of speciation for the first time within the genus. I crossed eight different isogenic strains of C. briggsae reciprocally with six inbred lines of C. sp. 9 to investigate: Haldane’s rule, systematic asymmetries in hybrid viability, and whether genetic variation for hybrid viability segregates within each species. Results of these crosses confirm Haldane’s rule and demonstrate strong asymmetric parent-of-origin effects. Furthermore, I observed genotype-dependent differences in the number of F1 hybrid progeny. This provides evidence for genetic variation for hybrid viability within both species, allowing insights into the genetic forces driving the evolution of incompatibility loci.

The study of speciation is key to understanding the origins of biodiversity. Model organisms, with a host of genetic and molecular tools, are crucial to dissecting the genetics of speciation. Crosses between the recently-discovered Caenorhabditis sp. 9 and the well-known C. briggsae produce fertile F1 hybrid females, opening the door to genetic studies of speciation for the first time within the genus. I crossed eight different isogenic strains of C. briggsae reciprocally with six inbred lines of C. sp. 9 to investigate: Haldane’s rule, systematic asymmetries in hybrid viability, and whether genetic variation for hybrid viability segregates within each species. Results of these crosses confirm Haldane’s rule and demonstrate strong asymmetric parent-of-origin effects. Furthermore, I observed genotype-dependent differences in the number of F1 hybrid progeny. This provides evidence for genetic variation for hybrid viability within both species, allowing insights into the genetic forces driving the evolution of incompatibility loci.

Made available in DSpace on 2016-12-23T13:47:35Z (GMT). No. of bitstreams: 1 Dissertacao de Simone Loss de Freitas.pdf: 2778831 bytes, checksum: f273846469d08eec6a2e5aafffe5602f (MD5) Previous issue date: 2007-03-27 / A catita Gracilinanus microtarsus ocorre principalmente ao longo da Mata Atlântica do leste e sul do Brasil. Estudos prévios relevaram altos níveis de divergência genética entre amostras ao longo de sua distribuição. Nesse trabalho nós analisamos a congruência da variação geográfica entre caracteres moleculares e morfológicos para avaliar se populações identificadas como Gracilinanus microtarsus representam mais de uma espécie, como sugerido anteriormente. Nós examinamos 195 espécimes de G. microtarsus, 94 de G. agilis e 12 de Cryptonanus sp., e inferimos a filogenia com base em 25 caracteres morfológicos discretos. Nós comparamos os resultados com uma filogenia baseada em seqüências parciais de citocromo b de 27 espécimes. A monofilia do gênero e das duas espécies G. microtarsus e G. agilis foram corroboradas pelas análises de dados morfológicos e moleculares. A filogenia molecular mostrou três clados e a filogenia com base em dados morfológicos apresentou três linhagens em G. microtarsus, as quais também se segregaram no espaço morfométrico, indicando a possibilidade de existirem três espécies em G. microtarsus. No entanto, as filogenias morfológicas e moleculares não se apresentaram completamente congruentes ao serem comparadas e a análise morfológica resultou como parafilética na filogenia molecular. Portanto, nossos resultados sugerem que G. microtarsus representa apenas uma espécie, diagnosticável por caracteres morfológicos e moleculares, mostrando forte variação morfológica ao longo de sua distribuição / The gracile mouse opossum Gracilinanus microtarsus occurs mainly along the Atlantic forest of eastern and southern Brazil. Earlier studies revealed high levels of genetic divergence among samples across its range. Here, we analyzed the congruence of geographic variation between molecular and morphological characters to evaluate whether the populations that have been segregated by molecular divergence represent more than one species, as previously suggested. We examined 195 specimens of G. microtarsus, 94 of G. agilis, and 12 of Cryptonanus sp., and inferred a phylogeny based on 25 discrete morphological characters. We compared this result with a phylogeny based on partial cytochrome b sequences of 27 specimens. The monophyly of the genus, and of both G. microtarsus and G. agilis were corroborated by morphological and molecular analyses. The molecular phylogeny recovered three clades, and the morphological data indicated three distinct lineages, which also segregated in morphometric space, indicating the possibility of occurrence of three cryptic species within what is currently identified as G. microtarsus. However, morphological and molecular phylogenies were not completely congruent, and the morphological classification of the specimens included in the molecular analysis resulted in a paraphyletic group in the molecular phylogeny. Hence, our results suggest that G. microtarsus represents one species, diagnosable by morphological and molecular characters, showing strong morphological and molecular variation throughout its distributional range

Os extratos de média polaridade de sete indivíduos de Piper solmsianum coletados em diferentes localidades foram analisados por cromatografia líquida de alta eficiência para se verificar diferenças quantitativas na concentração relativa de apiol, dilapiol, miristicina, grandisina, elemicina, isoelemicina e lignana tetraidrofurânica rel- (7R, 8R, 7\'R, 8\'R)-3,4,3\',4\'-dimetilenodioxi-5,5\'-dimetoxi-7,7\'-epoxilignana. Todos os perfis cromatográficos consistiam de apenas dois, três ou quatro picos majoritários. O(s) composto(s) majoritário(s) era(m) distinto(s) de planta para planta, e em um dos espécimes o pico predominante não era nenhum dos sete metabólitos secundários avaliados. Estudaram-se as variações diárias e anuais em três espécimes de uma população selvagem de P. solmsianum localizada na Reserva da CUASO, em São Paulo. A grandisina apresentou teores máximos no início da noite e teores mínimos no início da manhã. Apiol/dilapiol apresentou variação circadianas evidentes apenas em dois indivíduos, sendo que em um deles o teor máximo ocorreu por volta das oito horas da noite, e no outro, o teor máximo ocorreu por volta das cinco horas da manhã. A variação sazonal mostrou pequena amplitude de oscilação. Em dois espécimes o máximo teor de apiol/dilapiol e grandisina ocorreu no verão. No terceiro espécime não se observou variação periódica anual. / The crude extracts of seven individuals of Piper solmsianum collected in different places were analyzed by high efficiency liquid chromatography (HPLC) in order to determine changes in the relative content of apiol, dillapiol, myristicin, grandisin, elemicin, isoelemicin, and tetrahydrofuran lignan rel-(7R,8R,7R,8R)-3,4,3,4- dimethylenedioxy-5,5-dimethoxy-7,7-epoxylignan. All chromatographic profiles consisted of two, three or four major peaks with significant qualitative and quantitative differences. Major components were different from plant to plant and in one specimen an component different from the seven metabolites observed in most cases. The leaf extracts from three wild specimens of P. solmsianum collected at CUASO Reserve, showed annual and diurnal variations in apiol/dillapiol and grandisin relative concentrations. Three plants presented circadian variation with maximum content of grandisin late afternoon, and minimum content in the dawn. Apiol/dillapiol displayed clear circadian variation in two individuals, but without synchrony between phases. The maximum content was observed and in a second specimen around 8 p.m., and in the another specimen, the maximum content occur was observed at 5 a.m. The seasonal variation showed small amplitude of oscillation and in two individuals the maxima contents of apiol/dillapiol and grandisin were observed in summer

Les sols enrichis en éléments traces métalliques, encore appelés sols métallifères, constituent un modèle original pour l’étude des processus écologiques et évolutifs opérant au sein de la végétation qui y est associée. Au Sud-Est de l’Afrique centrale, dans l’ex-province du Katanga, une succession d’affleurements naturels de roches enrichies en cuivre (Cu) et en cobalt (Co), uniques en leur genre à la surface de la terre, forment le très célèbre « Arc Cuprifère Katangais ». De véritables « collines de cuivre », isolées géographiquement dans une matrice de forêt claire, s’étendent sur plus de 300 Km et constituent des écosystèmes remarquables attirant l’attention de chercheurs depuis plus d’un demi-siècle.Les conditions écologiques extrêmes des collines de Cu et de Co, liées principalement à des concentrations métalliques élevées dans les sols (1 000 à 10 000 fois supérieures aux sols normaux), ont sélectionné des végétations hautement originales et uniques composées de métallophytes, aussi appelées cupro-cobaltophytes, pouvant toutefois présenter des niches écologiques très variables. Certaines de ces plantes possèdent même la fascinante particularité d’accumuler le Cu et/ou le Co dans leurs tissus foliaires à des niveaux de concentrations extrêmement toxiques pour des plantes normales, et sont qualifiées arbitrairement d’hyperaccumulatrices. À ce jour, de fortes variations d’accumulation du Cu et du Co encore mal comprises sont observées chez ces cupro-cobaltophytes. Celles-ci pourraient être expliquées par une variation de la disponibilité du Cu et du Co dans les sols, par une variabilité des mécanismes de tolérance au Cu et au Co, et par une variation de la capacité à accumuler ces métaux.Certaines cupro-cobaltophytes sont restreintes de ces habitats métallifères hors-normes, et d’autres se distribuent plus largement, possédant également des populations au sein d’habitats non-métallifères, en savane ou en forêt, sur sol normal. Ces dernières, à plus large distribution écologique, sont qualifiées de cupro-cobaltophytes facultatives, et constituent des modèles biologiques hautement intéressants pour étudier les processus écologiques et évolutifs liés à la tolérance et l’accumulation du Cu et du Co.La biogéochimie, l’écologie et l’évolution de la tolérance et de l’accumulation du Cu et du Co chez les cupro-cobaltophytes facultatives restent à ce jour peu connues, surtout pour le Co. La stratégie de recherche repose sur une approche interdisciplinaire (biogéochimie, écologie fonctionnelle et écologie évolutive) qui s’articule autour de travaux réalisés à la fois sur le terrain et en conditions contrôlées :sur un sol et en hydroponie. Chez une métallophyte facultative modèle à large amplitude écogéographique :Anisopappus chinensis (Asteraceae), la thèse s’attache à :(i) caractériser la variation phénotypique de l’accumulation du Cu et du Co et connaître les facteurs édaphiques qui l’influence, pour mieux comprendre la disponibilité du Cu et du Co dans les sols métallifères, (ii) tester l’influence de facteurs chimiques du sol sur la mobilité du Cu et du Co dans les sols et sur l’accumulation foliaire de Cu et de Co, (iii) étudier la réponse adaptative de populations métallicoles et non-métallicoles provenant d’habitats très contrastés, et leur réponse plastique au Co, (iv) examiner la variabilité génétique de la capacité à tolérer et à accumuler le Cu et le Co entre des populations métallicoles et non-métallicoles.Les variations d’accumulation de Cu et de Co observées au sein des populations métallicoles d’A. chinensis seraient en grande partie influencées par la teneur en matière organique et les concentrations totales en manganèse et en fer des sols de la zone racinaire. Le Cu et le Co potentiellement dans la solution du sol ne sembleraient pas être les seules fractions expliquant les variations d’accumulation. Les concentrations de Cu et de Co liées respectivement aux oxydes de manganèse et à la matière organique pourraient également représenter une concentration significativement disponible pour les plantes. En culture, une variation dans la mobilité du Cu et du Co dans le sol n’expliquait pas nécessairement une variation dans les concentrations foliaires mesurées chez A. chinensis. La disponibilité du Cu et du Co en milieu métallifère est un concept difficile à appréhender, élément- et espèce-dépendant, qui serait la résultante d’interactions biogéochimiques complexes à l’échelle de la rhizosphère, impliquant les microorganismes.Il existe une réponse adaptative à la diversité d’habitats chez A. chinensis traduite par des hauteurs de plantes et surfaces de feuilles plus faibles chez les populations métallicoles étudiées. Malgré des sols très contrastés chimiquement entre habitats métallifères et non-métallifères, très peu de variations intraspécifiques de la surface foliaire spécifique et des concentrations foliaires en nutriments ont été observées. La très faible réponse plastique au Co chez les populations étudiées d’A. chinensis semble mettre en évidence une homéostasiedes traits fonctionnels foliaires mesurés, qui pourrait expliquer la large niche écologique de l’espèce.La tolérance au Cu n’est pas un attribut vérifié à l’échelle de l’espèce chez A. chinensis. Celle-ci semblerait s’exprimer dans des conditions édaphiques bien particulières sur les sols métallifères, et pourrait être le fruit de processus rhizosphériques impliquant les microorganismes. Une différenciation génétique de la tolérance au Co a été observée chez les populations métallicoles des sols enrichis en Co. Une relation positive entre le degré de tolérance au Co et le niveau de concentration en Co dans le sol natif existerait. Pour la première fois chez une métallophyte, une variation génétique de l’accumulation de Co a été mise en évidence. L’hyperaccumulation du Cu et du Co chez les métallophytes, à de faibles concentrations disponibles dans les sols, n’existerait pas. Anisopappus chinensis provenant de sols enrichis en Co constitue un matériel végétal remarquable à valoriser, puisque s’exprimant comme une véritable accumulatrice de Co en conditions contrôlées. / Soils enriched in trace metal elements (TE) (i.e. metalliferous soils) constitute original model systems to study ecological and evolutionary processes occurring among their associated vegetation. In Southeastern central Africa (Katanga), a unique succession of natural copper (Cu) and cobalt (Co) outcrops occurs; the so-called “Katangan Copperbelt”. Here, scattered over 300 Km, geographically isolated “copper hills” form remarkable ecosystems that strongly contrast with the surrounding clear forest.Soil Cu and Co concentrations of those hills can be 1000- to 10 000-fold higher than in normal soils. These extreme ecological conditions have selected a unique vegetation of metallophytes, also called cupro-cobaltophytes. Some plants have the fascinating peculiarity to accumulate Cu and Co in their tissues up to extremely phytotoxic concentrations and are called “hyperaccumulators”. High misunderstood inter and intraspecific variations of Cu and Co accumulation are observed within this flora. These variations could be explained by variations in Cu and Co availability in soils, but also by inter and intraspecific variations in Cu and Co tolerance mechanisms and capacity to accumulate Cu and Co.Some cupro-cobaltophytes are restricted to metalliferous habitats (i.e. endemic metallophytes) and some are widely distributed, with populations on normal soils (i.e. facultative metallophytes). These latter are of high interest to study the ecology and evolution of Cu and Co tolerance and accumulation.Biogeochemistry, ecology and evolution of Cu and Co tolerance and accumulation in facultative cupro-cobaltophytes remains poorly understood, especially for Co. Research strategy was to develop a transdisciplinary approach (biogeochemistry, functional ecology and evolutionary ecology) based on field works and experiments (using soil or nutrient solution). For Anisopappus chinensis (Asteraceae), a broad-niched and geographically widespread facultative metallophyte chosen as model species, this PhD thesis aims at: (i) investigate the phenotypic variation of Cu and Co accumulation, and the influencing soil chemical factors, to understand better Cu and Co availability in metalliferous soils, (ii) test the influence of soil chemical factors on Cu and Co mobility in soil and accumulation, (iii) studyadaptive response of metallicolous (M) and non-metallicolous (NM) populations from contrasted habitats, and their plastic response to Co, (iv) examine the genetic variation in Cu and Co tolerance and accumulation between M and NM populations.Copper and Co accumulation variations among M populations of A. chinensis are clearly influenced by organic matter content and soil total manganese and iron concentrations in the rooting zone. Mobile Cu and Co concentrations, potentially in the soil solution, would not only explain Cu and Co accumulation variations. Copper and Co bound to respectively manganese oxides and organic matter could also represent Cu and Co available concentrations for plants. In experimental conditions, variations in Cu and Co mobility would not necessary explained variations in foliar Cu and Co concentrations in A. chinensis. Copper and Co availability is a complex element- and species-specific mechanism, closely related to all biogeochemical processes that occur in the rhizosphere. Important role of microorganisms is expected.Adaptive response to habitats has been highlighted for A. chinensis. Metallicolous plants had consistently lower height and leaf size than NM plants. Despite strong contrast in the soil chemistry between metalliferous and non-metalliferous habitats, very few variations in specific leaf area and leaf nutrient concentrations was observed between M and NM populations. The low plastic response to Co seems to reveal homeostasis of the studied functional leaf traits, which might explain the broad ecological niche of the species.Tolerance to Cu is not constitutive of A. chinensis and would be express under specific growth conditions in nature. Expression of Cu tolerance could be the result of specific soil-plant-microorganisms processes. Genetic differentiation in Co tolerance has been demonstrated in M populations from Co-enriched soils. Positive relationship between the level of tolerance to Co and the concentration of Co in the native soil may exist. Genetic variability of Co accumulation has been demonstrated for the first time in a metallophyte. Cu and Co hyperaccumulation at low available concentration in the soil would not exist in metallophytes. Anisopappus chinensis form Co-enriched soils expressed as a genuine Co accumulator and thus, constitute an interesting valuable biological model. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished