The genus Picea is located from temperate to Taiga (boreal) regions of northern hemisphere from subtropical to high altitude with 34 species. Picea orientalis is endemic to Eastern Black Sea Mountainous region of Turkey and Western Caucasus. To determine the genetic relatedness within Picea orientalis populations, as well as the relationship between other Pinaceae species from database, populations were sampled from 15 different locations within the natural range of species and grouped into 5 depending on several criteria. In order to evaluate the genetic structure of the taxon, non-coding trn and matK regions of choloroplast DNA (cpDNA) were sequenced. According to genetic diversity analysis of 15 Picea orientalis populations with respect to trn and matK regions, there is not much variation among populations. Among 3 non-coding trn and the matK region, there is only one variable site which was parsimony informative. The results indicated that the populations from Artvin had the highest divergence. In this study, the genetic divergence of Picea orientalis from other Pinaceae species were also observed. According to the results obtained from trnV region the studied Picea orientalis observed to display a close relationship with Larix and distinct from other Pinaceae especially Pinus genus. This result is unrepresentative due to the results of other studies. Moreover, as a result of analysis with trncd-ef region, the studied Picea orientalis populations possessed close relationship with species from clade Picea. Moreover, based on molecular clock estimations the studied Picea orientalis populations had close relationships with the species form Asia. Finally, the relationship of Picea orientalis with other Picea species were analyzed with respect to matK region. The result is consistent with the results of trncd-ef region and also with other studies.

The genus Chrysopsis (Asteraceae) contains eleven species native to Florida, including the newly described species, Chrysopsis delaneyi. Populations of this endemic plant species inhabit the Lake Wales Ridge (LWR) and the Atlantic Ridge (AR) of the Florida peninsula. Differences in morphology have been demonstrated within C. delaneyi, based on their locations. My objective was to determine the relationships between the LWR and the AR populations by analysis of chloroplast sequence and nuclear sequence variation. Approximately 160 samples of C. delaneyi and its sister species C. scabrella have been collected from fifteen sites throughout Florida. Six single base differences were detected, one insertion, and one variable short duplication. A total of four haplotypes (i.e.: groups that have different combinations of polymorphisms) have been found. For the most part, one haplotype is found in LWR populations and is indistinguishable from that found in C. scabrella. Another haplotype is found primarily in AR populations and is more similar to haplotypes found in the more distantly related C. highlandsensis and C. floridana. One haplotype is found within populations of C. scabrella. The last haplotype in one AR population contains two polymorphic loci, one site is representative of the AR populations, and the other site is that of the LWR populations. Only one mixed population has been found, at the northern end of the AR range. These results are not consistent with taxonomic relationships inferred from morphological characteristics; hence the results suggest that chloroplast DNA (cpDNA) relationships may be the consequence of one or more instances of chloroplast capture.

Variability in the genetic information DNA tracking individuals carry is easy to detect using molecular markers. In the thesis we examined related Dracaena species. For the study of genetic diversity in the genus Dracaena are used mainly noncoding regions of cpDNA, spacer trnH -- psbA, regions trnL -- trnF and trnS -- trnG -- trnG, which are more variable than coding regions. Also used in this work were coding regions of matK and rbcL. In the genus Dracaena belongs xerophytic species that are characterized by typical shaped treetop. 14 representatives of species were used in thesis growing in tropical regions of the African continent and adjacent islands and the southeastern part of the Arabian peninsula. They are monocotyledonous trees with atypical abilities of secondary thickness of trunk, which I find interesting. The massive trunk is very strong and there is potencial to used it for wood. Trees are very significant for their red plant sap which flowing from demaged trunk. The sap is very precious resource which is used in many areas of industry, for example pharmacy, traditional medicine, dye making etc. Determination of genetic affinity was based on an amplification of cpDNA template of individual Dracaena samples with primers for the studied regions. Data was obtained and evaluated by Multiple alignment program ClustalX and BioEdit after their sequencing. Evalueted data was used to create dendograms affinity. According the resulting phylogenetic tree we find out similarities and identified relationship of the monitored species of the genus Dracaena. The main purpose of research was to get answers to understand phylogenetic relationship between group of Dracaena forestry used trees. The thesis was made in cooperation of Department of Forest Botany, Dendrology and Geobiocoenology, Faculty of Forestry and Wood Technology of Mendel University in Brno.

Eight of fifteen species in genus Anthoxanthum (Poaceae) can be found in Europe. Five of them are perennials forming A. odoratum complex, the remaining three are annual, more or less mediterranean taxa (A. aristatum, A. ovatum and A. gracile). Within the A. odoratum s. l. complex the following taxa are distinguished: widely spread A. odoratum s. str. (4x; 2n = 20), arcto-alpine A. alpinum (2x a 4x; 2n = 10 and 20), Madeiran endemic species A. maderense (2x; 2n = 10), endemic species of Balkan mountains A. pauciflorum (2x; 2n = 10) and the Iberian peninsula endemic A. amarum (?x; 2n ~ 90). The aim of this thesis is to clearify the unknown evolutionary relationships between the taxa, between the annuals and perennials, diploids and polyploids. The following questions should be answered in this study: 1) What is the origin and distribution of the rediscovered diploid perennial taxon and what is its relationship to the other members of the group; 2) What is the distribution pattern of the perennial taxa of the genus Anthoxanthum in Europe and what is their haplotype differenciation (overall distribution of the taxa and haplotypes and the existence of their sympatric occurence); 3) What evolutionary ties exist among the species and what is the origin of allotetraploid taxon A. odoratum s.str. The...

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Made available in DSpace on 2014-07-29T14:52:09Z (GMT). No. of bitstreams: 1 Tese thannya nascimento.pdf: 3166640 bytes, checksum: 0a9faeb659c9594423ee5e7f8b495662 (MD5) Previous issue date: 2009-01-22 / The goal of this study was to evaluate the genetic structure and the spatial pattern of intra and interpopulational gene flow of Dipteryx alata Vogel, based on nuclear and chloroplastidial microsatellite markers. Primers were developed based on sequencing of random fragments from a shotgun genomic library for detection of microsatellite regions. 12 microsatellites regions were obtained from 688 sequences, which allowed the construction of pairs of primers. These regions are composed of motifs with two to six nucleotides, ranging from 136 to 380 base pairs. This shows that the random sequencing strategy from shotgun libraries is interesting because it allows the achievement of primers for repetitive regions with different motifs. Two of these loci (Da_E06 e Da_E12) were polymorphic with three alleles each. He estimation for these loci showed satisfactory values (0.2946 and 0.2879, respectively), considering the number of alleles. Also, we used a transferred primer from the species Phaseolus vulgaris (BM164) for D. alata. Moreover, other two chloroplastidials microsatellite primers were used for molecular analyses of georeferenced subpopulations, totalizing 775 plants distributed over the natural occurrence area of Cerrado. 210 of these plants were collected and georeferenced one by one along the margins of the Araguaia River in the states of Mato-Grosso (RAMT) and Goiás (RAGO) for spatial distribution of genetic variability in local scale analysis. The relationship between estimations of genetic diversity parameters with patterns of potential distribution of species was evaluated. This was used to test the hypothesis that the genetic variability of D. alata populations is distributed according to the central-periphery model. D. alata subpopulations showed considerable high levels of genetic variability that was significantly structured among subpopulations and well structured in space, both for nuclear and chloroplastidial data. The estimation of the apparent cross-fertilization rate (ta = 1.0575) indicates that the species is allogamous. Estimations of migration rates by pollen and by seeds were lower than one, indicating that seed dispersal contributes more effectively for total gene flow. Estimates of the genetic diversity parameters from the Araguaia River population showed similar values between both margins. The estimation of the apparent cross-fertilization rate (0.9434) indicated that the Araguaia River is not a physical barrier to effective gene flow. The effective size of the neighborhood, i.e., the mean number of individuals in an area where panmixia occurs was 85.64 and 22.99 for nuclear and chloroplastidial data, respectively, indicating that seed dispersal is more restricted. The correlogram generated with chloroplastidial data presented a cline pattern of variance more evident than with nuclear data, suggesting that the presence of spatial genetic structure is being more influenced by seed dispersal. We observed that the genetic parameters do not follow a classical central-periphery model, because peripheral population (according to geographical distribution of sampling locations) tended to demonstrate higher values for these estimations, mainly the South and Western subpopulations. The relationship found between the fixation index (f) with human impact indicated that the subpopulations evaluated can be affected by fragmentation process and land use, probably caused by the recent human colonization in Cerrado biome. / O objetivo geral deste estudo foi avaliar a estrutura genética e o padrão espacial do fluxo gênico intra e interpopulacional de Dipteryx alata Vogel, com base em marcadores microssatélites nucleares e cloroplastidiais. Foi utilizada uma estratégia de desenvolvimento de iniciadores que se baseia no seqüenciamento aleatório de fragmentos provenientes de uma biblioteca genômica shotgun para a detecção de regiões microssatélites, em barueiro. Das 668 sequências obtidas, foram encontradas 12 regiões microssatélites que possibilitaram a construção dos pares de iniciadores. Estas regiões são compostas por motivos com dois a seis nucleotídeos, que variam entre 136 a 380 pb. Isto mostra que a estratégia de sequenciamento aleatório a partir de bibliotecas shotgun é interessante por possibilitar a obtenção de iniciadores para regiões repetitivas com diferentes motivos. Dois destes locos (Da_E06 e Da_E12) foram polimórficos, apresentando três alelos cada. As estimativas de He para estes locos apresentaram valores satisfatórios, considerando o número de alelos, e foram iguais a 0,2946 e 0,2879, respectivamente. Isto indica que os iniciadores desenvolvidos e padronizados com sucesso neste trabalho podem ser utilizados para estudos genético-populacionais. Juntamente com estes dois iniciadores desenvolvidos, foi utilizado outro transferido da espécie Phaseolus vulgaris (BM164) para D. alata, além de outros dois iniciadores microssatélites cloroplastidiais para análises moleculares de 23 subpopulações georeferenciadas, totalizando 775 plantas, distribuídas ao longo da área de ocorrência natural do Cerrado. Destas plantas, 210 foram coletadas e georreferenciadas uma a uma, ao longo das margens do alto rio Araguaia nos estados de Mato-Grosso (RAMT) e Goiás (RAGO), para análises de distribuição espacial da variabilidade genética em escala local. Para testar a hipótese de que a variabilidade genética das subpopulações de D. alata se distribui conforme o modelo central-periférico, foram avaliadas as relações entre as estimativas de parâmetro genético de diversidade com os padrões de distribuição potencial da espécie. Foi observado que as subpopulações de D. alata apresentam consideráveis níveis de variabilidade genética que se encontra significativamente estruturada entre as subpopulações, tanto para os dados nucleares quanto para os cloroplastidiais, apresentando-se também estruturada no espaço. A estimativa da taxa de fecundação cruzada aparente (ta = 1,0575) indica que a espécie seja alógama. As estimativas das razões de migração via pólen e via semente foram menores do que 1, o que indica que a dispersão de sementes contribui mais efetivamente para o fluxo gênico total em escala regional. As estimativas dos parâmetros genéticos de diversidade referentes à população contígua ao Rio Araguaia mostraram valores semelhantes entre as margens do rio. A estimativa da taxa de fecundação cruzada aparente (0,9434) confirma a reprodução por alogamia no barueiro. O baixo nível de diferenciação entre as subpopulações das duas margens do rio indica que o rio Araguaia não confere uma barreira física efetiva ao fluxo gênico. O tamanho efetivo de vizinhança, ou seja, o número médio de indivíduos numa área onde ocorre panmixia, para os dados nucleares e cloroplastidiais foi igual a 85,64 e 22,99, respectivamente, indicando que a dispersão de sementes é mais restrita em escala local. O correlograma gerado a partir dos dados cloroplastidiais apresenta um padrão clinal de variação mais evidente do que o proveniente dos dados nucleares, o que sugere que a presença da estrutura genética espacial deve estar sendo mais influenciada pelo padrão de dispersão da semente. Foi observado que parâmetros genéticos estimados para D. alata não se enquadram no clássico modelo central-periférico, pois as populações tidas como periféricas (de acordo com a distribuição geográfica dos pontos de coleta) tendem a exibir maiores valores para estas estimativas, com destaque para as as subpopulações das bordas Sul e Oeste do bioma. A relação encontrada entre os valores estimados para o índice de fixação intrapopulacional (f) com o impacto humano indica que as subpopulações estudadas podem estar sofrendo as conseqüências dos processos de fragmentação e uso da terra na variabilidade genética, causado provavelmente pelo recente processo de ocupação do Cerrado.

Eurybia et ses proches parents Oreostemma, Herrickia et Triniteurybia sont appelés le grade des eurybioïdes. Comprenant 31 espèces vivaces, ce grade appartient au clade Nord-américain de la tribu des Astereae. Les analyses moléculaires antérieures ont montré que ce groupe est à la fois paraphylétique aux Machaerantherinae et un groupe frère aux Symphyotrichinae. Les relations infragénériques partiellement résolues et faiblement supportées empêchent d’approfondir l'histoire évolutive des groupes et ce, particulièrement dans le genre principal Eurybia. Le but de cette étude est de reconstruire les relations phylogénétiques au sein des eurybioïdes autant par l'inclusion de toutes les espèces du grade que par l’utilisation de différents types de régions et de méthodes d'inférence phylogénétique. Cette étude présente des phylogénies basées sur l'ADN ribosomal nucléaire (ITS, ETS), de l'ADN chloroplastique (trnL-F, trnS-G, trnC-ycf6) et d’un locus du génome nucléaire à faible nombre de copie (CNGC4). Les données sont analysées séparément et combinées à l’aide des approches de parcimonie, bayesienne et de maximum de vraisemblance. Les données ADNnr n’ont pas permis de résoudre les relations entre les espèces polyploïdes des Eurybia. Les analyses combinées avec des loci d’ADNnr et d’ADNnr+cp ont donc été limitées à des diploïdes. Les analyses combinées ont montré une meilleure résolution et un meilleur support que les analyses séparées. La topologie de l’ADNnr+cp était la mieux résolue et supportée. La relation phylogénétique de genres appartenant au grade des eurybioïdes est comme suit : Oreostemma (Herrickia s.str. (Herrickia kingii (Eurybia (Triniteurybia - Machaerantherinae)))). Basé sur la topologie combinée de l’ADNnr+cp, nous avons effectué des analyses de biogéographie à l’aide des logiciels DIVA et LaGrange. Ces analyses ont révélé une première radiation des eurybioïdes dans l’Ouest de l’Amérique du Nord, suivi de deux migrations indépendantes dans l’Est de l’Amérique du Nord chez les Eurybia. Due au relatif manque de variabilité de l’ADNnr, l’ADNcp et CNGC4, où le triage de lignés incomplet était dominant, l'origine du grade est interprétée comme récente, possiblement du Pliocène. La diversification du groupe a été probablement favorisée par les glaciations Pléistocènes. / Eurybia and it relatives, Oreostemma, Herrickia, and Triniteurybia, are collectively called the eurybioid grade. Comprising 31 perennial species, this grade belongs to the North American clade of the tribe Astereae. Early molecular analyses had inferred that this group is paraphyletic to the Machaerantherinae and sister to the Symphyotrichinae. The partially resolved and poorly supported relationships at the infrageneric level within the group, particularly within the core genus Eurybia, is preventing further insights into the evolutionary history of the group. The aim of this study is to reconstruct the phylogenetic relationships among the eurybioids by including all species of the grade and by using both different types of regions and multiple phylogenetic inference methods. The present study provides phylogenies based on nuclear ribosomal DNA (ITS, ETS), chloroplastic DNA (trnL-F, trnS-G, trnC-ycf6), and a low-copy nuclear locus (CNGC4), in separate and combined datasets analyzed using maximum parsimony, Bayesian and maximum likelihood approaches. In a separate analysis of the nrDNA dataset, the relationships of polyploids in Eurybia proved to be impossible to resolve. The nrDNA and nr+cpDNA combined analyses therefore were restricted to diploids. The combined analyses provided greater resolution and support than separate analyses. The nr+cpDNA phylogeny was the best resolved and supported. The phylogenetic relationship of genera belonging to the eurybioid grade is as follows: Oreostemma (Herrickia s.str. (Herrickia kingii (Eurybia (Triniteurybia – Machaerantherinae)))). Based on the nr+ cpDNA combined topology, we performed biogeographical analyses using DIVA and LaGrange. These analyses revealed an initial radiation of the eurybioids in western North America, with two independent migrations to eastern North America within Eurybia. Based on the relative lack of variation in nrDNA, cpDNA and CNGC4, where incomplete lineage sorting was dominant, the origin of the grade is interpreted as recent, probably from the Pliocene. Diversification of the group was probably favored by the Pleistocene glaciations.

Plant domestication is an evolutionary process that leads to several modifications in plants to increase adaptation to cultivation and utilization by humans. These modifications may decrease the fitness of plants in the wild habitat but increase it for human exploitation. Annatto (Bixa orellana L.) is a shrubby plant domesticated in Amazonia from wild annatto (Bixa orellana var. urucurana) populations. This thesis presents a more in-depth understanding of the domestication, mating system and genetic diversity and structure of annatto and its wild ancestor in Brazil. In the first study, a new set of 32 microsatellite loci isolated from a microsatellite-enriched genomic library was developed, of which 12 were polymorphic in populations of both cultivated and wild annatto. In the second study, the genetic diversity and structure of wild annatto populations in Brazilian Amazonia were characterized with 16 microsatellite markers. High population structure and positive correlation between genetic and geographic distances were found, suggesting that genetic differentiation might be caused by geographic isolation. Additionally, Ecological Niche Modeling was used to characterize the potential geographical range of this variety in northern South America and detected that South Rondônia, Madre di Dios River basin, Llanos de Mojos, Llanos de Orinoco and eastern Ecuador are highly suitable areas for wild annatto to occur, providing additional targets for future exploration and conservation. In the third study, 16 microsatellite loci and four phytochemical compounds were used to evaluate the genetic diversity of 63 accessions from the annatto germplasm bank at the Agronomic Institute (IAC). In both molecular and phytochemical analysis the results tended to separate the accessions from Rondônia, northern Brazil, from the Southwestern accessions. Rondônia accessions showed higher values for all the phytochemical compounds and higher levels of genetic diversity. Some accessions presented bixin levels well above the average and are promising materials to be used in genetic improvement programs. In the fourth study, 12 microsatellite loci were used to determine the mating system of a cultivated population of annatto from Rondon do Pará, PA. Multilocus outcrossing rate indicated a mixed mating system for this population. Biparental inbreeding also contributed to the selfing rate in this population. Crossings among related individuals were also observed. Due to this mixed breeding system, the collection of open-pollinated seeds for plant breeding or conservation purposes should include at least 60 plants to ensure a representative sample. In the fifth study, the amount and distribution of genetic diversity among samples of cultivated annatto from homegardens of riverside communities along the major rivers in Brazilian Amazonia, and from farmer´s fields along highways, in the States of Rondônia and Pará, and Southeastern Brazil was characterized. The samples collected presented moderate levels of genetic diversity, and moderate to high levels of admixture between geographic groups, occurring mainly due to exchange of seeds among farmers. However, cluster and Bayesian analyses showed a tendency to group samples based on their geographic origin. Isolation by distance was observed, according to Mantel\'s test. In the last study, wild and cultivated annatto samples from Brazilian Amazonia were compared using 16 microsatellite loci and two cpDNA regions. A clear separation between wild and cultivated annatto, supported by high values of FST in both analyses was observed. Wild samples presented higher rates of diversity in relation to cultivated, partly because these populations did not suffer anthropic selection, as in the cultivated varieties. The data suggest the existence of genetic relationship between wild and cultivated annatto, indicated by moderate levels of gene flow. The results also showed the proximity between groups of cultivated and wild accessions from Rondônia and the Madeira River basin. This proximity provides indications that annatto started its domestication in this area from B. orellana var. urucurana. / Domesticação de plantas é um processo evolutivo que pode gerar uma série de modificações nas plantas para aumentar a adaptação para o cultivo e utilização pelos humanos. Estas modificações podem diminuir a aptidão das plantas no habitat selvagem, porém, aumentando sua aptidão para exploração humana. Urucum (Bixa orellana L.) é uma planta arbustiva domesticada na Amazônia a partir de populações de Bixa orellana var. urucurana. Esta tese apresenta um entendimento mais aprofundado sobre a domesticação, sistema reprodutivo e diversidade genética e estrutura de urucum e seu ancestral selvagem no Brasil. No primeiro estudo, um novo conjunto de 32 locos microssatélites foram isolados a partir de uma biblioteca genômica enriquecida com microssatélites, dos quais 12 foram polimórficos em populações de urucum selvagem e cultivado. No segundo estudo, a diversidade e estrutura genética de populações selvagens de urucum na Amazônia brasileira foram caracterizadas usando 16 marcadores microssatélites. Elevada estrutura populacional, e correlações positivas entre distancias genéticas e geográficas foram observadas, sugerindo que a diferenciação genética é resultante de isolamento geográfico. Adicionalmente, Modelagem de Nicho Ecológico foi utilizada para caracterizar a distribuição potencial desta variedade no norte da América do Sul e observamos que o Sul de Rondônia, a bacia do rio Madre de Dios, os Llanos de Mojos e de Orinoco e oeste do Equador são áreas de alta probabilidade de ocorrência de urucum selvagem, fornecendo informações importantes para novas amostragens e conservação. No terceiro estudo, 16 locos de microssatélites e quatro compostos fitoquímicos foram utilizados para avaliar a diversidade genética de 63 acessos do banco de germoplasma de urucum do Instituto Agronômico (IAC). Em ambas as análises, houve uma tendência de separação dos acessos de Rondônia, norte do Brasil, dos acessos do Sudeste. Os acessos de Rondônia apresentaram elevados valores para todos os compostos fitoquímicos e também apresentaram altos níveis de diversidade genética. Alguns acessos apresentaram níveis de bixina acima da média e são considerados materiais promissores para uso em programas de melhoramento genético de urucum. No quarto estudo, 12 locos microssatélites foram utilizados para determinar o sistema de cruzamento de uma população de urucum de Rondon do Pará, PA. A taxa de cruzamento multilocos indicou um sistema misto de cruzamento para esta população. A endogamia biparental também contribuiu para a taxa de autofecundação. Cruzamentos entre indivíduos aparentados também foram observados. Devido ao sistema misto, a coleta de sementes de polinização aberta para fins de conservação e melhoramento genético deve incluir pelo menos 60 plantas para assegurar uma amostragem representativa. No quinto estudo, a distribuição da diversidade genética entre amostras de urucum cultivado de quintais de comunidades ribeirinhas dos principais rios da Amazônia Brasileira, além de plantações ao longo das rodovias dos estados do Rondônia e Pará, além do Sudeste do Brasil foi caracterizada. As amostras coletadas apresentaram moderados níveis de diversidade genética e moderados a altos níveis de fluxo gênico entre os grupos geográficos, principalmente devido ao intercambio de semente entre agricultores. Contudo, análises Bayesianas e de agrupamento indicaram uma tendência de agrupamento baseado na origem geográfica das amostras. Isolamento por distância também foi observado de acordo com o teste de Mantel. No último estudo, amostras de urucum selvagem e cultivado da Amazônia brasileira foram comparados utilizando 16 locos microssatélites e duas regiões de DNA cloroplastidial. Uma clara separação entre cultivados e selvagens, suportada por altos valores de FST em ambas as análises foi observado. Amostras selvagens apresentaram altas taxas de diversidade em relação aos cultivados, parcialmente por não sofrem seleção antrópica como acontece nas variedades cultivadas. Os dados sugerem a existência de relações genéticas entre urucum selvagem e cultivado, indicado por moderados níveis de fluxo gênico. Os resultados também demonstraram a proximidade entre grupos de urucum selvagem e cultivados de Rondônia e da bacia do Rio Madeira. Esta proximidade fornece indícios que a domesticação de urucum iniciou nesta região a partir de B. orellana var. urucurana.

Evolutionary biology is dependent on accurate phylogenies. In this thesis two branch support methods, Bayesian posterior probablities and bootstrap frequencies, were evaluated with simulated data and empirical data from the chloroplast genome. Bayesian inference was found to be more powerful and less conservative than maximum likelihood bootstrapping, but considerably more sensitive to choice of parameters. Bayesian inference increased in power when data were underparameterized, but the associated increase in type I error was comparatively larger. The chloroplast DNA phylogeny of the tribe Sileneae (Caryophyllaceae) was inferred by analysis of 33,149 aligned nucleotide bases representing 24 taxa. The position of the SW Anatolian taxa Silene cryptoneura and S. sordida strongly disagreed with previous studies on nuclear DNA sequence data, and indicate a possible case of homoploid hybrid origin. Silene atocioides and S. aegyptiaca formed a sister group to Lychnis and remaining Silene, thus suggesting that Silene may be paraphyletic, despite recent revisions based on molecular data. Several nodes in the phylogeny remained poorly supported, despite large amounts of data. Additional sequence sampling is not expected to solve this problem. The main reason for poor resolution is probably a combination of rapid radiation and substitution rate hererogeneity. Apparent incongruent patterns between different regions of the chloroplast genome are evaluated with ancient interspecific chloroplast recombination as explanatory model. Extremely elevated substitution rates in the exons of the plastid clpP gene was documented in Oenothera and three separate lineages of Sileneae. Introns have been lost in some of the lineages, but where present, intron sequences have a markedly slower substitution rate, similar to the rates found in other introns of their genomes. Three branches in the phylogeny show significant whole gene positive selection. In two of the lineages multiple partial copies of the gene were found.

Eurybia et ses proches parents Oreostemma, Herrickia et Triniteurybia sont appelés le grade des eurybioïdes. Comprenant 31 espèces vivaces, ce grade appartient au clade Nord-américain de la tribu des Astereae. Les analyses moléculaires antérieures ont montré que ce groupe est à la fois paraphylétique aux Machaerantherinae et un groupe frère aux Symphyotrichinae. Les relations infragénériques partiellement résolues et faiblement supportées empêchent d’approfondir l'histoire évolutive des groupes et ce, particulièrement dans le genre principal Eurybia. Le but de cette étude est de reconstruire les relations phylogénétiques au sein des eurybioïdes autant par l'inclusion de toutes les espèces du grade que par l’utilisation de différents types de régions et de méthodes d'inférence phylogénétique. Cette étude présente des phylogénies basées sur l'ADN ribosomal nucléaire (ITS, ETS), de l'ADN chloroplastique (trnL-F, trnS-G, trnC-ycf6) et d’un locus du génome nucléaire à faible nombre de copie (CNGC4). Les données sont analysées séparément et combinées à l’aide des approches de parcimonie, bayesienne et de maximum de vraisemblance. Les données ADNnr n’ont pas permis de résoudre les relations entre les espèces polyploïdes des Eurybia. Les analyses combinées avec des loci d’ADNnr et d’ADNnr+cp ont donc été limitées à des diploïdes. Les analyses combinées ont montré une meilleure résolution et un meilleur support que les analyses séparées. La topologie de l’ADNnr+cp était la mieux résolue et supportée. La relation phylogénétique de genres appartenant au grade des eurybioïdes est comme suit : Oreostemma (Herrickia s.str. (Herrickia kingii (Eurybia (Triniteurybia - Machaerantherinae)))). Basé sur la topologie combinée de l’ADNnr+cp, nous avons effectué des analyses de biogéographie à l’aide des logiciels DIVA et LaGrange. Ces analyses ont révélé une première radiation des eurybioïdes dans l’Ouest de l’Amérique du Nord, suivi de deux migrations indépendantes dans l’Est de l’Amérique du Nord chez les Eurybia. Due au relatif manque de variabilité de l’ADNnr, l’ADNcp et CNGC4, où le triage de lignés incomplet était dominant, l'origine du grade est interprétée comme récente, possiblement du Pliocène. La diversification du groupe a été probablement favorisée par les glaciations Pléistocènes. / Eurybia and it relatives, Oreostemma, Herrickia, and Triniteurybia, are collectively called the eurybioid grade. Comprising 31 perennial species, this grade belongs to the North American clade of the tribe Astereae. Early molecular analyses had inferred that this group is paraphyletic to the Machaerantherinae and sister to the Symphyotrichinae. The partially resolved and poorly supported relationships at the infrageneric level within the group, particularly within the core genus Eurybia, is preventing further insights into the evolutionary history of the group. The aim of this study is to reconstruct the phylogenetic relationships among the eurybioids by including all species of the grade and by using both different types of regions and multiple phylogenetic inference methods. The present study provides phylogenies based on nuclear ribosomal DNA (ITS, ETS), chloroplastic DNA (trnL-F, trnS-G, trnC-ycf6), and a low-copy nuclear locus (CNGC4), in separate and combined datasets analyzed using maximum parsimony, Bayesian and maximum likelihood approaches. In a separate analysis of the nrDNA dataset, the relationships of polyploids in Eurybia proved to be impossible to resolve. The nrDNA and nr+cpDNA combined analyses therefore were restricted to diploids. The combined analyses provided greater resolution and support than separate analyses. The nr+cpDNA phylogeny was the best resolved and supported. The phylogenetic relationship of genera belonging to the eurybioid grade is as follows: Oreostemma (Herrickia s.str. (Herrickia kingii (Eurybia (Triniteurybia – Machaerantherinae)))). Based on the nr+ cpDNA combined topology, we performed biogeographical analyses using DIVA and LaGrange. These analyses revealed an initial radiation of the eurybioids in western North America, with two independent migrations to eastern North America within Eurybia. Based on the relative lack of variation in nrDNA, cpDNA and CNGC4, where incomplete lineage sorting was dominant, the origin of the grade is interpreted as recent, probably from the Pliocene. Diversification of the group was probably favored by the Pleistocene glaciations.