Does Speciation between Arabidopsis halleri and Arabidopsis lyrata Coincide with Major Changes in a Molecular Target of Adaptation?

Ever since Darwin proposed natural selection as the driving force for the origin of species, the role of adaptive processes in speciation has remained controversial. In particular, a largely unsolved issue is whether key divergent ecological adaptations are associated with speciation events or evolve secondarily within sister species after the split. The plant Arabidopsis halleri is one of the few species able to colonize soils highly enriched in zinc and cadmium. Recent advances in the molecular genetics of adaptation show that the physiology of this derived ecological trait involves copy number expansions of the AhHMA4 gene, for which orthologs are found in single copy in the closely related A. lyrata and the outgroup A. thaliana. To gain insight into the speciation process, we ask whether adaptive molecular changes at this candidate gene were contemporary with important stages of the speciation process. We first inferred the scenario and timescale of speciation by comparing patterns of variation across the genomic backgrounds of A. halleri and A. lyrata. Then, we estimated the timing of the first duplication of AhHMA4 in A. halleri. Our analysis suggests that the historical split between the two species closely coincides with major changes in this molecular target of adaptation in the A. halleri lineage. These results clearly indicate that these changes evolved in A. halleri well before industrial activities fostered the spread of Zn- and Cd-polluted areas, and suggest that adaptive processes related to heavy-metal homeostasis played a major role in the speciation process

Haute couture et expositions universelles, 1900–1925

À l'Exposition Internationale des Arts Décoratifs de 1925 à Paris, la haute couture est célébrée comme art. Ce n'était pas le cas à l'Exposition universelle de 1900, où elle était industrie. Pendant un quart de siècle, son intégration au sien des Expositions universelles et internationales évolue, suivant sa volonté d'être qualifié d'art, statut qui justifie ses pratiques. Cette article démontre l'importance, pour l'histoire de la mode, de l'étude de la présence de la haute couture aux expositions universelles, dans l'idée de comprendre sa définition de l'époque, en proposant des pistes de recherche et une méthodologie possibles. Dans un premier temps, la position de la haute couture entre art et industrie est discutée, via l'étude des catégories dans lesquelles elle s'insère lors des Expositions universelles, indicatrices de la façon dont elle est perçue. Une évolution notable en 1910 à Buenos Aires, précurseuse d'un changement, est mise en lumière. Ensuite, les sources disponibles à l'étude, rapports et catalogues, sont décrites, et les possibilités d'analyse expliquées. Puis, deux études de cas, Liège 1905 et Bruxelles 1910, sont menées, afin de donner un exemple de l'étude qu'il est possible d'entreprendre. Enfin, après avoir montré l'importance de l'exposition universelle dans l'histoire de la mode du début du vingtième siècle, c'est par un appel à d'autres études plus poussées sur le sujet que l'article se termine.At the Exposition Internationale des Arts Décoratifs in 1925 in Paris, haute couture is art. It was not at the universal exhibition in 1900, during which it was presented as an indsutry. During the first quarter of the twentieth century, its integration in universal and international exhibitions evolves, following its will to be celebrated as art, status which justifies its practices. This article demonstrates the importance, for the discipline of fashion history, of studying haute couture in universals exhibitions, so as to understand its definition at the time, suggesting directions and methodologies for the research. First of all, the position of haute couture, between art and industry, is discussed, studying the categories in which it was represented during the exhibitions, which indicate how it was percieved. A noteworthy change that happened in Buenos Aires in 1910, is highlighted. Then, the sources are described and the possible analysis explained. Following, two cases, Liège 1905 and Brussels 1910, are studied, so as to to give an example of the study that can be accomplished. Finally, after showing the importance of the universal exhibition in the history of fashion of the early twentieth century, the articles concludes with an encouragement to continue the research

Origine et évolution de la tolérance au zinc chez Arabidopsis halleri (Brassicaceae) (approches phénotypiques et génétiques)

La tolérance aux métaux lourds est la capacité des espèces métallophytes à se développer sur des sols pollués par les métaux. L'étude de ce caractère adaptatif exceptionnel engage aujourd'hui des technologies lourdes nécessitant l'emploi de quelques espèces modèles. La proximité de l'espèce pseudometallophyte tolérante au Zn et Cd Arabidopsis halleri (Brassicaceae) avec le modèle de la biologie végétale Arabidopsis thaliana offre l'opportunité d'exploiter les outils moléculaires développés chez A. thaliana. A. halleri est donc à son tour proposée comme espèce modèle pour l'étude des mécanismes génétiques et moléculaires de la tolérance aux métaux lourds chez les végétaux supérieurs. Cependant les connaissances disponibles sur l'écologie et l'évolution de l'espèce sont limitées. Pour une meilleure compréhension de l'origine et l'évolution de la tolérance au Zn chez A. halleri, ce travail proposait deux approches. Tout d'abord, évaluer la distribution des capacités de tolérance dans les populations de l'espèce en intégrant des populations métallicoles (M) recensées dans trois régions polluées du nord de l'Europe, et des populations non métallicoles (NM) réparties dans l'aire de distribution de l'espèce. Ensuite, décrire, à l'aide des approches contemporaines de la génétique des populations, la structure génétique de l'espèce, à l'échelle de l'Europe, pour donner un contexte génétique neutre à l'étude de la dynamique évolutive du caractère. L'analyse phénotypique de 33 populations confirme une tolérance constitutive, i.e. présente dans toutes les populations. Cependant, un polymorphisme quantitatif intra- et inter-population a été observé. Une tendance générale vers plus de tolérance a été notée chez les populations M.L'analyse de la distribution géographique d'une généalogie d'haplotypes identifiés par PCR-RFLP révèle des origines multiples et mutuellement indépendantes des populations M géographiquement distantes. L'analyse combinée de la structure des haplotypes chloroplastiques et de six microsatellites nucléaires montre clairement deux ensembles génétiques isolés par les Alpes et aux histoires phylogéographiques distinctes. Dans le groupe génétique au Nord des Alpes, les populations M forment un groupe hétérogène et ne se différencient des populations NM qu'à travers la distance géographique. L'origine d'une tolérance constitutive ne peut pas être déterminée par une étude intraspécifique. Des hypothèses sont néanmoins émises. L'observation d'un polymorphisme quantitatif atteste d'un potentiel génétique pour l'évolution du caractère au sein de l'espèce. La tolérance supérieure des populations M confirment une adaptation de ces populations aux sols pollués, en dépit de la tolérance constitutive. Les origines indépendantes des populations M géographiquement distantes interrogent la nature des mécanismes localement sélectionnées. Enfin, la similitude des génomes nucléaires aux locus neutres entre populations M et NM géographiquement proches posent la question des mécanismes microévolutifs du maintien des différences adaptatives et présente un contexte favorable à des approches de scan génomique.LILLE1-BU (590092102) / SudocSudocFranceF

Evolutionary dynamics of quantitative variation in an adaptive trait at the regional scale:The case of zinc hyperaccumulation in Arabidopsis halleri

Metal hyperaccumulation in plants is an ecological trait whose biological significance remains debated, in particular because the selective pressures that govern its evolutionary dynamics are complex. One of the possible causes of quantitative variation in hyperaccumulation may be local adaptation to metalliferous soils. Here, we explored the population genetic structure of Arabidopsis halleri at fourteen metalliferous and nonmetalliferous sampling sites in southern Poland. The results were integrated with a quantitative assessment of variation in zinc hyperaccumulation to trace local adaptation. We identified a clear hierarchical structure with two distinct genetic groups at the upper level of clustering. Interestingly, these groups corresponded to different geographic subregions, rather than to ecological types (i.e., metallicolous vs. nonmetallicolous). Also, approximate Bayesian computation analyses suggested that the current distribution of A. halleri in southern Poland could be relictual as a result of habitat fragmentation caused by climatic shifts during the Holocene, rather than due to recent colonization of industrially polluted sites. In addition, we find evidence that some nonmetallicolous lowland populations may have actually derived from metallicolous populations. Meanwhile, the distribution of quantitative variation in zinc hyperaccumulation did separate metallicolous and nonmetallicolous accessions, indicating more recent adaptive evolution and diversifying selection between metalliferous and nonmetalliferous habitats. This suggests that zinc hyperaccumulation evolves both ways—towards higher levels at nonmetalliferous sites and lower levels at metalliferous sites. Our results open a new perspective on possible evolutionary relationships between A. halleri edaphic types that may inspire future genetic studies of quantitative variation in metal hyperaccumulation

Evolutionary dynamics of quantitative variation in an adaptive trait at the regional scale:The case of zinc hyperaccumulation in Arabidopsis halleri

Metal hyperaccumulation in plants is an ecological trait whose biological significance remains debated, in particular because the selective pressures that govern its evolutionary dynamics are complex. One of the possible causes of quantitative variation in hyperaccumulation may be local adaptation to metalliferous soils. Here, we explored the population genetic structure of Arabidopsis halleri at fourteen metalliferous and nonmetalliferous sampling sites in southern Poland. The results were integrated with a quantitative assessment of variation in zinc hyperaccumulation to trace local adaptation. We identified a clear hierarchical structure with two distinct genetic groups at the upper level of clustering. Interestingly, these groups corresponded to different geographic subregions, rather than to ecological types (i.e., metallicolous vs. nonmetallicolous). Also, approximate Bayesian computation analyses suggested that the current distribution of A. halleri in southern Poland could be relictual as a result of habitat fragmentation caused by climatic shifts during the Holocene, rather than due to recent colonization of industrially polluted sites. In addition, we find evidence that some nonmetallicolous lowland populations may have actually derived from metallicolous populations. Meanwhile, the distribution of quantitative variation in zinc hyperaccumulation did separate metallicolous and nonmetallicolous accessions, indicating more recent adaptive evolution and diversifying selection between metalliferous and nonmetalliferous habitats. This suggests that zinc hyperaccumulation evolves both ways—towards higher levels at nonmetalliferous sites and lower levels at metalliferous sites. Our results open a new perspective on possible evolutionary relationships between A. halleri edaphic types that may inspire future genetic studies of quantitative variation in metal hyperaccumulation

Variability of zinc tolerance among and within populations of the pseudometallophyte species Arabidopsis halleri and possible role of directional selection.

We estimated the level of quantitative polymorphism for zinc (Zn) tolerance in neighboring metallicolous and nonmetallicolous populations of Arabidopsis halleri and tested the hypothesis that divergent selection has shaped this polymorphism. A short-term hydroponic test was used to capture the quantitative polymorphism present between edaphic types, among and within populations. We measured six morphological and physiological traits on shoots and roots to estimate the response of A. halleri to Zn. In order to assess the adaptive value of Zn tolerance polymorphism, we compared differentiation of quantitative traits with that of molecular markers. Zinc tolerance of metallicolous populations was, on average, higher than that of nonmetallicolous populations according to the morphological and physiological traits measured. Phenotypic variability within edaphic types was very high and mainly explained by polymorphism among individuals within populations. Genetic differentiation for photosystem II yield of leaves (a measure of photosynthetic efficiency) was greater than the differentiation for microsatellite and thus, probably shaped by divergent selection. Overall, these results suggest that, in the sampled populations, Zn tolerance has been increased in metallicolous populations through selection on standing genetic variation within local nonmetallicolous ancestral populations.Journal ArticleResearch Support, Non-U.S. Gov'tFLWINinfo:eu-repo/semantics/publishe

Habitat heterogeneity in the pseudometallophyte Arabidopsis halleri and its structuring effect on natural variation of zinc and cadmium hyperaccumulation

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PeerJ, 2016, Vol. 4, art. no e1645

The present study aimed to investigate phylogeographical patterns present within A. halleri in Central Europe. 1,281 accessions sampled from 52 populations within the investigated area were used in the study of genetic variation based on chloroplast DNA. Over 500 high-quality species occurrence records were used in ecological niche modelling experiments. We evidenced the presence of a clear phylogeographic structure within A. halleri in Central Europe. Our results showed that two genetically different groups of populations are present in western and eastern part of the Carpathians. The hypothesis of the existence of a glacial refugium in the Western Carpathians adn the Bohemian Forest cannot be rejected from our data. It seems, however, that the evidence collected during the present study is not conclusive. The area of Sudetes was colonised after LGM probably by migrants from the Bohemian Forest