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Université de Fribourg

Molecular ecology studies of species radiations: current research gaps, opportunities and challenges

la Harpe, Marylaure de ; Paris, Margot ; Karger, Dirk N. ; Rolland, Jonathan ; Kessler, Michael ; Salamin, Nicolas ; Lexer, Christian

In: Molecular Ecology, 2017, p. -

Understanding the drivers and limits of species radiations is a crucial goal of evolutionary genetics and molecular ecology, yet research on this topic has been hampered by the notorious difficulty of connecting micro- and macroevolutionary approaches to studying the drivers of diversification. To chart the current research gaps, opportunities and challenges of molecular ecology approaches to...

Université de Fribourg

Adaptive evolution and segregating load contribute to the genomic landscape of divergence in two tree species connected by episodic gene flow

Christe, Camille ; Stölting, Kai N. ; Paris, Margot ; Fraїsse, Christelle ; Bierne, Nicolas ; Lexer, Christian

In: Molecular Ecology, 2017, vol. 26, no. 1, p. 59–76

Speciation often involves repeated episodes of genetic contact between divergent populations before reproductive isolation (RI) is complete. Whole-genome sequencing (WGS) holds great promise for unravelling the genomic bases of speciation. We have studied two ecologically divergent, hybridizing species of the ‘model tree’ genus Populus (poplars, aspens, cottonwoods), Populus alba and P....

Université de Fribourg

Causes and consequences of large clonal assemblies in a poplar hybrid zone

Macaya-Sanz, David ; Heuertz, Myriam ; Lindtke, Dorothea ; Vendramin, Giovanni G. ; Lexer, Christian ; González-Martínez, andSantiago C.

In: Molecular Ecology, 2016, vol. 25, no. 21, p. 5330–5344

Asexual reproduction is a common and fundamental mode of reproduction in plants. Although persistence in adverse conditions underlies most known cases of clonal dominance, proximal genetic drivers remain unclear, in particular for populations dominated by a few large clones. In this study, we studied a clonal population of the riparian tree Populus alba in the Douro river basin (northwestern...

Université de Fribourg

Gene flow and diversification in a species complex of Alcantarea inselberg bromeliads

Lexer, Christian ; Marthaler, Fabienne ; Humbert, Sarah ; Barbará, Thelma ; Harpe, Marylaure de la ; Bossolini, Eligio ; Paris, Margot ; Martinelli, Gustavo ; Versieux, Leonardo M.

In: Botanical Journal of the Linnean Society, 2016, vol. 181, no. 3, p. 505–520

Inselberg-adapted species of bromeliads (Bromeliaceae) have been suggested as model systems for understanding the evolutionary genetics of species complexes and radiations in terrestrial, island-like environments. Bromeliads are particularly suitable for addressing the potential roles of interspecific gene exchange during plant speciation and radiation. We have studied populations of five...

Université de Fribourg

Selection against recombinant hybrids maintains reproductive isolation in hybridizing Populus species despite F1 fertility and recurrent gene flow

Christe, Camille ; Stölting, Kai N. ; Bresadola, Luisa ; Fussi, Barbara ; Heinze, Berthold ; Wegmann, Daniel ; Lexer, Christian

In: Molecular Ecology, 2016, p. -

Natural hybrid zones have proven to be precious tools for understanding the origin and maintenance of reproductive isolation (RI) and therefore species. Most available genomic studies of hybrid zones using whole or partial genome resequencing approaches have focused on comparisons of the parental source populations involved in genome admixture, rather than exploring fine-scale patterns of...

Université de Fribourg

Mating system variation and assortative mating of sympatric bromeliads (Pitcairnia spp.) endemic to neotropical inselbergs

Palma-Silva, Clarisse ; Cozzolino, Salvatore ; Paggi, Gecele Matos ; Lexer, Christian ; Wendt, Tânia

In: American Journal of Botany, 2015, vol. 102, no. 5, p. 758–764

Premise of the study: The mating system is an important component of the complex set of reproductive isolation barriers causing plant speciation. However, empirical evidence showing that the mating system may promote reproductive isolation in co-occurring species is limited. The mechanisms by which the mating system can act as a reproductive isolation barrier are also largely unknown. Methods:...

Université de Fribourg

Patterns of genetic diversity and differentiation in resistance gene clusters of two hybridizing European Populus species

Casey, Céline ; Stölting, Kai N. ; Barbará, Thelma ; González-Martínez, Santiago C. ; Lexer, Christian

In: Tree Genetics & Genomes, 2015, vol. 11, no. 4, p. 1–12

Resistance genes (R-genes) are essential for long-lived organisms such as forest trees, which are exposed to diverse herbivores and pathogens. In short-lived model species, R-genes have been shown to be involved in species isolation. Here, we studied more than 400 trees from two natural hybrid zones of the European Populus species Populus alba and Populus tremula for microsatellite markers...