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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

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...

Université de Fribourg

Recombinant hybrids retain heterozygosity at many loci: new insights into the genomics of reproductive isolation in Populus

Lindtke, Dorothea ; Buerkle, C. Alex ; Barbará, Thelma ; Heinze, Berthold ; Castiglione, Stefano ; Bartha, Denes ; Lexer, Christian

In: Molecular Ecology, 2012, p. -

The maintenance of species barriers in the face of gene flow is often thought to result from strong selection against intermediate genotypes, thereby preserving genetic differentiation. Most speciation genomic studies thus aim to identify exceptionally divergent loci between populations, but divergence will be affected by many processes other than reproductive isolation (RI) and speciation....

Université de Fribourg

Molecular phylogenetics of the Brazilian giant bromeliads (Alcantarea, Bromeliaceae): implications for morphological evolution and biogeography

Versieux, Leonardo M. ; Barbará, Thelma ; Wanderley, Maria das Graças Lapa ; Calvente, Alice ; Fay, Michael F. ; Lexer, Christian

In: Molecular Phylogenetics and Evolution, 2012, p. -

The genus Alcantarea comprises near 30 species endemic to rocky outcrops from eastern Brazil. Most species are ornamental and several are threatened due to habitat loss and over collection. In this paper we examine the phylogenetics of Alcantarea and its relationship with the Brazilian members of Vriesea, a genus of which Alcantarea has been treated as a subgenus. We discuss the morphological...

Université de Fribourg

Genetic analysis of post-mating reproductive barriers in hybridizing European Populus species

Macaya-Sanz, David ; Suter, Leonie ; Joseph, Jeffrey A. ; Barbará, Thelma ; Alba, N. ; González-Martínez, S. C. ; Widmer, Alex ; Lexer, Christian

In: Heredity, 2011, vol. 107, p. 478–486

Molecular genetic analyses of experimental crosses provide important information on the strength and nature of post-mating barriers to gene exchange between divergent populations, which are topics of great interest to evolutionary geneticists and breeders. Although not a trivial task in long-lived organisms such as trees, experimental interspecific recombinants can sometimes be created through...

Université de Fribourg

Sympatric bromeliad species (Pitcairnia spp.) facilitate tests of mechanisms involved in species cohesion and reproductive isolation in Neotropical inselbergs

Palma-Silva, Clarisse ; Wendt, T. ; Pinheiro, Fábio ; Barbará, Thelma ; Fay, Michael F. ; Cozzolino, Salvatore ; Lexer, Christian

In: Molecular Ecology, 2011, vol. 20, no. 15, p. 3185–3201

The roles of intra- and interspecific gene flow in speciation and species evolution are topics of great current interest in molecular ecology and evolutionary biology. Recent modelling studies call for new empirical data to test hypotheses arising from the recent shift from a ‘whole-genome reproductive isolation’ view to a ‘genic’ view of species and speciation. Particularly scarce (and...

Université de Fribourg

Genomic admixture analysis in european Populus spp. reveals unexpected patterns of reproductive isolation and mating

Lexer, Christian ; Joseph, Jeffrey A. ; Loo, Marcela van ; Barbará, Thelma ; Heinze, Berthold ; Bartha, Denes ; Castiglione, Stefano ; Fay, Michael F. ; Buerkle, C. Alex

In: Genetics, 2010, vol. 186, p. 699–712

Admixture between genetically divergent populations facilitates genomic studies of the mechanisms involved in adaptation, reproductive isolation and speciation, including mapping of the loci involved in these phenomena. Little is known about how pre- and postzygotic barriers will affect the prospects of 'admixture mapping' in wild species. We have studied 93 mapped genetic markers...

Université de Fribourg

Range-wide patterns of nuclear and chloroplast DNA diversity in Vriesea gigantea (Bromeliaceae), a neotropical forest species

Palma-Silva, Clarisse ; Lexer, Christian ; Paggi, G. M. ; Barbará, Thelma ; Bered, F. ; Bodanese-Zanettini, M. H.

In: Heredity, 2009, vol. 103, p. 503–512

The processes that have shaped the extraordinary species diversity in neotropical rainforests are poorly understood, and knowledge about the patterns of genetic diversity across species' ranges is scarce, in contrast to other regions of the globe. We have conducted a range-wide study of genetic diversity in a plant endemic to the Brazilian Atlantic Rainforest, Vriesea gigantea (Bromeliaceae),...

Université de Fribourg

Genetic relationships and variation in reproductive strategies in four closely related bromeliads adapted to neotropical ‘inselbergs’: Alcantarea glaziouana, A. regina, A. geniculata and A. imperialis (Bromeliaceae)

Barbará, Thelma ; Martinelli, Gustavo ; Palma-Silva, Clarisse ; Fay, Michael F. ; Mayo, Simon ; Lexer, Christian

In: Annals of Botany, 2009, vol. 103, no. 1, p. 65-77

Background and Aims: Bromeliads (Bromeliaceae) adapted to rock outcrops or ‘inselbergs’ in neotropical rain forests have been identified as suitable plant models for studying population divergence and speciation during continental plant radiations. Little is known about genetic relationships and variation in reproductive strategies within and among inselberg-adapted species, yet knowledge of...