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The Lexer Lab |
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Molecular
ecology
& evolutionary genetics group |
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Thelma Barbará |
Post-doctoral researcher in plant evolutionary genetics |
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I am interested in speciation, more
specifically in the genetic basis of ecological species differences. I
am currently investigating the evolution of species barriers in
northern hemisphere trees of the genus Populus
and in tropical bromeliads
adapted to Inselbergs (granitic rock outcrops). Towards ‘admixture mapping’ of fitness-related trait differences in European Populus I am currently involved in the core project of our lab, which is aimed at ‘admixture mapping’ in natural hybrid zones of Populus alba and P. tremula to study the genetics of fitness-related and adaptively important traits. Knowing the genetic basis of ecological species differences is relevant to several key topics in ecology & evolution, including the likelihood of ecological speciation, the within-species consequences of introgression, and the potential impact of heritable traits in keystone or foundation species on biotic interactions. This work involves population genomic analysis of PCR-based, mapped molecular genetic markers and ecologically relevant characters in trees from multiple replicate hybrid zones in Europe. 
Molecular population genetics of neotropical Bromeliads adapted to inselbergs in the Atlantic rainforest of Brazil The inselbergs of the Brazilian Atlantic Rain Forest form
terrestrial "islands" that are isolated from the surrounding forest by
steep gradients in humidity, temperature and irradiation, and by
drastic changes in soil substrates. Bromeliads (Bromeliaceae) are
particularly well represented among plants adapted to the extreme
growing conditions on inselbergs.
During my PhD project I investigated the molecular population genetics of four members of the Alcantarea species complex endemic to inselbergs of coastal Atlantic Brazil, which includes Alcantarea imperialis, A. geniculata, A. glaziouana and A. regina. Our initial aim was to study genetic variability at nuclear DNA microsatellites and plastid DNA markers to address fundamental questions regarding the breeding system, metapopulation dynamics, and distribution of genetic diversity across a highly fragmented landscape. Our recently funded project will allow us to investigate ecological processes directly involved in speciation in these inselberg species, including prezygotic barriers mediated by pollinator behaviour.  Recent Publications: for non-scientific reading refer to the link at the end of this page Genetic analysis of post-mating reproductive barriers in hybridizing European Populus species. Macaya-Sanz D, Suter L, Joseph J, Barbará T, Alba N, Gonzalez-Martínez SC, Widmer A, Lexer C. Heredity, published online: 18 May 2011. doi:10.1038/hdy.2011.35 Sympatric bromeliad species (Pitcairnia spp.) facilitate tests of mechanisms involved in species cohesion and reproductive isolation in Neotropical inselbergs. Palma-Silva C, Wendt T, Pinheiro F, Barbará T, Fay MF, Cozzolino S, Lexer C. Molecular Ecology, published online: 15 Jun 2011. doi: 10.1111/j.1365-294X.2011.05143.x Genomic admixture analysis in European Populus spp. reveals unexpected patterns of reproductive isolation and mating. Lexer C, Joseph JA, van Loo M, Barbará T, Heinze B, Bartha D, Castiglione S, Fay MF, Buerkle CA. Genetics, 186: 699-712 Range-wide patterns of nuclear and chloroplast DNA diversity in Vriesea gigantea (Bromeliaceae), a neotropical forest species. C Palma-Silva, C Lexer, GM Paggi, T Barbará, F Bered and MH Bodanese-Zanettini. Heredity advance online publication 9 September 2009; doi: 10.1038/hdy.2009.116 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 T, Martinelli G, Palma-Silva C, Fay MF, Mayo S, and Lexer C. Annals of Botany, 2009, 103:65-77. Within-population spatial genetic structure in four naturally fragmented species of a neotropical inselberg radiation, Alcantarea imperialis, A. geniculata, A. glaziouana and A. regina (Bromeliaceae). Barbará T, Lexer C, Martinelli G, Mayo S, Fay MF, and Heuertz M. Heredity, 2008, 101:285-296. Cross-species transfer of nuclear microsatellite markers: potential and limitations. Barbará T, Palma-Silva C, Paggi GM, Bered F, Fay MF, and Lexer C. Molecular Ecology, 2007, 16:3759-3767. Population differentiation and species cohesion in two closely related plants adapted to neotropical high-altitude ‘inselbergs’, Alcantarea imperialis and A. geniculata (Bromeliaceae). Barbará T, Martinelli G, Fay MF, Mayo SJ, and Lexer C. Molecular Ecology, 2007, 16:1981-1992. A set of polymorphic microsatellite loci for Vriesea gigantea and Alcantarea imperialis (Bromeliaceae) and cross-amplification in other bromeliad species. Palma-Silva C, Cavallari MM, Barbará T, Lexer C, Gimenes MA, Bered F, and Zanettini MH. Molecular Ecology Notes, 2007 , 7:654-657. Towards forest community and ecosystem genomics. Lexer C, Van Loo M, and Barbará T. New Phytologist, 2007, 173:673-676. Non Scientific reading on Bromeliads How can conservationists maintain genetic diversity among plants in fragmented habitats? Research into bromeliads in the forests of Brazil... (Kew Magazine 2007) The Bromeliads of the Atlantic Forest (Scientific American 2000)
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