Hybridization and introgression across different ploidy levels in the Neotropical orchids Epidendrum fulgens and E-puniceoluteum (Orchidaceae)

Autor(es)

Pinheiro, Fabio ^{[1, 2]} ; de Barros, Fabio ^[2] ; Palma-Silva, Clarisse ^{[2, 3]} ; Meyer, Diogo ^[4] ; Fay, Michael F. ^[3] ; Suzuki, Rogerio M. ^[2] ; Lexer, Christian ^{[3, 5]} ; Cozzolino, Salvatore ^[6]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Biociencias, Dept Bot, BR-05508900 Sao Paulo - Brazil

^[2] Inst Bot, BR-04301012 Sao Paulo - Brazil

^[3] Royal Bot Gardens Kew, Jodrell Lab, Richmond TW9 3DS, Surrey - England

^[4] Univ Sao Paulo, Inst Biociencias, Dept Genet & Biol Evolut, BR-05508900 Sao Paulo - Brazil

^[5] Univ Fribourg, Unit Ecol & Evolut, Dept Biol, CH-1700 Fribourg - Switzerland

^[6] Univ Naples Federico 2, Dipartimento Biol Strutturale & Funz, I-80100 Naples - Italy

• Tipo de documento: Artigo Científico
• Fonte: Molecular Ecology; v. 19, n. 18, p. 3981-3994, SEP 2010.
• Citações Web of Science: 50

Resumo

The hypothesis of gene flow between species with large differences in chromosome numbers has rarely been tested in the wild, mainly because species of different ploidy are commonly assumed to be reproductively isolated from each other because of instantaneous and strong postzygotic barriers. In this study, a broad-scale survey of molecular variation was carried out between two orchid species with different ploidy levels: Epidendrum fulgens (2n = 2x = 24 chromosomes) and Epidendrum puniceoluteum (2n = 4x = 52 chromosomes). To test the strength of their reproductive barriers, we investigated the distribution of genetic variation in sympatric and allopatric populations of these two species and conducted crossing experiments. Nuclear and plastid microsatellite loci were used to genotype 463 individuals from eight populations across the geographical range of both species along the Brazilian coastal plain. All six sympatric populations analysed presented hybrid zones, indicating that hybridization between E. fulgens and E. puniceoluteum is a common phenomenon. Bayesian assignment analysis detected the presence of F(1) and F(2) individuals and also signs of introgression, demonstrating a high potential for interspecific gene flow. Introgression occurs preferentially from E. fulgens to E. puniceoluteum. Pure parental individuals of both species display strong genotype-habitat associations, indicating that environment-dependent selection could be acting in all hybrid zones. This study suggests that hybridization and introgression are evolutionary processes playing a role in the diversification of Epidendrum and indicates the importance of investigations of hybrid zones in understanding reproductive barriers and speciation processes in Neotropical orchid species. (AU)

• Processo FAPESP: 06/54189-3 - Implicações taxonômicas da estrutura genética de populações naturais de E. cinnabarinum Salzm., E. denticulatum Barb. Rodr. e E. fulgens Brongn.
• Beneficiário: Fábio de Barros
• Modalidade de apoio: Auxílio à Pesquisa - Regular