Article

Download article 		Title: Hybridization and introgression across different ploidy levels in the Neotropical orchids Epidendrum fulgens and E. puniceoluteum (Orchidaceae)
Author: Pinheiro, Fábio; De Barros, Fábio; Palma-silva, Clarisse; Meyer, Diogo; Fay, Michael F.; Suzuki, Rogério M.; Lexer, Christian; Cozzolino, Salvatore
Year: 2010
Is part of: MOLECULAR ECOLOGY, v. 19, p. 3981 - 3994
DOI: https://doi.org/10.1111/j.1365-294X.2010.04780.x

Citation: Pinheiro, Fábio; De Barros, Fábio; Palma-silva, Clarisse; Meyer, Diogo; Fay, Michael F.; Suzuki, Rogério M.; Lexer, Christian; Cozzolino, Salvatore; Hybridization and introgression across different ploidy levels in the Neotropical orchids Epidendrum fulgens and E. puniceoluteum (Orchidaceae). MOLECULAR ECOLOGY, v.19, p. 3981-3994, 2010

Abstract: 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.

Keywords: Especiação; evolução; Fluxo gênico; Hibridação; introgressão; Isolamento reprodutivo;
Subjects: CIENCIAS_BIOLOGICAS; Isolamento reprodutivo;

Funding: We thank V. Tranchida-Lombardo and R. Rinaldi for helping in the laboratory, D. Fuhro, C. M. Zanella and S. Koehler for help during field work, and Alex Widmer, Eduardo L. Borba, Joao M. B. Alexandrino, Maria I. Zucchi, Lucia G. Lohmann, Richard J. Abbott and three anonymous referees for valuable comments. Funding for this study was provided by grants from the Prance Fellowship in Neotropical Botany under the Kew Latin American Research Fellowship Programme (KLARF) to FP, Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq-471929/2006-9) and Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP-06/54189-3) to FB. FP received fellowship from CNPq and CAPES and FB receives a productivity grant from CNPq. 		Financed by: