title: Interploidy hybridization in sympatric zones: the formation of Epidendrum fulgens × E. puniceoluteum hybrids (Epidendroideae, Orchidaceae).
abstract: Interspecific hybridization is a primary cause of extensive morphological and chromosomal variation and plays an important role in plant species diversification. However, the role of interploidal hybridization in the formation of hybrid swarms is less clear. Epidendrum encompasses wide variation in chromosome number and lacks strong premating barriers, making the genus a good model for clarifying the role of chromosomes in postzygotic barriers in interploidal hybrids. In this sense, hybrids from the interploidal sympatric zone between E. fulgens (2n = 2x = 24) and E. puniceoluteum (2n = 4x = 56) were analyzed using cytogenetic techniques to elucidate the formation and establishment of interploidal hybrids. Hybrids were not a uniform group: two chromosome numbers were observed, with the variation being a consequence of severe hybrid meiotic abnormalities and backcrossing with E. puniceoluteum. The hybrids were triploids (2n = 3x = 38 and 40) and despite the occurrence of enormous meiotic problems associated with triploidy, the hybrids were able to backcross, producing successful hybrid individuals with broad ecological distributions. In spite of the nonpolyploidization of the hybrid, its formation is a long-term evolutionary process rather than a product of a recent disturbance, and considering other sympatric zones in Epidendrum, these events could be recurrent.
authors.affiliation: Laboratório de Biossistemática e Evolução de Plantas, Departamento de Biologia Vegetal, Instituto de Biologia, Universidade Estadual de Campinas/UNICAMP Campinas, São Paulo, Brasil ; Programa de Pós Graduação em Evolução e Diversidade, Universidade Federal do ABC/UFABC Santo André, São Paulo, Brasil.
authors.forename: Ana P
authors.initials: AP
authors.lastname: Moraes
authors.forename: Mariana
authors.initials: M
authors.lastname: Chinaglia
authors.forename: Clarisse
authors.initials: C
authors.lastname: Palma-Silva
authors.forename: Fábio
authors.initials: F
authors.lastname: Pinheiro
keywords: Epidendrum; GISH; hybrid zone; interploidy crossing; karyotype; orchids; plant speciation