title: Evidence for reproductive isolate selection in Mediterranean orchids: karyotype differences compensate for the lack of pollinator specificity.
abstract: Mediterranean orchids of the subtribe Orchidinae are highly diverse and display a range of fascinating pollination strategies. Based on observations that orchid-pollinator relationships are often highly specialized and species specific, Darwin and others have argued that selection for different pollinators has been the driving force behind the evolutionary diversification of orchids. This may be true for orchids that attract different, specialized pollinators that act as prezygotic reproductive barriers. It is, however, not clear how closely related co-flowering Mediterranean orchids that share pollinators survive the challenge of sympatry. We show that species pairs with a generalized pool of pollinators have significantly more divergent karyotypes compared with species pairs with different pollinators. These results show that karyotype differences that act as postzygotic reproductive barriers may have played an important role in the evolution of Mediterranean orchid diversity.
authors.affiliation: Dipartimento di Biologia Vegetale, Università degli Studi di Napoli Federico II, Via Foria 223, 1-80139 Naples, Italy. cozzolin@unina.it
authors.forename: Salvatore
authors.initials: S
authors.lastname: Cozzolino
authors.forename: Saverio
authors.initials: S
authors.lastname: D'Emerico
authors.forename: Alex
authors.initials: A
authors.lastname: Widmer
mesh_terms: D000818:Animals; D032461:Chromosomes, Plant / Q000235:genetics*; D004275:DNA, Ribosomal / Q000235:genetics; D019143:Evolution, Molecular; D007313:Insecta / Q000502:physiology; D007621:Karyotyping; D019083:Mediterranean Region; D029595:Orchidaceae / Q000235:genetics* / Q000502:physiology; D010802:Phylogeny; D011058:Pollen / Q000502:physiology; D012098:Reproduction / Q000502:physiology; D012641:Selection, Genetic; D013045:Species Specificity; D013559:Symbiosis
chemical_list: D004275:DNA, Ribosomal