title: Transgressive phenotypes and generalist pollination in the floral evolution of Nicotiana polyploids.
abstract: Polyploidy is an important driving force in angiosperm evolution, and much research has focused on genetic, epigenetic and transcriptomic responses to allopolyploidy. Nicotiana is an excellent system in which to study allopolyploidy because half of the species are allotetraploids of different ages, allowing us to examine the trajectory of floral evolution over time. Here, we study the effects of allopolyploidy on floral morphology in Nicotiana, using corolla tube measurements and geometric morphometrics to quantify petal shape. We show that polyploid morphological divergence from the intermediate phenotype expected (based on progenitor morphology) increases with time for floral limb shape and tube length, and that most polyploids are distinct or transgressive in at least one trait. In addition, we show that polyploids tend to evolve shorter and wider corolla tubes, suggesting that allopolyploidy could provide an escape from specialist pollination via reversion to more generalist pollination strategies.
authors: School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK.|Jodrell Laboratory, Royal Botanic Gardens, Kew, Richmond TW9 3DS, UK.|Natural History Museum, London SW7 5BD, UK.
authors: Elizabeth W
authors: EW
authors: McCarthy
authors: Jodrell Laboratory, Royal Botanic Gardens, Kew, Richmond TW9 3DS, UK.
authors: Mark W
authors: MW
authors: Chase
authors: Natural History Museum, London SW7 5BD, UK.
authors: Sandra
authors: S
authors: Knapp
authors: Department of Botany and Plant Sciences, University of California, Riverside, California 92521, USA.
authors: Amy
authors: A
authors: Litt
authors: School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK.
authors: Andrew R
authors: AR
authors: Leitch
authors: School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK.
authors: Steven C
authors: SC
authors: Le Comber
mesh_terms: D005075:Biological Evolution; D035264:Flowers / Q000033:anatomy & histology* / Q000235:genetics; D010641:Phenotype; D054817:Pollination; D011123:Polyploidy; D014026:Nicotiana / Q000033:anatomy & histology / Q000235:genetics / Q000502:physiology*