HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (43) Citing Articles via Google Scholar Google Scholar Articles by Schwarzbach, A. E. Articles by Rieseberg, L. H. Search for Related Content PubMed PubMed Citation Articles by Schwarzbach, A. E. Articles by Rieseberg, L. H. Agricola Articles by Schwarzbach, A. E. Articles by Rieseberg, L. H.

Transgressive character expression in a hybrid sunflower species¹

² Indiana University, Department of Biology, Bloomington, Indiana 47405 USA; ⁴ University of Georgia, Department of Botany, Athens, Georgia 30602 USA

Diploid hybrid lineages often are ecologically distinct from their parental species. However, it is unclear whether this niche divergence is typically achieved via hybrid intermediacy, a mixture of parental traits, and/or the evolution of extreme (transgressive) morphological and ecophysiological features. Here we compare an extensively studied hybrid sunflower species, Helianthus anomalus, with its putative parents, H. annuus and H. petiolaris, for 41 morphological and 12 ecophysiological traits. Helianthus anomalus was morphologically intermediate for one trait (2.4%), parental-like for 23 traits (56.1%), and transgressive for 17 traits (41.5%). For ecophysiological traits, H. anomalus was not significantly different from one or both parents for nine traits (75%), and was transgressive for the remaining three (25%). Thus, H. anomalus appears to be a mosaic of parental-like and transgressive phenotypes. Although the fitness effects of the transgressive characters are not yet known, many of these characters are consistent with adaptations reported for other sand dune plants. Genetic studies are currently underway to ascertain whether these extreme characters arose as a direct byproduct of hybridization or whether they evolved via mutational divergence.

Key Words: adaptations • carbon isotope ratios • Helianthus • hybridization • photosynthesis • speciation • transgressive segregation • water-use efficiency

This article has been cited by other articles:

				C. A. Wu and D. R. Campbell Leaf physiology reflects environmental differences and cytoplasmic background in Ipomopsis (Polemoniaceae) hybrids Am. J. Botany, November 1, 2007; 94(11): 1804 - 1812. [Abstract] [Full Text] [PDF]

				J. Lihova, J. Kucera, M. Perny, and K. Marhold Hybridization between Two Polyploid Cardamine (Brassicaceae) Species in North-western Spain: Discordance Between Morphological and Genetic Variation Patterns Ann. Bot., June 1, 2007; 99(6): 1083 - 1096. [Abstract] [Full Text] [PDF]

				L. C. Brouillette, D. M. Rosenthal, L. H. Rieseberg, C. Lexer, R. L. Malmberg, and L. A. Donovan Genetic Architecture of Leaf Ecophysiological Traits in Helianthus J. Hered., March 1, 2007; 98(2): 142 - 146. [Abstract] [Full Text] [PDF]

				S. A. Church and D. R. Taylor Speciation and hybridization among Houstonia (Rubiaceae) species: the influence of polyploidy on reticulate evolution Am. J. Botany, August 1, 2005; 92(8): 1372 - 1380. [Abstract] [Full Text] [PDF]

				N. B. Langlade, X. Feng, T. Dransfield, L. Copsey, A. I. Hanna, C. Thebaud, A. Bangham, A. Hudson, and E. Coen Evolution through genetically controlled allometry space PNAS, July 19, 2005; 102(29): 10221 - 10226. [Abstract] [Full Text] [PDF]

				B. L. Gross and L. H. Rieseberg The Ecological Genetics of Homoploid Hybrid Speciation J. Hered., May 1, 2005; 96(3): 241 - 252. [Abstract] [Full Text] [PDF]

				M. E. Welch and L. H. Rieseberg Habitat divergence between a homoploid hybrid sunflower species, Helianthus paradoxus (Asteraceae), and its progenitors Am. J. Botany, March 1, 2002; 89(3): 472 - 478. [Abstract] [Full Text] [PDF]