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 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 (63) Citing Articles via Google Scholar Google Scholar Articles by Armbruster, W. S. Articles by Velásquez Runk, J. L. Search for Related Content PubMed Articles by Armbruster, W. S. Articles by Velásquez Runk, J. L. Agricola Articles by Armbruster, W. S. Articles by Velásquez Runk, J. L.

Covariance and decoupling of floral and vegetative traits in nine Neotropical plants: a re-evaluation of Berg's correlation-pleiades concept¹

^a Department of Botany, Norwegian University of Science and Technology, N-7034 Trondheim, Norway, and Institute of Arctic Biology, University of Alaska, Fairbanks, Alaska 99775-7000; and ^b Department of Biology, University of Massachusetts, Amherst, Massachusetts 01003-5810; and ^c Institute for Environmental Studies, University of Wisconsin, Madison, Wisconsin 53706; and ^d Department of Biology, University of Missouri, 8001 Natural Bridge Rd, St. Louis, Missouri 63121; and ^e School of Environment, Duke University, Durham, North Carolina 27708

Nearly forty years ago R. L. Berg proposed that plants with specialized pollination ecology evolve genetic and developmental systems that decouple floral morphology from phenotypic variation in vegetative traits. These species evolve separate floral and vegetative trait clusters, or as she termed them, "correlation pleiades." The predictions of this hypothesis have been generally supported, but only a small sample of temperate-zone herb and grass species has been tested. To further evaluate this hypothesis, especially its applicability to plants of other growth forms, we examined the patterns of phenotypic variation and covariation of floral and vegetative traits in nine species of Neotropical plants. We recognized seven specific predictions of Berg's hypothesis. Our results supported some predictions but not others. Species with specialized pollination systems usually had floral traits decoupled (weak correlation; Canna and Eichornia) or buffered (relationship with shallow proportional slope; Calathea and Canna) from variation in vegetative traits. However, the same trend was also observed in three species with unspecialized pollination systems (Echinodorus, Muntingia, and Wedelia). One species with unspecialized pollination (Croton) and one wind-pollinated species (Cyperus) showed no decoupling or buffering, as predicted. While species with specialized pollination usually showed lower coefficients of variation for floral traits than vegetative traits (as predicted), the same was also true of species with unspecialized or wind pollination (unlike our prediction). Species with specialized pollination showed less variation in floral traits than did species with unspecialized or wind pollination, as predicted. However, the same was true of the corresponding vegetative traits, which was unexpected. Also in contrast to our prediction, plants with specialized pollination systems did not exhibit tighter phenotypic integration of floral characters than did species with generalized pollination systems. We conclude that the patterns of morphological integration among floral traits and between floral and vegetative traits tend to be species specific, not easily predicted from pollination ecology, and generally more complicated than R. L. Berg envisaged.

Key Words: adaptation • correlated evolution • correlation pleiades • evolution • floral traits • genetic correlation • natural selection • pollination • quantitative genetics

This article has been cited by other articles:

				D. R. Campbell Using phenotypic manipulations to study multivariate selection of floral trait associations Ann. Bot., June 1, 2009; 103(9): 1557 - 1566. [Abstract] [Full Text] [PDF]

				M. van Kleunen, A. Meier, M. Saxenhofer, and M. Fischer Support for the predictions of the pollinator-mediated stabilizing selection hypothesis J Plant Ecol, September 1, 2008; 1(3): 173 - 178. [Abstract] [Full Text] [PDF]

				V. R. Chalcoff, C. Ezcurra, and M. A. Aizen Uncoupled Geographical Variation between Leaves and Flowers in a South-Andean Proteaceae Ann. Bot., July 1, 2008; 102(1): 79 - 91. [Abstract] [Full Text] [PDF]

				J. S. Miller and P. K. Diggle Correlated evolution of fruit size and sexual expression in andromonoecious Solanum sections Acanthophora and Lasiocarpa (Solanaceae) Am. J. Botany, October 1, 2007; 94(10): 1706 - 1715. [Abstract] [Full Text] [PDF]

				I. A. Anderson and J. W. Busch Relaxed pollinator-mediated selection weakens floral integration in self-compatible taxa of Leavenworthia (Brassicaceae) Am. J. Botany, June 1, 2006; 93(6): 860 - 867. [Abstract] [Full Text] [PDF]

				S. J. Mazer, H. Paz, and M. D. Bell Life history, floral development, and mating system in Clarkia xantiana (Onagraceae): do floral and whole-plant rates of development evolve independently? Am. J. Botany, December 1, 2004; 91(12): 2041 - 2050. [Abstract] [Full Text] [PDF]

				A. M. Sanchez-Lafuente Floral variation in the generalist perennial herb Paeonia broteroi (Paeoniaceae): differences between regions with different pollinators and herbivores Am. J. Botany, August 1, 2002; 89(8): 1260 - 1269. [Abstract] [Full Text] [PDF]

				C. J. Murren, N. Pendleton, and M. Pigliucci Evolution of phenotypic integration in Brassica (Brassicaceae) Am. J. Botany, April 1, 2002; 89(4): 655 - 663. [Abstract] [Full Text] [PDF]