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 (1) Citing Articles via Google Scholar Google Scholar Articles by Weller, S. G. Articles by LeBuhn, G. Search for Related Content PubMed Articles by Weller, S. G. Articles by LeBuhn, G. Agricola Articles by Weller, S. G. Articles by LeBuhn, G.

The evolution of distyly from tristyly in populations of Oxalis alpina (Oxalidaceae) in the Sky Islands of the Sonoran Desert¹

Department of Ecology and Evolutionary Biology, University of California, Irvine, California 92697 USA; Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Apartado Postal 70-275, C.P. 04510, México Distrito Federal, México; Departamento de Ecología de la Biodiversidad, Estación Regional del Noroeste, Instituto de Ecología, Universidad Nacional Autónoma de México, Apartado Postal 1354, C.P. 83000, Hermosillo, Sonora, México; Department of Biology, San Francisco State University, 1600 Holloway Avenue, San Francisco, California 94132 USA

ABSTRACT

The evolution of distyly from tristyly was investigated in populations of Oxalis alpina at high elevations throughout the Sky Islands of the Sonoran Desert. Incompatibility systems in tristylous populations, where self-incompatible short-, mid-, and long-styled morphs occur in populations, vary from those typical of tristylous species in which each morph is equally capable of fertilizing ovules of the other two morphs, to breeding systems in which incompatibility relationships are asymmetric. In these populations, selection against the allele controlling expression of the mid-styled morph is likely. The degree of modification of incompatibility in the short- and long-styled morphs in 10 populations was strongly associated with fewer mid-styled morphs, supporting models predicting the effect of these modifications of incompatibility on frequency of the mid-styled morph. Self-compatibility of the mid-styled morph may be important for maintaining the frequency of this morph, depending on the level of self-pollination, self-fertilization, and the extent of inbreeding depression. Modifications of incompatibility in tristylous populations and the distribution of distylous populations of O. alpina in the Sky Island region have similar geographic components, indicating the potential importance of historical factors in the evolution of distyly from tristyly.

Key Words: distyly • heterostyly • illegitimate crosses • legitimate crosses • Oxalis alpina • self-incompatibility • Sky Islands • tristyly

This article has been cited by other articles:

				K. A. Hodgins and S. C. H. Barrett Geographic variation in floral morphology and style-morph ratios in a sexually polymorphic daffodil Am. J. Botany, February 1, 2008; 95(2): 185 - 195. [Abstract] [Full Text] [PDF]