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

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...

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Bibliographic Details
Published in:American journal of botany 2007-06, Vol.94 (6), p.972
Main Authors: Weller, Stephen G, Domínguez, César A, Molina-Freaner, Francisco E, noni, Juan, LeBuhn, Gretchen
Format: Article
Language:English
Subjects:
Botany
Flowers & plants
Inbreeding
Plant populations
Plant reproduction
Online Access:Get full text
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Summary: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. [PUBLICATION ABSTRACT]
ISSN:0002-9122
1537-2197