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The Adaptive Significance of Sexual Lability in Plants Using Atriplex canescens as a Principal Example

D. C. Freeman, E. D. McArthur and K. T. Harper
Annals of the Missouri Botanical Garden
Vol. 71, No. 1 (1984), pp. 265-277
DOI: 10.2307/2399070
Stable URL: http://www.jstor.org/stable/2399070
Page Count: 13
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The Adaptive Significance of Sexual Lability in Plants Using Atriplex canescens as a Principal Example
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Abstract

Experimental studies demonstrate that up to 20% of the individuals of Atriplex canescens and other species of the genus can alter their sexual state from one season to the next. Approximately 5% of the A. canescens individuals changed from an exclusively pistillate phenotype to an exclusively staminate phenotype or vice versa. Another 5% of the individuals changed their primary sexual emphasis, e.g., from an exclusively pistillate condition to a dominantly staminate, monoecious condition. In addition, 10% of the population changed from a unisexual state to a monoecious state in which staminate and pistillate flowers were approximately equal in number (or vice versa). In Atriplex canescens, sex change occurred in response to three stresses: an unusually cold winter, drought, and prior heavy seed set. When placed under stress, pistillate individuals are significantly more likely to change sex than staminate individuals. The ability to change sex appears to confer a survival advantage to the individual. Plants which change sex also appear to begin reproducing earlier than pistillate plants while producing as many seeds as pistillate plants do. Thus individuals that change sex appear to have some reproductive advantages in the population studied.

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