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Title:
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Insect seed predators as novel agents of selection on fruit color |
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Author:
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Stanton, Maureen L; Whitney, Kenneth D
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Abstract:
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The ecological and evolutionary dynamics of fruit color polymorphisms
remain poorly known because patterns and agents of selection have rarely been identified.
Here, we examine Acacia ligulata, a shrub of the Australian arid zone characterized by a
red/yellow/orange aril color polymorphism. Seed production patterns over four populations
and three years suggested that spatially variable selection may be acting to maintain the
polymorphism: red and yellow aril color morphs each had the highest seed production in
alternate sites. Seed production differences between morphs were a function of both intrinsic
plant characters (fruit production) and predispersal seed predation, which affects the number
of viable seeds matured per ovule. Fruit production differences are hypothesized to result
from a genotype-by-environment interaction, perhaps related to plant vigor. In contrast,
morph differences in the numbers of viable seeds per ovule are produced via differential
seed predation by heteropteran insects, as demonstrated by exclusion experiments. Because
these predators feed when aril color is not visible, differential predation is evidently a
response to pleiotropic effects of fruit color alleles. We suggest that such pleiotropic effects
may be a common feature of fruit color polymorphisms, and that the most obvious selective
agents (that is, seed dispersers) may not always be the most important. |
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Description:
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Copyright by the Ecological Society of America |
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Citation:
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Whitney, K. D., and M. L. Stanton. 2004. Insect seed predators as novel agents of selection on fruit color. Ecology 85: 2153-2160 |
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Citable link to this page:
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http://hdl.handle.net/1911/21690 |
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Date:
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2004-08 |
