Quantitative Genetics of Bryozoan Phenotypic Evolution. III. Phenotypic Plasticity and the Maintenance of Genetic Variation

Cheilostome bryozoan species show long-term morphologic stasis, implying stabilizing selection sustained for millions of years, but nevertheless retain significant heritable variation in traits of skeletal morphology The possible role of within-genotype (within-colony) phenotypic variability in pres...

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Bibliographic Details
Published in:Evolution 1995-04, Vol.49 (2), p.290-296
Main Authors: Cheetham, Alan H., Jeremy B. C. Jackson, Hayek, Lee-Ann C.
Format: Article
Language:English
Subjects:
Aquatic life
Bryozoa
Evolution
Evolutionary genetics
Genetic variation
Genetics
genotype‐environment interaction
Heritability
Mutation
Phenotypic plasticity
Phenotypic traits
phenotypic variance
Population genetics
Quantitative genetics
skeletal morphology
Statistical discrepancies
Statistical variance
Stylopoma
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Summary:Cheilostome bryozoan species show long-term morphologic stasis, implying stabilizing selection sustained for millions of years, but nevertheless retain significant heritable variation in traits of skeletal morphology The possible role of within-genotype (within-colony) phenotypic variability in preserving genetic diversity was analyzed using breeding data for two species of Stylopoma from sites along 110 km of the Caribbean coast of Panama. Variation among zooids within colonies accounts for nearly two-thirds of the phenotypic variance on average, increases with environmental heterogeneity, and includes significant genotype-environment interaction. Thus, within-colony variability apparently represents phenotypic plasticity, at least some of which is heritable, rather than random "developmental noise." Almost all of the among-colonies component of phenotypic variance is accounted for by additive genetic differences in trait means, suggesting that within-colony plasticity includes virtually all of the environmental component of phenotypic variance in these populations of Stylopoma. Thus, heritable within-colony plasticity could play a significant part in maintaining genetic diversity in cheilostomes, but it is also possible that rates of polygenic mutation alone are sufficient to balance the effects of selection.
ISSN:0014-3820
1558-5646
DOI:10.1111/j.1558-5646.1995.tb02241.x