Evidence of adaptive divergence in plasticity: Density- and site-dependent selection on shade-avoidance responses in Impatiens capensis

Department of Ecology and Evolutionary Biology, Brown University, Providence, Rhode Island 02912, USA.
Evolution (Impact Factor: 4.61). 01/2001; 54(6):1956-68. DOI: 10.1554/0014-3820(2000)054[1956:EOADIP]2.0.CO;2
Source: PubMed


We investigated the conditions under which plastic responses to density are adaptive in natural populations of Impatiens capensis and determined whether plasticity has evolved differently in different selective environments. Previous studies showed that a population that evolved in a sunny site exhibited greater plasticity in response to density than did a population that evolved in a woodland site. Using replicate inbred lines in a reciprocal transplant that included a density manipulation, we asked whether such population differentiation was consistent with the hypothesis of adaptive divergence. We hypothesized that plasticity would be more strongly favored in the sunny site than in the woodland site; consequently, we predicted that selection would be more strongly density dependent in the sunny site, favoring the phenotype that was expressed at each density. Selection on internode length and flowering date was consistent with the hypothesis of adaptive divergence in plasticity. Few costs or benefits of plasticity were detected independently from the expressed phenotype, so plasticity was selected primarily through selection on the phenotype. Correlations between phenotypes and their plasticity varied with the environment and would cause indirect selection on plasticity to be environment dependent. We showed that an appropriate plastic response even to a rare environment can greatly increase genotypic fitness when that environment is favorable. Selection on the measured characters contributed to local adaptation and fully accounted for fitness differences between populations in all treatments except the woodland site at natural density.

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Available from: Kathleen Donohue, Apr 01, 2014
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    • "Indeed, there is some evidence that changes in competitive regimes can affect selection on plant traits within populations. For example, in experiments measuring phenotypic selection on plants grown with and without competitors, altered competition with conspecifics (Donohue et al. 2000) and heterospecifics (Weinig 2000; Tiffin 2002; Lau 2008) can affect selection on plant traits. The direction of selection can also differ depending on whether plants are surrounded by conspecifics or heterospecifics (Lankau and Strauss 2007). "
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    • "studies of several plant species report that there is selection for plasticity in flowering time in 66 response to an increase in density (Thomas & Bazzaz, 1993; Donohue et al., 2000; Weinig et 67 al., 2006). Interestingly, these studies show that genotypes differ in the level and direction of 68 plastic responses to changing plant population density (i.e. "
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    • "Integrative and Comparative Biology, pp. 1–8 doi:10.1093/icb/icu078 Society for Integrative and Comparative Biology et al. 1998; Donohue et al. 2000; Lind et al. 2007; Hollander 2008; Baythavong 2011). Similar conditions are predicted to select for TGP (Uller 2008; Day and Bonduriansky 2011; Bonduriansky et al. 2012); TGP is predicted to be favored when (1) there is environmental heterogeneity across generations , (2) offspring's environmental conditions are predictable from parental environmental conditions, and (3) the costs of cue-induction are low for parents and offspring. "
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