Modularity and Intrinsic Evolvability of Hsp90-Buffered Change
Modularity and Intrinsic Evolvability of Hsp90-Buffered Change
复制标题
DOI：
10.1371/journal.pone.0000076
复制
发表时间：
2006-12-20
期刊：
影响因子：
3.7
通讯作者：
Rutherford, Suzannah
中科院分区：
文献类型：
--
作者：
Carey, Charles C.;Gorman, Kristen F.;Rutherford, Suzannah
Hsp90在许多生物体的广泛形态特征中控制着戏剧性的表型转变。特定异常的遗传背景依赖性及其对实验室选择的反应表明，Hsp90可能是一个“进化电容器”，允许发育变异在正常条件下作为中性等位基因积累，并在环境胁迫下表现出可选择的形态差异。Hsp90缓冲变异与进化的相关性经常受到这样一种观点的挑战，即由Hsp90控制的大形态变化是无条件有害的。为了解决这个问题，我们测试了果蝇中hsp90缓冲异常的非选择多效效应和相关的适应度成本。在六个高度相关的选择系中，高达120倍的外显率差异，从最初的少数果蝇开始，并迅速选择支持或反对变形的眼睛特征（dfe），并没有转化为在生存能力，寿命或竞争适应性的几项测试中的任何可测量的差异。在1400多个重组品系中，也没有17个不同的QTL与适应度效应相关。我们能够检测到可测量的近交、媒介环境和选择系背景中的白色突变的独立于不同外显率的影响，这表明，在实验室适合度测试的限制下，这种由Hsp90控制的大形态变化是可选择的，独立于强的、相关的和无条件的有害影响。Hsp90隐藏的多基因变异使得潜在的有害等位基因在选择过程中很容易被具有相似表型效应的危害性较小的等位基因所取代。Hsp90将环境胁迫与控制前所未有的形态可塑性的发育变异表达联系起来。正如本文和本期论文中概述的那样，Hsp90缓冲变异的复杂遗传结构支持了Hsp90对定量和定性表型影响的显著模块化，这与“Hsp90电容器假说”和阈值性状的标准定量遗传模型一致。
Hsp90 controls dramatic phenotypic transitions in a wide array of morphological features of many organisms. The genetic-background dependence of specific abnormalities and their response to laboratory selection suggested Hsp90 could be an 'evolutionary capacitor', allowing developmental variation to accumulate as neutral alleles under normal conditions and manifest selectable morphological differences during environmental stress. The relevance of Hsp90-buffered variation for evolution has been most often challenged by the idea that large morphological changes controlled by Hsp90 are unconditionally deleterious. To address this issue, we tested an Hsp90-buffered abnormality in Drosophila for unselected pleiotropic effects and correlated fitness costs. Up to 120-fold differences in penetrance among six highly related selection lines, started from an initially small number of flies and rapidly selected for and against a deformed eye trait (dfe), did not translate into measurable differences in any of several tests of viability, lifespan or competitive fitness. Nor were 17 dfe Quantitative Trait Loci (QTL) associated with fitness effects in over 1,400 recombinant lines. Our ability to detect measurable effects of inbreeding, media environment and the white mutation in the selection line backgrounds independent of dfe penetrance suggests that, within the limitations of laboratory tests of fitness, this large morphological change controlled by Hsp90 was selectable independent of strong, correlated and unconditionally deleterious effects-abundant, polygenic variation hidden by Hsp90 allows potentially deleterious alleles to be readily replaced during selection by less deleterious alleles with similar phenotypic effects. Hsp90 links environmental stress with the expression of developmental variation controlling unprecedented morphological plasticity. As outlined here and in the companion paper of this issue, the complex genetic architecture of Hsp90-buffered variation supports a remarkable modularity of Hsp90 effects on quantitative and qualitative phenotypes, consistent with the 'Hsp90 capacitor hypothesis' and standard quantitative genetic models of threshold traits.