Does evolutionary plasticity evolve?
Does evolutionary plasticity evolve?
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DOI：
10.1111/j.1558-5646.1996.tb02342.x
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发表时间：
1996-06-01
期刊：
影响因子：
3.3
通讯作者：
Wagner, A
中科院分区：
文献类型：
--
作者：
Wagner, A
在从受精卵发育为多细胞生物体的过程中，在亚生物体组织的各个层面都发生大量的表观遗传相互作用。这就增加了一种可能性，即表观遗传相互作用系统可能补偿或“缓冲”其最低层面上作为突变而发生的一些变化，从而使表型相对于突变保持稳定。这种假设的现象将被称为“表观遗传稳定性”。其潜在重要性源于这样一个事实，即具有遗传基础的表型变异是进化的必要前提。因此，表观遗传稳定性的差异可能深刻影响可达到的进化速率。虽然表观遗传稳定性代表一种发育系统的系统特性，但它自身可能由基因决定，因而会受到进化改变的影响。理想情况下，是否如此应该直接通过实验来回答。所涉及的时间尺度以及我们对发育途径定量理解的不足，可能在可预见的未来排除这种方法。这里通过使用一个基于生物化学的发育途径中一个小但核心部分的模型来寻求初步答案。所模拟的是一组转录调节因子，它们相互调节彼此的表达，从而形成稳定的基因表达模式。这种对决定发育模式形成事件至关重要的基因表达模式，很可能受到强烈的稳定化自然选择。经过长时间的稳定选择，在模型中导致基因表达模式改变的突变比例大幅降低。表观遗传稳定性提高了。这种现象在转录因子基因之间差异很大的调节情形中都能发现。讨论认为只有上位性（非线性）基因相互作用才能导致表观遗传稳定性的这种变化。讨论了来自古生物学、分子进化、发育和遗传学的与表观遗传稳定性存在差异相符的证据。概述了表观遗传稳定性与发育限渠道化的关系。提出了可能提供进一步证据的实验方案。
During the development of a multicellular organism from a zygote, a large number of epigenetic interactions take place on every level of suborganismal organization. This raises the possibility that the system of epigenetic interactions may compensate or ''buffer'' some of the changes that occur as mutations on its lowest levels, and thus stabilize the phenotype with respect to mutations. This hypothetical phenomenon will be called ''epigenetic stability.'' Its potential importance stems from the fact that phenotypic variation with a genetic basis is an essential prerequisite for evolution. Thus, variation in epigenetic stability might profoundly affect attainable rates of evolution. While representing a systemic property of a developmental system, epigenetic stability might itself be genetically determined and thus be subject to evolutionary change, Whether or not this is the case should ideally be answered directly, that is, by experimentation. The time seals involved and our insufficient quantitative understanding of developmental pathways will probably preclude such an approach in the foreseeable future. Preliminary answers are sought here by using a biochemically motivated model of a small bur central part of a developmental pathway. Modeled are sets of transcriptional regulators that mutually regulate each other's expression and thereby form stable gene expression patterns. Such gene-expression patterns, crucially involved in determining developmental pattern formation events, are most likely subject to strong stabilizing natural selection, After long periods of stabilizing selection. the fraction of mutations causing changes in gene-expression pattern is substantially reduced in the model. Epigenetic stability has increased. This phenomenon is found for widely varying regulatory scenarios among transcription factor genes. Its discussed that only epistatic (nonlinear) gene interactions can cause such change in epigenetic stability. Evidence from paleontology, molecular evolution, development, and genetics, consistent with the existence of variation in epigenetic stability, is discussed, The relation of epigenetic stability to developmental canalization is outlined. Experimental scenarios at suggested thar may provide further evidence.