Behera Narayan, Nanjundiah Vidyanand
Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560004, India.
J Theor Biol. 2004 Jan 21;226(2):177-84. doi: 10.1016/j.jtbi.2003.08.011.
Using a computational model of string-like haploid genotypes, we verify the conjecture (J. Theor. Biol. 188 (1997) 153) that phenotypic plasticity can speed up evolution. The corresponding real-life situation was realized by Waddington in experiments carried out on the fruit fly Drosophila. Waddington found that after selecting for an environmentally induced trait over a number of generations, a new, true-breeding phenotype resulted that was absent in the starting population. The phenomenon, termed 'genetic assimilation', continues to attract interest because of the rapidity of the effect and because of its seemingly Lamarckian implications. By making use of a genetic algorithm-based approach developed previously, we show that conventional Darwinian selection acting on regulatory genes can account for genetic assimilation. The essential assumption in our model is that a structural gene can be in either of three allelic states. These correspond to its being (a) 'on' or 'off' constitutively or (b) in a plastic state in which the probability that it is 'on' or 'off' is influenced by regulatory loci in a dosage-dependent manner.
利用类串单倍体基因型的计算模型，我们验证了一个猜想（《理论生物学杂志》188 (1997) 153），即表型可塑性能够加速进化。相应的现实情况由沃丁顿在对果蝇进行的实验中实现。沃丁顿发现，在多代选择一种环境诱导性状后，产生了一种新的、能真实遗传的表型，而该表型在起始种群中并不存在。这种被称为“遗传同化”的现象，因其效应的快速性及其看似拉马克式的含义，一直吸引着人们的关注。通过利用先前开发的基于遗传算法的方法，我们表明作用于调控基因的传统达尔文选择能够解释遗传同化现象。我们模型中的基本假设是，一个结构基因可以处于三种等位基因状态中的任何一种。这三种状态分别对应于它（a）组成型地“开启”或“关闭”，或者（b）处于一种可塑性状态，即其“开启”或“关闭”的概率受到调控位点的剂量依赖性影响。
