von Sternberg Richard
Department of Systematic Biology, NHB-163, National Museum of Natural History, Smithsonian Institution, Washington, DC 20560, USA.
Ann N Y Acad Sci. 2002 Dec;981:154-88. doi: 10.1111/j.1749-6632.2002.tb04917.x.
Repetitive DNA sequences comprise a substantial portion of most eukaryotic and some prokaryotic chromosomes. Despite nearly forty years of research, the functions of various sequence families as a whole and their monomer units remain largely unknown. The inability to map specific functional roles onto many repetitive DNA elements (REs), coupled with the taxon-specificity of sequence families, have led many to speculate that these genomic components are "selfish" replicators generating genomic "junk." The purpose of this paper is to critically examine the selfishness, evolutionary effects, and functionality of REs. First, a brief overview of the range of ideas pertaining to RE function is presented. Second, the argument is presented that the selfish DNA "hypothesis" is actually a narrative scheme, that it serves to protect neo-Darwinian assumptions from criticism, and that this story is untestable and therefore not a hypothesis. Third, attempts to synthesize the selfish DNA concept with complex systems models of the genome and RE functionality are critiqued. Fourth, the supposed connection between RE-induced mutations and macroevolutionary events are stated to be at variance with empirical evidence and theoretical considerations. Hypotheses that base phylogenetic transitions in repetitive sequence changes thus remain speculative. Fifth and finally, the case is made for viewing REs as integrally functional components of chromosomes, genomes, and cells. It is argued throughout that a new conceptual framework is needed for understanding the roles of repetitive DNA in genomic/epigenetic systems, and that neo-Darwinian "narratives" have been the primary obstacle to elucidating the effects of these enigmatic components of chromosomes.
重复DNA序列构成了大多数真核生物和一些原核生物染色体的很大一部分。尽管经过了近四十年的研究，但各种序列家族作为一个整体及其单体单元的功能在很大程度上仍然未知。由于无法将特定的功能作用映射到许多重复DNA元件（REs）上，再加上序列家族的分类群特异性，许多人推测这些基因组成分是产生基因组“垃圾”的“自私”复制子。本文的目的是批判性地审视REs的自私性、进化效应和功能。首先，简要概述了与RE功能相关的一系列观点。其次，提出论点认为，自私DNA“假说”实际上是一种叙事模式，它用于保护新达尔文主义假设免受批评，而且这个故事无法验证，因此不是一个假说。第三，对将自私DNA概念与基因组和RE功能的复杂系统模型进行综合的尝试进行了批判。第四，指出RE诱导的突变与宏观进化事件之间的所谓联系与经验证据和理论考量不一致。因此，基于重复序列变化进行系统发育转变的假说仍然具有推测性。第五也是最后一点，提出将REs视为染色体、基因组和细胞不可或缺的功能组成部分的观点。本文始终认为，需要一个新的概念框架来理解重复DNA在基因组/表观遗传系统中的作用，而且新达尔文主义“叙事”一直是阐明染色体这些神秘成分作用的主要障碍。
