Multilevel Selection Theory and the Evolutionary Functions of Transposable Elements
Multilevel Selection Theory and the Evolutionary Functions of Transposable Elements
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DOI：
10.1093/gbe/evv152
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发表时间：
2015-08-01
影响因子：
3.3
通讯作者：
Doolittle, W. Ford
中科院分区：
文献类型：
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作者：
Brunet, Tyler D. P.;Doolittle, W. Ford
关于“垃圾DNA”的新争论中的几个问题之一是组织水平，在该水平上基因组特征可能被视为被选择，从而展现出病因学定义的功能。分子遗传学家经常表达的直觉是，垃圾DNA之所以具有功能，是因为它可以“加速进化”或作为“进化库”，可以被重新解读为关于物种（或进化枝）之间而不是物种内部选择的主张，但这种情况并不常见。在这里，我们回顾了关于在进化中高于生物体的水平上进行选择的重要性的一般论据，并进一步发展了它们的共同基因组特征：转座元件（TE）的携带。在许多物种中，尤其是我们自己的物种中，TE 占所有核 DNA 的很大一部分，而它们是否单独或集体有助于健康（或者相反）是一个持续争论的话题。即使TE通常归因于最低水平（基因组）的自私选择，它们在现存生物体中的普遍性以及携带它们的现存生物体的普遍性也必须对物种内（关于生物体适应性）和物种间（关于物种形成和灭绝率）的选择做出反应。在更高的水平上，进化枝的持久性可能会受到 TE 携带的影响（正面或负面）。如果 TE 确实加速了进化，那么正是在这些更高层次的选择中，这种功能最好归因于它们作为一个类别。
One of several issues at play in the renewed debate over "junk DNA" is the organizational level at which genomic features might be seen as selected, and thus to exhibit function, as etiologically defined. The intuition frequently expressed by molecular geneticists that junk DNA is functional because it serves to "speed evolution" or as an "evolutionary repository" could be recast as a claim about selection between species (or clades) rather than within them, but this is not often done. Here, we review general arguments for the importance of selection at levels above that of organisms in evolution, and develop them further for a common genomic feature: the carriage of transposable elements (TEs). In many species, not least our own, TEs comprise a large fraction of all nuclear DNA, and whether they individually or collectively contribute to fitness-or are instead junk-is a subject of ongoing contestation. Even if TEs generally owe their origin to selfish selection at the lowest level (that of genomes), their prevalence in extant organisms and the prevalence of extant organisms bearing them must also respond to selection within species (on organismal fitness) and between species (on rates of speciation and extinction). At an even higher level, the persistence of clades may be affected (positively or negatively) by TE carriage. If indeed TEs speed evolution, it is at these higher levels of selection that such a function might best be attributed to them as a class.