Gerrish Philip J, Colato Alexandre, Perelson Alan S, Sniegowski Paul D
Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, NM 87501, USA.
Proc Natl Acad Sci U S A. 2007 Apr 10;104(15):6266-71. doi: 10.1073/pnas.0607280104. Epub 2007 Apr 3.
The intricate adjustment of organisms to their environment demonstrates the effectiveness of natural selection. But Darwin himself recognized that certain biological features could limit this effectiveness, features that generally reduce the efficiency of natural selection or yield suboptimal adaptation. Genetic linkage is known to be one such feature, and here we show theoretically that it can introduce a more sinister flaw: when there is complete linkage between loci affecting fitness and loci affecting mutation rate, positive natural selection and recurrent mutation can drive mutation rates in an adapting population to intolerable levels. We discuss potential implications of this finding for the early establishment of recombination, the evolutionary fate of asexual populations, and immunological clearance of clonal pathogens.
生物体对其环境的复杂调节体现了自然选择的有效性。但达尔文本人也认识到某些生物学特征可能会限制这种有效性，这些特征通常会降低自然选择的效率或导致适应性次优。基因连锁就是这样一种特征，在此我们从理论上表明它可能会引入一个更严重的缺陷：当影响适合度的基因座与影响突变率的基因座完全连锁时，正向自然选择和反复突变会使适应种群中的突变率升至无法容忍的水平。我们讨论了这一发现对于重组的早期建立、无性种群的进化命运以及克隆病原体的免疫清除的潜在影响。
