Elder J F, Turner B J
Department of Biology, Virginia Polytechnic Institute and State University, Blacksburg 24061.
Proc Natl Acad Sci U S A. 1994 Feb 1;91(3):994-8. doi: 10.1073/pnas.91.3.994.
The canonical monomers (approximately 170 bp) of an abundant (1.9 x 10(6) copies per diploid genome) satellite DNA sequence family in the genome of Cyprinodon variegatus, a "pupfish" that ranges along the Atlantic coast from Cape Cod to central Mexico, are divergent in base sequence in 10 of 12 samples collected from natural populations. The divergence involves substitutions, deletions, and insertions, is marked in scope (mean pairwise sequence similarity = 61.6%; range = 35-95.9%), is largely confined to the 3' half of the monomer, and is not correlated with the distance among collecting sites. Repetitive cloning and direct genomic sequencing experiments failed to detect intrapopulation and intraindividual variation, suggesting high levels of sequence homogeneity within populations. The satellite sequence has therefore undergone "concerted evolution," at the level of the local population. Concerted evolution has previously almost always been discussed in terms of the divergence of species or higher taxa; its intraspecific occurrence apparently has not been reported previously. The generality of the observation is difficult to evaluate, for although satellite DNAs from a large number of organisms have been studied in detail, there appear to be little or no other data on their sequence variation in natural populations. The relationship (if any) between concerted, population level, satellite DNA divergence and the extent of gene flow/genetic isolation among conspecific natural populations remains to be established.
在一种“鳉鱼”——多氏鳉（Cyprinodon variegatus）的基因组中，有一个丰富的卫星DNA序列家族（每个二倍体基因组约有1.9×10⁶个拷贝），其典型单体（约170 bp）在从自然种群采集的12个样本中的10个样本里，碱基序列存在差异。这种差异涉及替换、缺失和插入，范围显著（平均成对序列相似性 = 61.6%；范围 = 35 - 95.9%），主要局限于单体的3' 端，且与采集地点之间的距离无关。重复克隆和直接基因组测序实验未能检测到种群内和个体内的变异，这表明种群内序列具有高度同质性。因此，该卫星序列在当地种群水平上经历了“协同进化”。协同进化此前几乎总是从物种或更高分类群的差异角度进行讨论；其在种内的发生此前显然尚未有报道。由于尽管已经对大量生物体的卫星DNA进行了详细研究，但似乎几乎没有关于其自然种群中序列变异的其他数据，所以很难评估这一观察结果的普遍性。种内自然种群中协同的、种群水平的卫星DNA差异与基因流/遗传隔离程度之间的关系（如果有的话）仍有待确定。
