Loukas M, Krimbas C B, Vergini Y
Genetics. 1979 Oct;93(2):497-523. doi: 10.1093/genetics/93.2.497.
Gametic frequencies were obtained in four natural populations of D. sub-obscura by extracting wild chromosomes and subsequently analyzing them for inversions and allozymes. The genes Lap and Pept-1, both located within the same inversions of chromosome O, were found in striking nonrandom associations with them of the same kind and degree in all populations studied. On the contrary, the gene Acph, also located within the previously mentioned inversions, was found in linkage disequilibrium with them only in two populations and of opposite directions. This is also the case for the genes Est-9 and Hk, both located within chromosome E inversions. While the gene Est-9 was in strong linkage disequilibrium with the inversions, of the same kind and degree in all populations studied, Hk was found to be in linkage equilibrium. Allele frequencies for the 29 genes studied do not show geographical variation except for the genes Lap, Pept-1 and Est-9, the ones found in linkage disequilibria with the geographically varying gene arrangements. Although mechanical or historical explanations for these equilibria cannot be ruled out, these data cannot be explained satisfactorily by the "middle gene explanation," which states that loci displaying such linkage disequilibria are the ones located near the break points of inversions, while the ones displaying linkage equilibria with them are located in the middle of them. There is no evidence for consistent linkage disequilibria between pairs of loci, except for the closely linked genes of the complex locus, Est-9. This would imply, if it is not a peculiarity of the Est-9 complex, that the linkage disequilibria are found only between very closely linked loci or that, for less closely linked genes, the associations are too weak to be detected by the usual samples sizes.
通过提取野生染色体并随后分析其倒位和等位酶，在四个暗果蝇自然种群中获得了配子频率。位于O染色体相同倒位内的Lap和Pept - 1基因，在所有研究种群中均与相同类型和程度的倒位呈现出显著的非随机关联。相反，同样位于上述倒位内的Acph基因，仅在两个种群中与倒位处于连锁不平衡状态，且方向相反。位于E染色体倒位内的Est - 9和Hk基因也是如此。虽然Est - 9基因在所有研究种群中均与倒位处于强烈的连锁不平衡状态，且类型和程度相同，但Hk基因处于连锁平衡状态。除了Lap、Pept - 1和Est - 9基因外，所研究的29个基因的等位基因频率未表现出地理变异，这三个基因与地理上变化的基因排列处于连锁不平衡状态。尽管不能排除对这些平衡的机械或历史解释，但这些数据无法用“中间基因解释”得到令人满意的解释，该解释认为显示这种连锁不平衡的基因座是位于倒位断点附近的基因座，而与它们显示连锁平衡的基因座位于倒位中间。除了紧密连锁的Est - 9复合基因座的基因外，没有证据表明基因座对之间存在一致的连锁不平衡。如果这不是Est - 9复合体的特性，这将意味着连锁不平衡仅在非常紧密连锁的基因座之间发现，或者对于连锁不那么紧密的基因，这种关联太弱以至于无法通过通常的样本量检测到。
