Czelusniak J, Goodman M, Hewett-Emmett D, Weiss M L, Venta P J, Tashian R E
Nature. 1982 Jul 15;298(5871):297-300. doi: 10.1038/298297a0.
Recent years have seen rapid growth in amino acid sequence data on globins and nucleotide sequence data on haemoglobin genes and pseudogenes, and cladistic analysis of these data continues to reveal new facets of globin evolution. Our present findings demonstrate: (1) avian and mammalian embryonic alpha genes (pi and xi, respectively) had a monophyletic origin involving an alpha locus duplication about 400 Myr ago soon after the duplication which separated alpha and beta genes; (2) much later in phylogeny, independent beta-gene duplications produced the embryonic rho locus of birds and embryonic epsilon and fetal gamma loci of mammals. This parallels the earlier finding that myoglobins evolved more than once from generalized globin ancestors. Here we support the view that such globin evolution resulted from natural selection acting on mutations in duplicated genes. Thus, our evidence contradicts the neutralist view in which almost all amino acid substitutions in descent to extant globins evaded positive selection.
近年来，关于珠蛋白的氨基酸序列数据以及血红蛋白基因和假基因的核苷酸序列数据迅速增长，对这些数据的分支系统发育分析不断揭示珠蛋白进化的新情况。我们目前的研究结果表明：（1）鸟类和哺乳动物的胚胎α基因（分别为π和ξ）有一个单系起源，涉及约4亿年前在α和β基因分离后的一次α基因座复制；（2）在系统发育的后期，独立的β基因复制产生了鸟类的胚胎ρ基因座以及哺乳动物的胚胎ε和胎儿γ基因座。这与早期发现的肌红蛋白从广义的珠蛋白祖先多次进化的情况相似。在这里，我们支持这样一种观点，即这种珠蛋白进化是由对复制基因中的突变进行自然选择导致的。因此，我们的证据与中性论观点相矛盾，在中性论观点中，在现存珠蛋白的演化过程中几乎所有的氨基酸替换都逃避了正选择。
