Bickel Ryan D, Schackwitz Wendy S, Pennacchio Len A, Nuzhdin Sergey V, Kopp Artyom
Department of Biological Sciences, University of Southern California, Los Angeles, 90089, USA.
J Mol Evol. 2009 Aug;69(2):194-202. doi: 10.1007/s00239-009-9265-y. Epub 2009 Jul 29.
Genes with overlapping expression and function may gradually diverge despite retaining some common functions. To test whether such genes show distinct patterns of molecular evolution within species, we examined sequence variation at the bric à brac (bab) locus of Drosophila melanogaster. This locus is composed of two anciently duplicated paralogs, bab1 and bab2, which are involved in patterning the adult abdomen, legs, and ovaries. We have sequenced the 148 kb genomic region spanning the bab1 and bab2 genes from 94 inbred lines of D. melanogaster sampled from a single location. Two non-coding regions, one in each paralog, appear to be under selection. The strongest evidence of directional selection is found in a region of bab2 that has no known functional role. The other region is located in the bab1 paralog and is known to contain a cis-regulatory element that controls sex-specific abdominal pigmentation. The coding region of bab1 appears to be under stronger functional constraint than the bab2 coding sequences. Thus, the two paralogs are evolving under different selective regimes in the same natural population, illuminating the different evolutionary trajectories of partially redundant duplicate genes.
具有重叠表达和功能的基因尽管保留了一些共同功能，但可能会逐渐分化。为了测试这类基因在物种内是否呈现出独特的分子进化模式，我们研究了黑腹果蝇的bric à brac（bab）基因座处的序列变异。该基因座由两个古老的重复旁系同源基因bab1和bab2组成，它们参与成虫腹部、腿部和卵巢的模式形成。我们对从单一地点采集的94个黑腹果蝇近交系中跨越bab1和bab2基因的148 kb基因组区域进行了测序。两个非编码区域，每个旁系同源基因各一个，似乎受到了选择。定向选择的最有力证据出现在bab2的一个没有已知功能作用的区域。另一个区域位于bab1旁系同源基因中，已知包含一个控制性别特异性腹部色素沉着的顺式调控元件。bab1的编码区域似乎比bab2的编码序列受到更强的功能限制。因此，这两个旁系同源基因在同一自然种群中处于不同的选择机制下进化，揭示了部分冗余重复基因的不同进化轨迹。
