Clowers Katie J, Lyman Richard F, Mackay Trudy F C, Morgan Theodore J
The Division of Biology and The Ecological Genomics Institute, Kansas State University, Manhattan, KS 66506, USA.
Genet Res (Camb). 2010 Apr;92(2):103-13. doi: 10.1017/S0016672310000108.
A comprehensive understanding of the genetic basis of phenotypic adaptation in nature requires the identification of the functional allelic variation underlying adaptive phenotypes. The manner in which organisms respond to temperature extremes is an adaptation in many species. In the current study, we investigate the role of molecular variation in senescence marker protein-30 (Smp-30) on natural phenotypic variation in cold tolerance in Drosophila melanogaster. Smp-30 encodes a product that is thought to be involved in the regulation of Ca2+ ion homeostasis and has been shown previously to be differentially expressed in response to cold stress. Thus, we sought to assess whether molecular variation in Smp-30 was associated with natural phenotypic variation in cold tolerance in a panel of naturally derived inbred lines from a population in Raleigh, North Carolina. We identified four non-coding polymorphisms that were strongly associated with natural phenotypic variation in cold tolerance. Interestingly, two polymorphisms that were in close proximity to one another (2 bp apart) exhibited opposite phenotypic effects. Consistent with the maintenance of a pair of antagonistically acting polymorphisms, tests of molecular evolution identified a significant excess of maintained variation in this region, suggesting balancing selection is acting to maintain this variation. These results suggest that multiple mutations in non-coding regions can have significant effects on phenotypic variation in adaptive traits within natural populations, and that balancing selection can maintain polymorphisms with opposite effects on phenotypic variation.
全面了解自然界中表型适应的遗传基础，需要确定适应性表型背后的功能性等位基因变异。生物对极端温度的反应方式是许多物种的一种适应。在本研究中，我们调查了衰老标记蛋白30（Smp-30）中的分子变异对黑腹果蝇耐寒性自然表型变异的作用。Smp-30编码一种被认为参与钙离子稳态调节的产物，并且先前已证明其在冷应激反应中差异表达。因此，我们试图评估Smp-30中的分子变异是否与来自北卡罗来纳州罗利市一个种群的一组自然衍生近交系中耐寒性的自然表型变异相关。我们鉴定出四个与耐寒性自然表型变异密切相关的非编码多态性。有趣的是，两个彼此紧邻（相隔2个碱基对）的多态性表现出相反的表型效应。与一对拮抗作用多态性的维持一致，分子进化测试在该区域发现了显著过量的维持变异，表明平衡选择正在起作用以维持这种变异。这些结果表明，非编码区域的多个突变可对自然种群中适应性状的表型变异产生重大影响，并且平衡选择可维持对表型变异具有相反效应的多态性。
