Epistasis: its role in complex tratis, gene expression and speciation

项目摘要 我们的目标是利用理论模型，基因表达阵列，分子遗传标记 (SNPs和微卫星）和分子进化理论，以更好地了解如何 基因相互作用（上位性）产生复杂的表型。作为我们的实验系统， 我们将使用最近收集的红粉甲虫，赤拟谷盗， 它们以种群间的形式表现出早期物种形成的特征， 行为受损、形态畸形和生育力降低的杂种， 生存能力我们的具体目标包括：（1）确认一对 来自不同种群的基因，当 在共同的遗传背景下聚集在一起;（2）表征分子 这些基因通过其表达模式和序列多样性的进化 在物种内和物种之间;（3）识别，确认和表征不同的集合 相互作用的基因，损害运动行为的种群间杂种;（4） 表征种群间杂交种之间的基因表达差异， 他们的父母使用Nimblegen（c）微阵列;和，（5）扩展和测试两个位点 种群遗传学理论的一个新的模型的物种形成的基础上相互作用， 一对基因，一个具有母性表达，一个具有合子表达。我们广泛 初步研究，来自北美和南美，非洲 和亚洲，揭示了显性，上位性，母体遗传效应， 基因型与环境相互作用导致形态和行为异常 降低了种群间杂交后代的生存能力和繁殖力。在最极端的情况下 混合健身减少，我们已经表明，通过反复回交到 基因组菌株GA-2和微卫星标记定位，表明一对特定的基因 相互作用以降低混合适应性。我们还表明，种群间的行为 在不同的一对种群之间的交配和回交中出现异常; 它们不是导致杂交种极度减少的基因之一， 适应性（上文）;它们涉及连锁基因组合的分解。通过 继续与基因组菌株的回交，我们可以分离出基因组合， 在共同的遗传背景下导致行为异常，证实了他们的 功能的身份，并表征其内部和物种之间的进化。

PROJECT SUMMARY Our goal is to use theoretical models, gene expression arrays, molecular genetic markers (SNPs and microsatellites) and molecular evolutionary theory to better understand how gene interactions (epistasis) produce complex phenotypes. As our experimental system, we will use recently collected populations of the red flour beetle, Tribolium castaneum, which exhibit characteristics of incipient speciation in the form of inter-population hybrids with impaired behavior, morphological deformities, and reduced fertility and viability. Our specific aims include (1) confirming the functional identity of a pair of genes from different populations that cause a total reduction of hybrid fitness when brought together in a common genetic background; (2) characterizing the molecular evolution of these genes through their patterns of expression and sequence diversity within and among species; (3) identifying, confirming and characterizing a different set of interacting genes which impair the motor behavior of inter-population hybrids; (4) characterizing the differences in gene expression between inter-population hybrids and their parents using Nimblegen(c) microarrays; and, (5) extending and testing two-locus population genetic theory to a new model of speciation based on interactions between a pair of genes, one with maternal and one with zygotic expression. Our extensive preliminary studies, crossing pairs of populations from North and South America, Africa and Asia, have revealed that dominance, epistasis, maternal genetic effects, and genotype-by-environment interaction cause morphological and behavioral abnormalities and reduced viability and fertility in inter-population hybrids. For the most extreme case of hybrid fitness reduction, we have shown, through repeated back-crossing to the genome strain, GA-2, and microsatellite marker mapping, that a specific pair of genes interacts to reduce hybrid fitness. We have also shown that inter-population behavioral abnormalities occur in matings and backcrosses between a different pair of populations; that they are not caused one of the genes responsible for the extreme reduction of hybrid fitness (above); and that they involve the breakdown of linked gene combinations. By continuing our back-crosses to the genomic strain, we can isolate the gene combinations causing the behavioral abnormalities in a common genetic background, confirm their functional identity, and characterize their evolution within and among species.