Genomic evolution in real time: causes and consequences of an adaptive mutation in the wild

表型变异是进化的原材料，是自然选择和性选择的目标。然而，进化只能通过在DNA水平上改变基因频率来进行。我们的建议利用最近发现的适应性形态突变，明确地将基因组水平的变化转化为表型水平的变化，然后在野生种群中受到快速和可量化的进化变化的影响。我们将研究太平洋野蟋蟀的一种突变，这种突变会消除雄性蟋蟀翅膀上的发声结构。雄性通常会歌唱来吸引雌性交配，但在这样做的过程中，它们也会吸引一种致命的、听觉定向的寄生蝇。这种沉默突变，平翅，于2003年在一个野生种群中出现，并在大约20代的时间里迅速传播到接近固定的状态，因为它保护雄性免受苍蝇的攻击。沉默的平翼雄性似乎通过拦截和交配响应的雌性来充当种群中剩余呼叫者的卫星。扁平突变体的快速传播代表了野外有记录以来最快的进化速度之一。这种突变是性染色体上遗传的一种简单的孟德尔特征。我们建议的主要目标是(1)确定突变位于基因组的哪个区域，以及潜在的基因变化，以及(2)表征扁平翅和正常翅雄性蟋蟀之间以及由于沉默雄性的存在或不存在而经历了不同社会环境的蟋蟀之间基因表达的广泛差异。这些目标将使进化生物界更好地了解野外选择所针对的基因组变异类型(例如，编码基因与调控基因)。我们的结果还将展示一个重大的进化事件如何对其他基因的调节和表达产生连锁效应，从而使新的表型性状暴露在选择之下。T.Ocean anicus的研究系统提供了一个很好的机会来展示进化是如何在野外实时进行的，以及单个性状的变化如何引发一系列影响，从而改变基因表达、表型特征和选择压力。

Phenotypic variation is the raw material of evolution and the target of natural and sexual selection. However, evolution can only occur through changes in gene frequencies at the level of DNA. Our proposal capitalizes on a recently discovered adaptive morphological mutation to explicitly link how changes at the genomic level translate into changes at the phenotypic level, which are then subject to rapid and quantifiable evolutionary change in a wild population. We will study a mutation in the Pacific field cricket, Teleogryllus oceanicus, that erases sound-producing structures on male wings. Males ordinarily sing to attract females for mating, but in doing so, they also attract a deadly, acoustically-orienting parasitoid fly. The silencing mutation, flatwing, arose in a wild population in 2003 and rapidly spread to near-fixation over the course of approximately 20 generations because it protects males from attack by the fly. Silent flatwing males appear to act as satellites to the remaining callers in the population by intercepting and mating with responding females. The rapid spread of the flatwing mutation represents one of the fastest rates of evolution ever recorded in the wild. The mutation is a simple Mendelian trait inherited on the sex chromosome. The main goals of our proposal are to (1) identify in what region of the genome the mutation resides, and the underlying genetic changes, and (2) characterize broad-scale differences in gene expression between flatwing and normal-wing male crickets, and between crickets that have experienced different social environments resulting from the presence or absence of silent males. These goals will provide the evolutionary biology community with a better understanding of the type of genomic variation targeted by selection in the wild (e.g. coding genes vs. regulatory genes). Our results will also demonstrate how a major evolutionary event has knock-on effects on the regulation and expression of other genes, thereby exposing new phenotypic traits to selection. The T. oceanicus study system provides an excellent opportunity to demonstrate how evolution works in real time, in the wild, and how change in a single trait initiates a cascade of effects that alter gene expression, phenotypic traits, and selection pressure.