Genetic, chemical and behavioral investigation of sexual signaling evolution in parasitoid wasps

进化生物学中最重要的问题之一是新物种可能是如何起源的。物种间繁殖障碍的发展和维持一直被认为是物种形成的主要推动力。一般来说，两种主要的屏障类型可以根据它们在生殖隔离中的功能而被区分，无论是在种间合子形成之前(合子前)还是在种间合子形成之后(合子后)。在昆虫模型系统中，纳斯尼亚是一种具有相当重要农业意义的寄生性宝石黄蜂物种的复合体，作为选择性生物害虫控制，研究充分的合子后生殖隔离与知之甚少的合子后生殖隔离形成对比。无处不在的感染物种特有的沃尔巴克氏菌在很大程度上阻止了这四个迄今描述的物种之间的杂交。然而，在对沃尔巴克氏菌感染进行抗生素治疗后，不同的纳斯尼亚物种重新获得了杂交的能力。这不仅表明了实验上可获得和克服的预合子隔离，而且也构成了研究物种之间复杂适应特征差异的遗传结构的极其有用的研究工具。我以前的研究表明，在Nasonia物种复合体中的角质碳氢化合物(CHC)可以作为物种特有的雌性性信息素，可由雄性区分，暗示着早期的前合子隔离。然而，奇怪的是，在一个物种中，我发现了一个明显是最近的进化飞跃，将女性的CHC图谱移出了雄性的感知范围，而这反过来又保留了对其他物种雌性CHC图谱的潜在祖先吸引力。我们现在有独特的机会从遗传、表型和行为上追踪这一非常不寻常的进化变化，以揭开关键信号化合物的面纱，并获得对潜在机制的整体看法。我们将结合分析化学、行为分析、数量遗传学和功能基因组学来鉴定介导性信息素功能的CHC谱的成分，确定性信息素功能的遗传基础，并分析导致其在四个纳斯尼亚种之间分化的分子和进化机制。

One of the most important questions in evolutionary biology is how new species potentially originate. The development and maintenance of barriers to interspecific reproduction has been postulated to be the major driving force of speciation. Generally, two main barrier types can be differentiated according to their function in reproductive isolation either before (prezygotic) or after (postzygotic) formation of an interspecific zygote. In the insect model system Nasonia, a complex of parasitoid jewel wasp species of considerable agricultural importance as selective biological pest control, well-investigated postzygotic reproductive isolation contrasts far less understood prezygotic reproductive isolation. Ubiquitous infections with species-specific Wolbachia bacteria largely prevent hybridizations between the four hitherto described species. However, after antibiotic treatment of the Wolbachia infections, the different Nasonia species regain the ability to hybridize. This not only indicates experimentally accessible and surmountable prezygotic isolation, but also constitutes an extremely useful research tool for studying the genetic architecture of complex adaptive trait differences between the species. My previous studies demonstrated that cuticular hydrocarbons (CHC) in the Nasonia species complex can function as species-specific female sex pheromones distinguishable by the males, hinting at incipient prezygotic isolation. Curiously though, in one species, I discovered an apparently recent evolutionary leap that shifted the female CHC profiles out of the males’ perceptive range, which, in turn, still retain a potentially ancestral attraction to CHC profiles of females from other species. We now have the unique opportunity to track this highly unusual evolutionary shift genetically, phenotypically and behaviourally to unravel the key signaling compounds and obtain a holistic view on the underlying mechanisms. We will combine analytical chemistry, behavioral assays, quantitative genetics and functional genomics to identify the components of the CHC profiles that mediate the female sex pheromone function, determine the genetic basis of the sex pheromonal function and analyze the molecular and evolutionary mechanisms that have led to its differentiation between the four Nasonia species.