Never too late to mate? Evolution of timing of attraction as a driver of species diversification

你周围的世界以每日的节奏变化：白天的光明和温暖被夜晚的黑暗和寒冷所取代。大多数雌蛾只在晚上才会在空气中充满信息素。在凌晨4点几乎不可能找到健康的食物。掌握一个24小时的节律来预测并应对这些环境变化对任何生物都是有益的(例如，雄蛾只在晚上寻找雌性，许多人类在白天进食)。因此，几乎所有生物体都显示出其生命过程的每日节奏，例如，基于内部生物钟的睡眠-觉醒周期，这也就不足为奇了。尽管特定栖息地的环境变化对所有居民都是一样的，但一些物种已经进化成白天活动，而另一些物种则是夜间活动。即使是生活在同一栖息地的亲缘关系密切的物种，它们的日常活动节奏也可能有所不同。尽管人们对昼夜节律的分子基础有了越来越多的了解，但日常活动模式的分化进化在很大程度上还没有被探索。哪些分子变化是行为时间变化的基础？在男性和女性中，分子变化是否导致相同的表型，或者某些变化是否存在性别特异性？如果一个种群的时间发生了变化，这是否会有效地阻止这个种群的个体与另一个种群的个体交配，最终推动新物种的形成？夜蛾Spotor tera rugiperda是解决这些问题的理想生物。它作为两个交配品系出现，它们交配的时间不同：所谓的玉米品系在深夜交配，而所谓的水稻品系在深夜交配。在这个拟议的项目中，我们将通过量化不同种群中不同菌株在行为时间和昼夜节律基因上的差异来确定田间存在的时间隔离。我们还将通过利用不同雄性信息的回交的RAD序列进行精细定位来鉴定时序分化的遗传基础。得到的候选基因(S)将通过使用CRISPR/CAS9编辑它们并分析产生的基因表达和行为差异来进行功能表征。由于性别差异表达差异可能是导致时序差异的一种可能机制，我们还将比较雄性和雌性之间时钟基因的表达。综上所述，本项目将揭示果蝇时间隔离背后的分子机制，并评估时间隔离对品系差异的贡献。它将促进我们对面对基因流的物种形成和(交配)行为差异时机的进化的理解。

The world around you changes in a daily rhythm: The light and warmth of the day is superseded by the darkness and chill of the night. Most moth females will fill the air with their pheromone only at night. It is almost impossible to find a healthy meal at 4 in the morning.It is beneficial for any living being to acquire a 24-hours rhythm to predict these environmental changes and cope with them (e.g. by moth males searching for females only at night und many humans eating during the day). Hence it is no surprise that almost all organisms do show a daily rhythm of their life processes, e.g. the sleep-wake cycle, based on an internal circadian clock. Even though the environmental changes in a given habitat are the same for all inhabitants, some species have evolved to be day-active, while others are night-active. Even closely related species living in the same habitat can differ from each other in their daily activity rhythms. Despite a growing knowledge on the molecular basis of circadian rhythms, the evolution of differentiation in daily activity patterns is largely unexplored. Which molecular changes underlie a change in the timing of behavior? Do molecular changes lead to the same phenotype in males and females, or is there a sex-specificity for some changes? If timing has changed in one population, could this effectively prevent individuals from this population from mating with individuals from a different population, ultimately driving the formation of new species?The noctuid moth Spodoptera frugiperda is an ideal organism to address these questions. It occurs as two sympatric strains that differ in their timing of mating behavior: The so-called corn-strain mates early in the night while the so-called rice-strain mates late in the night. It is hypothesized that the strains are undergoing speciation in sympatry and that their temporal differentiation plays a key role in this process.In this proposed project, we will determine the temporal isolation present in the field by quantifying strain-specific differences in timing of behavior and circadian rhythm genes in different populations. We will also identify the genetic basis of the timing differentiation by fine-scale mapping using RAD sequences of different male-informative backcrosses. The resulting candidate gene(s) will be functionally characterized by editing them using CRISPR/Cas9 and analyzing resulting gene expression and behavioral differences. As sex-specific expression differences are one possible mechanism that could underlie the timing diversification, we will also compare clock gene expression between males and females.In summary, this project will shed light on the molecular mechanisms underlying temporal isolation in Spodoptera frugiperda and evaluate the contribution of the temporal isolation to the strain divergence. It will advance our understanding of speciation in the face of gene flow and of the evolution of differential timing of (mating) behavior.