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

你周围的世界每天都在变化：白天的光明和温暖被夜晚的黑暗和寒冷所取代。大多数雌蛾只有在晚上才会在空气中释放信息素。几乎不可能在凌晨4点找到一顿健康的饭菜。对于任何生物来说，获得24小时的节奏来预测这些环境变化并科普它们是有益的（例如，雄性蛾只在晚上寻找雌性，而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律，例如基于内部生物钟的睡眠-觉醒周期，这并不奇怪。即使在一个特定的栖息地的环境变化是相同的所有居民，一些物种已经进化到白天活跃，而其他人是夜间活跃。即使是生活在同一栖息地的密切相关的物种，在日常活动节奏上也可能彼此不同。尽管越来越多的知识的分子基础上的昼夜节律，分化的日常活动模式的演变在很大程度上是未开发的。哪些分子变化是行为时间变化的基础？分子变化是否导致男性和女性相同的表型，或者某些变化是否具有性别特异性？如果一个种群的时间发生了变化，这是否可以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？草地贪夜蛾是解决这些问题的理想生物。它发生在两个同域的品系，它们在交配行为的时间上不同：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。这是假设，菌株正在经历物种形成的同域性，他们的时间分化起着关键作用，在这个过程中，在这个拟议的项目中，我们将确定时间隔离存在于该领域通过量化的时间的行为和昼夜节律基因在不同的人群中的菌株特异性差异。我们还将通过使用不同雄性信息回交的RAD序列的精细尺度映射来确定时间分化的遗传基础。将通过使用CRISPR/Cas9编辑它们并分析所得的基因表达和行为差异来功能性地表征所得的候选基因。由于性别特异性表达差异可能是导致时间分化的一个机制，因此我们还将比较雄性和雌性之间的时钟基因表达。总之，本项目将阐明草地贪夜蛾时间隔离的分子机制，并评估时间隔离对菌株分化的贡献。它将促进我们对面对基因流的物种形成和（交配）行为的差异时间进化的理解。

The world around you changes in a daily rhythm: The light and warmth of the day is superseded by the darkness and chill of the night.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.