Natural and sexual selection in a wild insect population

为了理解为什么动物种群在大小和分布上会发生变化，以及为什么个体会这样做，了解进化是如何发生的是至关重要的。在过去的几十年里，生态学研究中一个真正成功的故事是对哺乳动物和鸟类的长期研究，在这些研究中，跟踪个体及其后代和他们的后代等等是可能的。通过传递基因来衡量个体成功的能力，使研究人员能够解决特定特征如何影响生殖成功，从而推动进化的问题。例如，对达尔文雀类的研究已经能够证明进化的发生，因为特定的喙形状在特定的气候条件下是有益的。我们建议为少数哺乳动物和鸟类增加一个全新的野外系统，这些动物和鸟类到目前为止在自然界中已经得到了彻底的研究。我们将使用数码摄像机和麦克风组成的网络来监控西班牙草地上一群单独标记的田野蟋蟀。在实验室里对蟋蟀进行了充分的研究，揭示出它们有复杂的性别选择形式，雌性根据它们的歌声在雄性之间选择，雄性打架，雌性操纵几个雄性的精子来偏袒无关的雄性，等等。然而，尽管我们现在对实验室中蟋蟀的行为和生理有了很多见解，但我们几乎不知道这些方面在现实世界中有多重要。这种差异是一个令人担忧的问题：实验室的情况消除了一些在野生种群中可能非常重要的选择来源，并可能产生新的压力；例如，可能是唱歌声音更大的雄性在实验室获得了更多的配偶，但在野外，这样的雄性可能更有可能被鸟吃掉。蟋蟀的这些问题与几乎所有其他模型系统都是相同的：无一例外地，在野外研究得很好的物种太难在实验室中研究(例如马鹿、大山雀)，而在实验室中研究得很好的物种(例如果蝇、柄眼蝇)在野外研究得很少。现在迫切需要的是一个弥合这一鸿沟的体系。技术的进步意味着这样的研究现在是可能的。我们建议使用80个摄像头来监控一小群蟋蟀的大多数活动：谁和谁交配，谁打赢了比赛，每个雄蟋蟀唱了多少歌，每个人活了多久，等等。这将与种群中每个成虫的DNA采样相结合，这将使我们能够计算出每个个体在下一代成虫中留下多少后代。基于我们的遗传标记的模拟表明，我们的谱系至少将与大型脊椎动物的教科书研究中使用的谱系一样可靠。监测和亲子分配的结合将使我们能够解决进化生态学中的一些关键问题：1.雄性更多地依赖于他们的交配能力，而不是他们的生存能力？2.雄性在繁殖成功方面是否比雌性差异更大？3.雄性交配成功是因为他们对雌性有吸引力，还是因为他们善于与其他雄性打架？4.花费大量精力获得交配的雄性是否会付出更短的寿命的代价？5.与有吸引力的雄性交配的雌性有更健康或更有吸引力的后代吗？6.有一些基因对一个人有利吗？性别对另一方有害吗？7.基于实验室对性状遗传的估计是否与田间估计相符？8.相关昆虫曾经相遇过吗？如果他们相遇，它们彼此交配吗？在蟋蟀身上回答这些问题将提供跨物种的洞察力，并为现代生物学的一个中心范式的有效性提供至关重要的见解，即我们可以在实验室中进行行为生态学。

To understand why animal populations change in size and distribution and why individuals behave as they do, it is essential to understand how evolution occurs. Over the past few decades a real success story in the study of ecology has been the long-term studies of mammals and birds where it has been possible to follow individuals and their offspring and their offspring's offspring and so on. The ability to measure individual success in passing on their genes has enabled researchers to address questions about how particular traits affect reproductive success and hence drive evolution. For instance, studies of Darwin's finches have been able to demonstrate evolution occurring because particular beak shapes are beneficial under particular climatic conditions. We propose to add a completely new field system to the handful of mammals and birds which have thus far been thoroughly studied in nature. We will use a network of digital video cameras and microphones to monitor a population of individually marked field crickets in a Spanish meadow. Crickets have been well studied in the laboratory, revealing that they have complex forms of sexual selection whereby females choose between males according to their songs, males fight, females manipulate sperm from several males to favour unrelated males and so forth. However, although we now have many insights into the behaviour and physiology of crickets in the laboratory, we have almost no idea how important these various aspects are in the real world. This discrepancy is a source for concern: Laboratory situations remove some sources of selection that may be very important in wild populations and may create new pressures; for instance, it may be that males that sing louder get more mates in the lab, but in the field such males may be more likely to be eaten by birds. These issues with crickets are shared with almost all other model systems: without exception the species that are well studied in the field are too difficult to study in the lab (e.g. Red Deer, Great Tits), and the species that are well studied in the lab are poorly studied in the field (e.g. Fruit Flies, Stalk Eyed Flies). What is desperately needed is a system that bridges this divide. Advances in technology mean that such a study is now possible. We propose to use 80 cameras to monitor the majority of activity occurring in a small population of crickets: who mates with whom, who wins fights, how much each males sings, how long individuals live and so on. This will be combined with DNA sampling of every adult in the population which will allow us to work out how many offspring each individual leaves in the next generation of adults. Simulations based on our genetic markers show that our pedigree will be at least as reliable as those used in the text-book studies of large vertebrates. The combination of monitoring and parentage assignment will allow us to address some key questions in evolutionary ecology: 1. Do males depend more on their ability to get matings than their ability to survive? 2. Do males vary more in their reproductive success than females? 3. Is male mating success due to them being attractive to females or good at fighting with other males? 4. Do males that devote a lot of effort to getting matings pay a price in terms of shorter lifespan? 5. Do females that mate with attractive males have healthier or more attractive offspring? 6. Are there some genes that are beneficial for one sex but detrimental to the other? 7. Do lab based estimates of the inheritance of traits match estimates made in the field? 8. Do related insects ever meet and if they do, do they mate with one another? Answering these questions in crickets will provide insights across species and provide crucial insights into the validity of a central paradigm of modern biology which is that we can do behavioural ecology in the lab.