Selection on behaviour and life histories across generations in a natural population

昆虫构成了动物生物多样性的绝大多数，并且已经在实验室中进行了深入研究，为进化如何运作提供了许多见解。然而，我们在实验室里对进化生物学的了解与我们对自然界中事物实际运作方式的了解之间存在着严重的不平衡。这种差异令人担忧的原因有两个：首先，实验室的情况可能会产生误导，因为它们排除了在野生种群中可能非常重要的选择来源；例如，在实验室里，鸣叫更大声的雄性蟋蟀可能会得到更多的配偶，但在野外，这是通过更有可能被鸟类吃掉来平衡的。其次，我们迫切需要提高对自然种群如何应对环境变化的理解，为此，我们需要对昆虫和脊椎动物进行研究。四年前，我们开始监测西班牙草地上的蟋蟀种群。在过去的两年里，我们对这个种群进行了深入的研究，给每个个体打上标签，用96台摄像机组成的网络记录它们的生活。每个个体的繁殖成功率和跨代关系的模式已经使用DNA指纹技术进行了估计。这已经提供了重要的见解，例如表明雄性在后代数量上比雌性差异更大，并且有很多配偶的雄性所表现出的特征与有很多后代的雄性的典型特征不同。在这个项目中，我们将极大地提高我们的视频监控和我们确定个体之间关系的能力（通过使用新的数码相机技术和新的SNP基因分型技术）。我们将结合多年来关于整个种群的信息，个体之间的关系，它们的生活史，行为和繁殖成功率。这些关于每个个体的全面信息将使我们能够解决我们的主要目标，即确定存在多少遗传变异，以及驱动种群进化的自然选择和性选择是否在多年间保持一致，或者它们是否变化很大。这一点很重要，因为如果某些年份某些类型的个体表现良好，而在其他年份，不同的特征更有利，这将有助于保持遗传变异。这种变异使种群能够适应环境变化，所以我们需要了解有多少以及它是如何维持的。一个相关的目标将是调查人口密度如何影响选择，这是我们只能通过多年的数据来调查的。第二组目标与检验性选择的各个方面有关，这些方面在实验室里已经得到了很好的研究，但在野外却被忽视了。这包括找出特定的雄性和雌性或特定的伴侣对是否更容易成功，因为他们有产生后代的基因，本质上优于其他一些对的后代，或者因为某些个体的组合在基因上更相容，例如，因为他们不是近亲。我们将通过比较一对野生蟋蟀的繁殖成功率和检查它们之间的基因差异来解决这些问题。这也将使我们能够寻找基因的证据，这些基因可以在种群中持续存在，即使它们降低了一种性别的适应性，因为它们增加了另一种性别的适应性，这在实验室中得到了证明，但在野外却很少研究。我们将利用我们掌握的所有蟋蟀的生活史的综合数据来调查像蟋蟀这样的短命动物是真的死于衰老，还是一直活到被什么东西杀死。关于野生无脊椎动物生活的研究很少，所以即使是像这样的重大问题也有待解答

Insects make up the vast majority of animal biodiversity and have been studied intensively in the lab, providing numerous insights into how evolution works. However, there is now a serious imbalance between what we know about evolutionary biology in the lab and what we know about how things actually work in nature. This discrepancy is a source of concern for two reasons: Firstly, laboratory situations may be misleading as they remove sources of selection that may be very important in wild populations; for instance, it may be that male crickets that sing louder get more mates in the lab but in the field this is balanced by being more likely to be eaten by birds. Secondly, we urgently need to improve our understanding of how natural populations can respond to environmental change, and for this, we need studies of insects as well as vertebrates. Four years ago we began monitoring a population of field crickets in Spanish meadow. Over the last 2 years we have studied the population intensively, tagging every individual and recording their lives using a network of 96 video cameras. The reproductive success of every individual and the pattern of relationships across generations have been estimated using DNA fingerprinting techniques. This has already provided important insights, such as showing that males vary more than females in how many offspring they have and that the traits displayed by males that have lots of mates are different from the traits typical of males that have lots of offspring. In this project we will dramatically improve our video monitoring and our ability to determine the relationships between individuals (by using new digital camera technology and new SNP genotyping techniques). We will combine information across years about the population as a whole, how individuals are related, their life histories, behaviour and reproductive success. This comprehensive information about every individual will allow us to address our major aims of determining how much genetic variation is present and whether natural and sexual selection, which drive evolution in populations, are consistent across years or whether they vary a lot. This is important because if in some years certain types of individual do well, whereas in others, different traits are more advantageous, this will help maintain genetic variation. Such variation allows populations to adapt to environmental change, so we need to understand how much there is and how it is maintained. A related aim will be to investigate how population density affects selection, something that we can only investigate with data from a number of years. A second set of objectives relate to examining aspects of sexual selection that have been well studied in laboratories, but neglected in the wild. These include finding out whether particular males and females or particular pairs of mates tend to be more successful either because they have genes that produce offspring that are intrinsically superior to the offspring of some other pairs or because certain combinations of individuals are more genetically compatible with one another, for instance because they are not close relatives. We will address these questions by comparing the reproductive success of pairs of wild crickets and examining how they differ genetically from one another. This will also allow us to look for evidence of genes that can persist in populations even though they reduce the fitness of one sex, because they increase the fitness of the other sex, something that has been demonstrated in the lab, but little studied in the wild. We will use the comprehensive data we have on the life histories of all the crickets in our population to investigate the question of whether short lived animals such as crickets actually die of old age, or whether they just keep going until something kills them. There are very few studies of the lives of wild invertebrates so even major questions like this remain to be answered