Does sexual selection accelerate adaptation in the wild?

我们的目的是了解性选择（雄性获得受精能力的差异）如何影响种群如何应对变化而进化。这是一个非常广泛的问题，对于理解所有有性繁殖的种群将如何应对环境变化的挑战具有重要意义。虽然性选择最初被认为是为了解释那些似乎会降低存活率的特征，但它也有可能加速适应。如果适应环境的雄性增加了交配成功率，那么有助于这种适应的基因就会增殖，这既通过它们对生存的自然选择贡献（因为适应环境的雄性寿命更长，表现更好），也通过它们对繁殖的性选择贡献（例如，因为适应环境的雄性也有更高的交配率）。已经有一些基于实验室的研究解决了性选择是否会加速或延缓适应的问题，但他们给出了相互矛盾的结果。缺乏的是保留自然背景的实验研究：正是这种背景强加了性选择的真正成本和收益。了解生态适应过程中自然选择和性选择之间的相互作用不仅是进化生物学的一个重要问题，而且对理解种群如何适应不断变化的环境也具有重要意义。例如，如果性选择加速适应，这表明应该对种群进行管理，允许性选择发生。我们将利用我们的“野生蟋蟀”项目，在西班牙的一片草地上进行长期研究，对自然种群的蟋蟀进行实验。该项目具有独特的能力，通过160台数码摄像机和每年一次的DNA指纹采集网络，提供有关人口中每个人生活的详细信息。我们将把种群中的所有雄性替换成从其他种群中繁殖出来的雄性，这样一半来自与我们的草地相似的种群，一半来自条件截然不同的高海拔地区。雄性的性选择要强化自然选择，就要求适应性较差的雄性性选择特征的表达和交配率降低。这是一个非常简单的假设，许多生物学家可能认为它没有争议，但实际上，它只是在现场或实验室以非常有限的方式进行了测试。从根本上说，我们缺乏对这一假设和性选择增加适应性的主要预测的明确检验。一个强有力的测试需要一个实验，直接比较适应良好和不太适应的雄性在整个成年寿命。我们将进行比较，测量性选择特征的表达，雄性实现的繁殖成功和它们后代的自然选择成功。我们将用摄像机监控引进的蟋蟀的整个成年生活，雌性蟋蟀留在草地上，然后在下一个季节回来，对它们的后代做同样的事情。通过DNA指纹鉴定，我们将知道哪个后代来自哪个雄性。只有成功受精的雄性才会留下后代，但父亲之间的成功程度仍然存在差异，这使我们能够比较那些在性选择中成功的父亲与那些不太成功的雄性的后代的寿命和活动。

Our aim is to understand how sexual selection (variation among males in their ability to gain fertilisations) affects how populations evolve in response to change. This is a very broad question with implications for understanding how all sexually reproducing populations will respond to the challenges of environmental change. Although sexual selection was originally conceived to explain traits that appeared to reduce survival, it also has the potential to accelerate adaptation. If males that are well adapted to the environment have increased mating success, then genes that contribute to this adaptation will proliferate, both through their naturally selected contributions to survival (because well adapted males live longer and can perform better) and through their sexually selected contributions to reproduction (for instance because the males that are better adapted to the environment also mate at a higher rate). There have been laboratory based studies that address the question of whether sexual selection will tend to accelerate or retard adaption, but they give conflicting results. What is lacking is an experimental study that retains the natural context: it is this context that imposes the true costs and benefits of sexual selection. Understanding the interactions between natural and sexual selection in the process of ecological adaptation is not only a fundamentally important issue in evolutionary biology, but also has implications for understanding how populations will adapt to changing environments. For example, if sexual selection accelerates adaptation this suggests that populations should be managed to allow sexual selection to occur.We will conduct experiments on a natural population of crickets, utilising our 'WildCrickets' project - a long term study of a meadow in Spain. This project has the unique capacity to provide detailed information about the lives of every individual in the population through a network of 160 digital video cameras and annual DNA fingerprinting. We will replace all the males in the population with males bred from other populations so that half come from populations that are similar to our meadow and half come from high altitude where conditions are very different. For sexual selection on males to reinforce natural selection, it is a requirement that less well adapted males have reduced expression of male sexually selected traits and mating rate. This is a very simple assumption and many biologists probably regard it as uncontroversial, but in reality, it has only been tested in a very limited way in either the field or the lab. Fundamentally, we lack a clear test of this assumption and the arising major prediction that sexual selection increases adaptation. A strong test requires an experiment that directly compares well adapted and less well adapted males over the entire adult lifespan. We will make the comparison, measuring the expression of sexually selected traits, the realised reproductive success of males and the naturally selected success of their offspring. We will do this by using our video cameras to monitor the entire adult lives of the introduced crickets and the females left in the meadow and then coming back the next season and doing the same with their offspring. By using DNA fingerprinting we will know which offspring come from which males. Only males with some success in gaining fertilisations will leave any offspring, but there will still be variation in success amongst fathers, allowing us to compare the longevity and activity of individuals whose fathers were successful in sexual selection with offspring of males that were less successful.