Natural and sexual selection in a wild insect population

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.