THE ECOLOGY OF BEHAVIOURAL CONTAGION IN NATURAL SYSTEMS

点击翻译按钮获取中文摘要

Across the animal kingdom, the transfer of social information shapes almost all aspects of life. Information transmission takes place in many contexts, and may involve direct communication or information spreading via inadvertent social cues, for instance when individuals learn information through observing others. As individuals gain information and adopt new behaviours, this can then be passed onto others, and the behaviour can spread through the society. For instance, in the 1940's, British tits (Paridae) were observed opening milk bottle tops, and this behaviour appeared to transmit across the population. By transmitting from individual to individual, the social spread of behaviour has the potential to cause both short-term changes (such as modifications to foraging behaviour) as well as long-term multi-generational processes (such as the emergence of culture). By definition, social transmission depends upon the fine-scale social connections between individuals, and the 'social networks' of many animal societies are known to hold much relevance to the spread of behaviour. Nevertheless, the mode by which behaviour spreads, and the factors that shape this, remain less well understood. In particular, two contrasting hypotheses exist. A long-held hypothesis formed in the 1970's which has been highly influential across diverse systems (ranging from computational networks to animal societies) argues that weak social links often bridge the network and therefore enable increased diffusion potential in contrast to strong links that are usually between individuals who are connected within small clusters - or cliques - anyway. However, a more recent hypothesis that is currently revolutionizing the sociology of behaviour spread states that if adopting a behaviour requires social reinforcement, then strong ties within clustered cliques of individuals become most important. Yet, testing these hypotheses and examining the social, and ecological factors shaping behaviour spread within animal systems requires (i) large-scale tracking of wild individuals within the same social system, (ii) the ability to monitor behaviour at high resolution and, crucially, (iii) experimental manipulations of the potential governing factors.Here, we will use an exceptionally detailed study of wild birds (great tits) at Wytham, near Oxford, involving thousands of individuals tracked over their entire lifetimes, to understand how behaviour spreads. Our previous work has demonstrated that behaviour is transmitted across social ties between these birds, and that it is possible to manipulate population-level components and individual-level sociality using novel automated selective feeders to control precisely which individuals can feed in each area of the woodland. We will combine our past protocols to allow monitoring and manipulation of individuals' social ties and behaviour to test the way behaviour spreads and how ecological and individual factors influence this. First, by manipulating fundamental ecological factors (density and mixing) we will determine how these affect network structure and the consequences for behaviour spread. Second, we will test how differences in individuals' social characteristics affect the flow of new behaviours by manipulating the social start points of behaviour and the presence of particular individuals. In addition, we will examine how behavioural changes may feedback onto social structure itself. Our overall goal is to develop an integrated understanding of the interplay between ecology, sociality, and the spread of behaviour. These insights can then be used to understand the social consequences of ecological factors, the role of individual characteristics in shaping transmission processes, and allow the prediction how behavioural spread may alter under different scenarios, in changing conditions and when subject to perturbations.