Love or kill thy neighbor? New study into animal social behavior
Understanding the way in which social behaviours such as altruism — when animals benefit others at their own expense — develop is a long-standing problem that has generated thousands of articles and heated debates.
Dr Florence Débarre of Biosciences at the University of Exeter led a study, published today in Nature Communications, which presents a comprehensive framework that applies to a large class of population structures and identifies the crucial elements which support the evolution of social behaviour.
Structured populations are those exhibiting either spatial or social structure. This can range from animals living in social groups — like meerkats — to bacteria in biofilms.
In these populations altruism evolves if, for individuals, the social benefit of living next to others outweighs the costs of competing against them.
Traditionally, population modellers have assumed that the direct benefits and costs of social interactions affect the ability to produce offspring (the fecundity). In natural populations, however, social interactions may also affect survival.
Dr Débarre and her collaborators combined these two features in their model, which revealed new insights. It turns out that helping your neighbours reproduce more or helping them live for longer does not have the same indirect consequences on your own fitness. These indirect consequences are crucial, and determine which type of social behaviour (helping, harming or doing nothing) can evolve.
When competition is fierce because space is so limited that an individual can only reproduce after some space has been freed up by the death of a neighbour, the researcher’s results show that the social behaviours that are most advantageous are the ones in which individuals make their neighbours die sooner but at the same time help them reproduce. In other terms, the interaction is spiteful when it comes to survival, but altruistic on fecundity. (full article)
F. Débarre, C. Hauert, M. Doebeli. Social evolution in structured populations.Nature Communications, 2014; 5 DOI: 10.1038/ncomms4409
Photo: WWF (x)
An interesting theoretical study on animal behaviour modeling. Unfortunately it is not an open access article but those of you interested in this should check out your local libraries and universities.