Spite evolves in close quarters, according to research led by Fredrik Inglis of the University of Oxford and ETH, Zurich.
Inglis and his team studied a bacterial species in which individuals sometimes explode, releasing a toxin into the environment that is deadly to competing bacteria.
This kamikaze-like behavior is a bit of an evolutionary mystery. How could a behavior in which an individual gives up its chance to reproduce evolve?
Inglis and his team had previously developed a mathematical model showing that such spite is quite likely to evolve in bacterial colonies that are clonal, meaning individuals share the same genes. The model shows that if a few individuals sacrifice themselves to take out competitors, they increase the chances that their genes (albeit in other individuals) will be passed to the next generation. Lab experiments performed by Inglis and his team support the model.
The experiments further show that spiteful species are most successful when competing with other species for the same resource patch. Spite is far less successful when multiple patches are available. The results, Inglis says, could provide insight into how and when bacteria cause disease.
R. Fredrik Inglis, Patrick Garfjeld Roberts, Andy Gardner, and Angus Buckling, "Spite and the Scale of Competition in Pseudomonas aeruginosa."