By Peter Rüegg

Theoretically predicted and now demonstrated experimentally for the first time using soil bacteria: weaker organisms can prevail against stronger ones—if they are superior in number. This acts as a driving mechanism in the maintenance of genetic diversity.

The bacterium Myxococcus xanthus is a microbe with special properties. It lives in soils almost all over the world and is capable of social interactions; that is, individuals join forces to go hunting together for other bacteria and fungi. In times of need, several bacteria from this species can jointly form fruiting bodies with spores that can survive without water or nutrients for a long period of time. This works particularly well with bacteria that are closely genetically related. If the individuals are too genetically different, they might mutually impede and destroy one other.

There are numerous genetic variants and strains of M. xanthus - some more competitive than others. The tendency is for the more competitive strains to get rid of the weaker ones, which in the long run should mean that strain diversity would go extinct. However, in reality, a different picture emerges: even at a distance of only one centimetre, numerous genetically different strains of M. xanthus can be present in the soil. So far, researchers have been able to only speculate as to why and how this diversity is maintained. One theory states that less competitive strains are retained in the population if they can occupy a niche of their own that the dominant bacteria cannot colonise.

Read more at: http://phys.org/news/2015-06-winner-doesnt.html#jCp