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Survival of the Different

When a simple ancestral population of bacteria is kept in a constant controlled environment, a rich mixture of types evolves rather than a single “winner”.

When a simple ancestral population of bacteria is kept in a constant controlled environment, a rich mixture of types evolves rather than a single “winner”.

By Tom Ferenci

If evolution is about survival of the fittest, why does diversity emerge instead of perfectly evolved organisms that are fit in all environments? Now the complex trade-offs that shape the evolution of diversity have been measured.

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Darwin told us that evolution is about the natural selection of types best fitted to their environment. This is sometimes interpreted as the survival of the fittest, but this is not really true. The emergence of super-fit types is strongly constrained by complex evolutionary forces we do not fully understand. Rather than leading to outright winners, diversity is the most common outcome of evolution.

Plants and animals are diverse enough, but the variety is most extreme with organisms we do not even see: the microbes living in and on us. More than 10,000 different types of organisms are part of the healthy human microbiome. This richness of microbial types reinforces the need to understand two fundamental questions in evolution: how diversity arises, and how it is maintained.

It is has become possible to study both these fundamental questions using bacteria in the laboratory. We can now follow diversification in real time and analyse this fascinating process. The maintenance of diversity can also be dissected by studying the way in which co-existing organisms are generated as a result of trade-offs between evolved characteristics. These trade-offs are crucial in ensuring that perfect, super-fit organisms do not evolve in nature, and diversity is maintained instead.

Our research has demonstrated evolutionary diversification in the laboratory. When we...

The full text of this article can be purchased from Informit.