Evolution: Not only the fittest survive

Darwin’s notion that only the fittest survive has been called into question by new research published in the journal Nature. A collaboration between the Universities of Exeter and Bath in the UK, with a group from San Diego State University in the US, challenges our current understanding of evolution by showing that biodiversity may evolve where previously thought impossible. The work represents a new approach to studying evolution that may eventually lead to a better understanding of the diversity of bacteria that cause human diseases.

Conventional wisdom has it that for any given niche there should be a best species, the fittest, that will eventually dominate to exclude all others. This is the principle of survival of the fittest. Ecologists often call this idea the `competitive exclusion principle’ and it predicts that complex environments are needed to support complex, diverse populations.

Professor Robert Beardmore, from the University of Exeter, said: “Microbiologists have tested this principle by constructing very simple environments in the lab to see what happens after hundreds of generations of bacterial evolution, about 3,000 years in human terms. It had been believed that the genome of only the fittest bacteria would be left, but that wasn’t their finding. The experiments generated lots of unexpected genetic diversity.”

This test tube biodiversity proved controversial when first observed and had been explained away with claims that insufficient time had been allowed to pass for a clear winner to emerge. The new research shows the experiments were not anomalies.

Professor Laurence Hurst, of the University of Bath, said: “Key to the new understanding is the realization that the amount of energy organisms squeeze out of their food depends on how much food they have. Give them abundant food and they use it inefficiently. When we combine this with the notion that organisms with different food-utilizing strategies are also affected in different ways by genetic mutations, then we discover a new principle, one in which both the fit and the unfit coexist indefinitely.”

Read more here Evolution: Not only the fittest survive.

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One Response to Evolution: Not only the fittest survive

  1. alfy says:

    The phrase, “Survival of the fittest” is a journalists’ term, and has no place in science. It is a tautology, or circular argument. How do you define “fittest”? It can only be defined in terms of survival. Hence the phrase becomes, ” The survival of the ones that survive.”
    I am surprised, but perhaps shouldn’t be, that the Exeter group thought that only one “ideal” species would remain, after many generations.
    In nature there are lots of examples of species clinging on by their fingernails when all logic suggests that they should be extinct.
    Look at classic sickle-cell anaemia. All logic suggest that the normal haemoglobin is the “ideal” variant, and yet we know that the SC variant survives because it confers a degree of protection against malaria. This helps us to understand that genes are not absolutely ideal but it is a relative concept depending on the environmental circumstances. The same is true of species. As environments vary so the selection pressures on different species changes. I appreciate the the Exeter group tried hard to keep everything constant but notwithstanding this there is still room for a range of species, not jiust one “ideal” species. Could it be that they compete in very subtle biochemical ways that are not immediately obvious.

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