Metrics details Abstract Successive adaptive radiations have played a pivotal role in the evolution of biological diversity 1 , 2 , 3. The effects of adaptive radiation are often seen 4 , 5 , 6 , but the underlying causes are difficult to disentangle and remain unclear 7 , 8 , 9. Here we examine directly therole of ecological opportunity and competition in driving genetic diversification. We use the common aerobic bacterium Pseudomonas fluorescens 10 , which evolves rapidly under novel environmental conditions to generate a large repertoire of mutants 11 , 12 , When provided with ecological opportunity afforded by spatial structure , identical populations diversify morphologically, but when ecological opportunity is restricted there is no such divergence. In spatially structured environments, the evolution of variant morphs follows a predictable sequence and we show that competition among the newly evolved niche-specialists maintains this variation.
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What false predictions tell us about evolution Mutations are not adaptive In the twentieth century, the theory of evolution predicted that mutations are not adaptive or directed. In other words, mutations were believed to be random with respect to the needs of the individual. Their effects are not related to the needs of the organisms.
Pure chance, absolutely free but blind, at the very root of the stupendous edifice of evolution: this central concept of modern biology is no longer one among other possible or even conceivable hypotheses. It is today the sole conceivable hypothesis, the only one that squares with observed and tested fact.
And nothing warrants the supposition—or the hope—that on this score our position is likely ever to be revised. The first problem is that the mutation rate is adaptive. For instance, when a population of bacteria is subjected to harsh conditions it tends to increase its mutation rate.
These hypermutators ensure that an even greater variety of adaptive change is explored. Foster Experiments have also discovered that duplicated DNA segments may be subject to higher mutation rates. Since the segment is a duplicate it is less important to preserve and, like a test bed, appears to be used to experiment with new designs. Wright The second problem is that organisms use strategies to direct the mutations according to the threat.
Adaptive mutations have been extensively studied in bacteria. Experiments typically alter the bacteria food supply or apply some other environmental stress causing mutations that target the specific environmental stress. Burkala, et. Johnson, Moss and Cullis One experiment found repeatable mutations in flax in response to fertilizer levels.
References Burkala, E. Chen, Y. Lowenfeld, C. Schneeberger, C. David, L. Fidalgo, M. Foster, P. Huxley, Julian. Evolution in Action. Johnson, C. Moss, C. Monod, Jacques. New York: Vintage Books. Moxon, E. Orr, H. Wright, B.
Adaptive radiation in a heterogeneous environment
SniegowskiPhilip J. Adaptive Landscapes, Evolution, and the Fossil Record. Adaptive evolution of highly mutable loci in pathogenic bacteria. They typically receive a lot more attention than average, with a mean Attention Score of Catherine Driscoll — — Biology and Philosophy 23 1: Mentioned by blogs 1 blog lpci 1 policy source twitter 7 tweeters wikipedia 1 Wikipedia page. Altmetric has tracked 12, research outputs across all sources so far. Request removal from index.
Adaptive evolution of highly mutable loci in pathogenic bacteria.
Metrics details Abstract Because most newly arising mutations are neutral or deleterious, it has been argued 1 , 2 , 3 that the mutation rate has evolved to be as low as possible, limited only by the cost of error-avoidance and error-correction mechanisms. We consider here whether high mutation rates might playan important role in adaptive evolution. Less potent mutators 10 to fold increase can become fixed in a fraction of finite populations. The parameters of the model have been set to values typical for Escherichia coli cultures, which behave in a manner similar to the model in long-term adaptation experiments 7. Download PDF Main Early models of the evolution of the mutation rate were based on group selection for an optimal compromise between adaptability and adaptedness 2 , 3.