Abstract
A simple system was constructed and used in the experimental elucidation of the fate of a mutant emerging in a population. ThreeEscherichia coli strains having the same genetic background except for their glutamine synthetase gene were used as model competitors. The difference in the enzyme gene were introduced by random mutation. Competition between these bacterial strains was carried out and observed in a continuous liquid culture. In most cases, the competitors stably coexist either in a steady state or in an oscillating state. In addition, the competition between the strains was found to be a deterministic process and not a stochastic one. These results showed that an emerging mutant in a population, be it a closely related one to the original members, can attain a state of stable coexistence even in a homogeneous environment. The ability of each of the emerging mutants to maintain its stable coexistence with the original population gives rise to the accumulation of various mutants in a population. Therefore, evolution starts from gradual accumulation of various mutants in the population, which in turn leads to the diversification of the population. As our experimental system is a minimum model for the various competitions in the natural ecosystem, the observed competitive coexistence is proposed to be a general phenomenon in nature.
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References
Abrams, P. (1983) The theory of limiting similarity.Annual Review of Ecology and Systematics 14: 359–376.
Amann, E., J. Brosius and M. Ptashne (1983) Vectors bearing a hybridtrp-lac promoter useful for regulated expression of cloned genes inEscherichia coli.Gene 25: 167–178.
Baltzis, B. C. and A. G. Fredrickson (1984) Coexistence of two microbial populations competing for a renewable resource in a nonpredator-prey system.Bulletin of Mathematical Biology 46: 155–174.
Buchholtz, F. and F. W. Schneider (1985) Selection and coexistence in a bioreactor.Berichie der Bunsengesellschaft fur Physikalische Chemie 89: 165–172.
Butler, G. J. and G. S. K. Wolkowicz (1985) A mathematical model of the chemostat with a general class of functions describing nutrient uptake.SIAM Journal of Applied Mathematics 45: 138–151.
Chang, S.-W. and B. C. Baltzis (1989) Impossible of coexistence of three pure and simple competitors in configurations of three interconnected chemostats.Biotechnology and Bioengineering 33: 460–470.
Chen, Y.-M., K. Bachman and B. Magasanik (1982) Characterization of a gene,glnL, the product of which is involved in the regulation of nitrogen utilization inEscherichia coli.Journal of Bacteriology 150: 214–220.
Fredrickson, A. G. and G. Stephanopoulos (1981) Microbial competition.Science 213: 972–979.
Hansen, S. R. and S. P. Hubbell (1980) Single-nutrient microbial competition: qualitative agreement between experimental and theoretically forecast outcomes.Science 207: 1491–1493.
Hardin, G. (1960) The competitive exclusion principle.Science 131: 1292–1297.
Helling, R. B., C. N. Vargas and J. Adams (1987) Evolution ofEscherichia coli during growth in a constant environment.Genetics 116: 349–358.
Kimura, M. (1983)The neutral theory of molecular evolution. Cambridge University Press, Cambridge.
Kurihara, Y., S. Shikano and M. Toda (1990) Trade-off between interspecific competitive ability and growth rate in bacteria.Ecology 71: 645–650.
Lenski, R. E. and S. E. Hattingh (1986) Coexistence of two competitors on one resource and one inhibitor: a chemostat model based on bacteria and antibiotics.Journal of Theoretical Biology 122: 83–93.
Levin, S. A. (1970) Community equilibria and stability, and an extension of the competitive exclusion principle.American Naturalist 104: 413–423.
Maniatis, T., E. F. Fritsch and Sambrook, J. (1892)Molecular cloning: a laboratory manual. Cold Spring Harbor Laboratory, Cold Spring Harbor.
Novick, A. and L. Szilard (1950) Description of the chemostat.Science 1112: 715–716.
Pahel, G., A. D. Zelenetz and B. M. Tyler (1978)gltB gene and regulation of nitrogen metabolism by glutamine synthetase inEscherichia coli.Journal of Bacteriology 133: 139–148.
Stadtman, E. R. and A. Ginsburg (1974) The glutamine synthetase ofEscherichia coli: structure and control. pp. 755–807.In P. D. Boyer (ed.)The enzymes, 3rd ed., vol. 10. Academic Press, New York.
Xu, W.-Z., J. Fukuhara, K. Yamamoto, T. Yomo and I. Urabe (1994) Random mutagenesis of glutamine synthetase fromEscherichia coli: correlation between structure, activity, and fitness.Journal of Fermentation and Bioengineering 77: 252–258.
Yomo, T., W.-Z. Xu and I. Urabe (1996) Mathematical model allowing the coexistence of closely related competitors at the initial stage of evolution.Researches on Population Ecology 38: 239–247
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Xu, WZ., Kashiwagi, A., Yomo, T. et al. Fate of a mutant emerging at the initial stage of evolution. Res Popul Ecol 38, 231–237 (1996). https://doi.org/10.1007/BF02515732
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DOI: https://doi.org/10.1007/BF02515732