On the constancy of the evolutionary rate of cistrons
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The variations of evolutionary rates in hemoglobins and cytochrome c among various lines of vertebrates are analysed by estimating the variance. The observed variances appear to be larger than expected purely by chance.
If the amino acid substitutions in evolution are the result of random fixation of selectively neutral or nearly neutral mutations, the evolutionary rate of cistrons can be represented by the integral of the product of mutation rate and fixation probability in terms of selective values around the neutral point. This integral is called the effective neutral mutation rate.
The influence of effective population number and generation time on the effective neutral mutation rate is discussed. It is concluded that the uniformity of the rate of amino acid substitutions over diverse lines is compatible with random fixation of neutral or very slightly deleterious mutations which have some chance of being selected against during the course of substitution. On the other hand, definitely advantageous mutations will introduce significant variation in the substitution rate among lines. Approximately 10% of the amino acid substitutions of average cistrons might be adaptive and create slight but significant variations in evolutionary rate among vertebrate lines, although the uniformity of evolutionary rate is still valid as a first approximation.
Key-wordsRate of Evolution Random Fixation Nearly Neutral Mutations
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- Buettner-Janusch, J., Hill, R. L.: Evolution of hemoglobin in primates. In: Evolving genes and proteins, V. Bryson, & H. J. Vogel eds., p. 167–181. New York: Academic Press 1965.Google Scholar
- Crow, J. F., Kimura, M.: An introduction to population genetics theory. New York: Harper & Row 1970.Google Scholar
- Dayhoff, M. O (editor): Atlas of protein sequence and structure. National Biomedical Research Foundation. Maryland: Silver Spring 1969.Google Scholar
- Fitch, W. M.: Systematic Zoology19, 99–113 (1970).Google Scholar
- Haldane, J. B. S.: Evolution3, 51–56 (1949).Google Scholar
- —, J. Genet.55, 511–524 (1957).Google Scholar
- Kimura, M.: Ann. Math. Stat.28, 882–901 (1957).Google Scholar
- —, Nature (Lond.)217, 624–626 (1968).Google Scholar
- Kimura, M.: Proc. nat. Acad. Sci. (Wash.)63, 1181–1188 (1969).Google Scholar
- —, Theoretical population biology2, 174–208 (1971).Google Scholar
- —, Ohta, T.: Genetics61, 763–771 (1969).Google Scholar
- —, —, Nature (Lond.)229, 467–469 (1971).Google Scholar
- King, J. L., Jukes, T. H.: Science164, 788–798 (1969).Google Scholar
- Mayo, O.: Nature (Lond.)227, 860 (1970).Google Scholar
- Nei, M.: Nature (Lond.)221, 40–42 (1969).Google Scholar
- Nolan, C., Margoliash, E.: Ann. Rev. Biochem.37, 727–790 (1968).Google Scholar
- Ohno, S., Wolf, U., Atkin, N. B.: Hereditas (Lond.)59, 169–187 (1968).Google Scholar
- Ohta, T., Kimura, M.: Nature (Lond.), (in press) (1971a).Google Scholar
- - - Jap. Jour. Genet. (in press) (1971b).Google Scholar
- Zuckerkandl, E., Pauling, L.: Evolutionary divergence and convergence in proteins. In: Evolving genes and proteins, V. Bryson, & H. J. Vogel eds., p. 97–166. New York: Academic Press 1965.Google Scholar