On the Law of Directionality of Genome Evolution
📝 Abstract
The problem of the directionality of genome evolution is studied from the information-theoretic view. We propose that the function-coding information quantity of a genome always grows in the course of evolution through sequence duplication, expansion of code, and gene transfer between genomes. The function-coding information quantity of a genome consists of two parts, p-coding information quantity which encodes functional protein and n-coding information quantity which encodes other functional elements except amino acid sequence. The relation of the proposed law to the thermodynamic laws is indicated. The evolutionary trends of DNA sequences revealed by bioinformatics are investigated which afford further evidences on the evolutionary law. It is argued that the directionality of genome evolution comes from species competition adaptive to environment. An expression on the evolutionary rate of genome is proposed that the rate is a function of Darwin temperature (describing species competition) and fitness slope (describing adaptive landscape). Finally, the problem of directly experimental test on the evolutionary directionality is discussed briefly.
💡 Analysis
The problem of the directionality of genome evolution is studied from the information-theoretic view. We propose that the function-coding information quantity of a genome always grows in the course of evolution through sequence duplication, expansion of code, and gene transfer between genomes. The function-coding information quantity of a genome consists of two parts, p-coding information quantity which encodes functional protein and n-coding information quantity which encodes other functional elements except amino acid sequence. The relation of the proposed law to the thermodynamic laws is indicated. The evolutionary trends of DNA sequences revealed by bioinformatics are investigated which afford further evidences on the evolutionary law. It is argued that the directionality of genome evolution comes from species competition adaptive to environment. An expression on the evolutionary rate of genome is proposed that the rate is a function of Darwin temperature (describing species competition) and fitness slope (describing adaptive landscape). Finally, the problem of directly experimental test on the evolutionary directionality is discussed briefly.
📄 Content
On the Law of Directionality of Genome Evolution
Liaofu Luo
Laboratory of Theoretical Biophysics, Faculty of Science and Technology,
Inner Mongolia University, Hohhot 010021, China
*Email address: lolfcm@mail.imu.edu.cn
Abstract The problem of the directionality of genome evolution is studied from the information-theoretic view. We propose that the function-coding information quantity of a genome always grows in the course of evolution through sequence duplication, expansion of code, and gene transfer between genomes. The function-coding information quantity of a genome consists of two parts, p-coding information quantity which encodes functional protein and n-coding information quantity which encodes other functional elements except amino acid sequence. The relation of the proposed law to the thermodynamic laws is indicated. The evolutionary trends of DNA sequences revealed by bioinformatics are investigated which afford further evidences on the evolutionary law. It is argued that the directionality of genome evolution comes from species competition adaptive to environment. An expression on the evolutionary rate of genome is proposed that the rate is a function of Darwin temperature (describing species competition) and fitness slope (describing adaptive landscape). Finally, the problem of directly experimental test on the evolutionary directionality is discussed briefly.
1 A law of genomic information The traditional natural sciences mostly focused on matter and energy. Of course, the two are basic categories in the nature. However, parallel to yet different from matter and energy, information constitutes the third fundamental category in natural sciences. One characteristic of a life system is that it contains a large amount of information. Life consists of matter and energy, but it is not just matter and energy. The life of an individual comes from the DNA of its parents. DNA, which weighs only 10-12 gram for human, is insignificant in terms of matter because, like many other things on earth, it is composed of nitrogen, oxygen, sulfur, etc. In addition, DNA, as a source of energy, is also unimportant, since it is just composed of the similar level of chemical energy as other macromolecules that can be produced by experiment. Schrodinger (1944) was the first who recognized the importance of information and indicated that the characteristic feature of life which differentiates from an inanimate piece of matter is the large amount of information contained in its chromosomes. He said, “We believe a gene – or perhaps the whole chromosome fibre – to be an aperiodic solid. With the molecular picture of gene it is no longer inconceivable that the miniature code should precisely correspond with a highly complicated and specified plan of development and should somehow contain the means to put it into operation.” Seventy years have passed. Now, as we try to formulate the basic law of life system we should put our discussion based again on the concept of information. Any building or structure needs a blueprint to be built, this blueprint is the information. A life is a complicated structure. It is like a drama unfolding in a time span. The
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information that represents this dynamic structure is the soul of a life. DNA is a book of
microscopic size that has all basic information about the development, growth and death of a life.
This is also true when the point is examined in terms of the origination of life. Because life only
comes into being when the primitive molecular sequence has evolved for a long time and has
enough information accumulated in it. As we all admire the exquisiteness of the structure and
function of advanced lives on earth, we know that they have all evolved from primitive lives. Each
tiny bit of evolution must be realized through storing information in DNA and changing the DNA
sequence. Therefore, whether we examine the issue from the emergence of individual life or from
that of a species, life starts from information. Lao Tzu said in his Book of Tao and Teh, “It was
from the Nameless that Heaven and Earth sprang, the named is but the mother that rears the ten
thousand creatures, each after its kind.” If the first sentence can be interpreted as: The Universe
starts from nothingness, then the second one means that life starts from information.
Then, what is the basic law of genomic information? The extension of the diversity of species
and their evolution towards higher function more adaptive to environment shows that the life
evolution obeys a law with definite direction. Darwin expressed the law as “survival of the fittest”.
It means that the ‘designed’ properties of living things better adapted to survive will leave more
offspring and automatically increase in frequency from one generation to the next, while the
poorly adapted species will decrease in frequency. Here, the basic point of Darwin’s theory is the
directionality
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