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\n<\/tbody>\n\n<\/tbody>\n\n<\/tbody>\n\n<\/tbody>\nTHE ARROW POINTS DOWN: Life is more than just chemistry and physics. It also includes information. Information is part of biological reality. We can study it from the point of view of molecular biochemistry but also in terms of mathematical relations, logic and transformation.<\/span><\/p>\n Comparison with Computers<\/span><\/strong><\/p>\n There is some analogy with computers. A computer has a shape, dimensions, a chemical composition, physical parameters etc. All of this we refer to as hardware. But there is also software, currently much more expensive than hardware. We have the programs, the databases, the files, the calculation sheets etc. Without the software, a computer is a pile of junk. With the software in place it does not change its shape, weight, or the chemistry of physical parameters, but it becomes functional.<\/span><\/p>\n Working with computers we have learned certain facts about the role of information in dealing with almost anything. We know that a program can become spoiled on its own through faults in the discs that carry the program. We know that we can spoil a program by mistake. We know that it will never correct itself. By accident it will not become better or more useful. After an accidental change the number of functions a program has will not increase. We know also that an error can protect a word or file from being erased when deletion is commanded. A computer program has an intended plan, a purpose meant for it by the programmer. There is an intelligent input.<\/span><\/p>\n Breeders<\/span><\/strong><\/p>\n Similarly a breeder has a plan, a purpose, and a direction for the intended improvement. However, a breeder does not create new information. He only selects among the information available in nature and strives for such a combination of it so as to direct the breeding program towards the desired improvement.<\/span><\/p>\n Natural reproductive processes maintain biodiversity through recombination. Natural selection acts on existing forms. It reduces the number of forms by eliminating genotypes that are not adapted in the given environmental conditions. It does not create anything new. Breeders replace natural selection with their own, favoring what meets human needs.<\/span><\/p>\n Physicists<\/span><\/strong><\/p>\n In the physics of micro- and macro-cosmos there are doubts about the probabilistic model of explaining reality. There is a school of thinking that favors an information model. They speak of the Unitary Information Field Approach (UIFA) assuming that somewhere there is information that is being realized in the functioning of the cosmos. They envy biologists that have found their Information Field in the genetic code. It needs to be pointed out that we have known where this information is located only since mid 20t<\/sup><\/span>h <\/span><\/sup>century. When the theory of evolution was proposed, and during the time its role in dominating biological thinking developed the most, we had no idea that information for the realization of biological systems existed and was specifically located in a particular place within a living cell.<\/span><\/p>\n Fate of Information<\/span><\/strong><\/p>\n Now let us look at what happens to the information accumulated in the genetic code during the functioning of biological systems, or when man manipulates these systems. In Table 1, some of these biological functions and human activities are listed, segregated into those that reduce information, mix information and increase information.<\/span><\/p>\n Table 1. Fate of information in living systems.<\/span><\/p>\n --------------------------------------------------------------------------------------------------------<\/span><\/p>\n INFORMATION<\/span><\/strong><\/p>\n -------------------------------------------------------------------------------------------------------- Reduction of Information<\/span><\/strong><\/p>\n Isolation of a biological population will lead to a reduction of genetic information. Inbreeding is the consequence of isolating a population. Sexual reproduction occurs between relatives and, in extreme cases, we see self-pollination. This always leads to accidental loss of some information. This loss of some genes is referred to as genetic drift. <\/strong>(This can be compared to the accidental reduction in the number of surnames in a small group of colonists who are left without new arrivals for several generations. Such a phenomenon was known to have occurred on several Caribbean Islands during the 18th and 19th centuries). A gene once lost is lost forever. It does not reconstitute itself. It can only reappear if it is reintroduced.<\/span><\/p>\n Selection acts much faster. Forms that are not adapted to a given environment will perish together with their genes responsible for the lack of adaptation. As a result a population develops that is adapted to the specific conditions of the place, adapted in the sense that it is deprived of the genotypes that are unable to live in this environment. The gene pool is reduced relative to the one it was derived from. One can observe some vegetation on industrial spills. Many seed fall there, but only a few survive. The population that develops there may be adapted to the spill, e.g., a high level of heavy metals, but it is genetically much poorer than the population of seed that fell on the spill.<\/span><\/p>\n Based on this adaptation mechanism, much work has been done by breeders leading to the domestication of plants and animals. The domesticated plants and animals are genetically poorer that the wild organisms they were derived from. When we speak of genetic improvement we mean \"improvement\" from the human point of view. The yield of sugar from sugar beets is increased or the yield of milk from a cow. But this is always at the expense <\/span>of some other functions, and results in the \"improved\" varieties becoming less able to live in natural conditions, becoming dependent on man. The more improved the varieties, the more dependent on humans they are and the poorer they are in genetic diversity.<\/span><\/p>\n Breeding, as well as natural adaptation, leads to the formation of races. Races are genetically poorer than populations they were derived from. All races of dogs can be bred from wild wolves, but it is not possible to breed a St. Bernard from a terrier.<\/span><\/p>\n It is of course well known that mutations can destroy genes. Since mutagenic agents (radiation, chemicals) bombard us all the time, the number of damaged, and therefore defective genes in any population increases. We speak of an increase in the <\/span>genetic load. <\/span><\/strong>When such defective genes meet in a homozygote, the defect shows, and natural selection eliminates the genotype with the defect.<\/span><\/p>\n Reshuffling of Information<\/span><\/strong><\/p>\n Population genetics recognizes recombination of genes as the primary source of variation in nature. It is universally accepted that panmixy occurs in nature. Panmixy is the random meeting of gametes in the process of sexual reproduction. Each gamete (pollen grain, sperm, ovule, egg cell) has its own genetic identity, and therefore, when two combine, a new entity arises.<\/span><\/p>\n In extreme cases we have hybridization, the meeting of gametes from different species. When the hybrid is viable and fertile with one of the parental species we get introgression, the entering of genes of one species into the population of another.<\/span><\/p>\n Transformation is the transfer of genes from one population to another by some other method than through sexual reproduction. A parasite may introduce its genes into the<\/span> <\/span>genome of the host to use its metabolism for its own purposes. A sawfly will cause a willow leaf to produce a gall that is useless for the willow but is a home for the sawfly. The genetics of the willow was modified. Its metabolic potential was utilized according to genetic information from a foreign entity. Now we do the same in genetic engineering. We transfer genes from a fish to a tomato. We produce modified organisms referred to as transgenic. We mix genes from organisms that do not hybridize in nature.<\/span><\/p>\n In sexual reproduction we observe a mechanism for the mixing of genetic information at the reduction division. During meiosis the information inherited from the father and the mother is reshuffled. During pachytene, crossing over of chromatid parts occurs. During anaphase, homologous chromosomes separate and, together with the parts exchanged during crossing over, they travel to the opposite poles. In the process the chromosomes (or their parts) originating from father and mother get mixed so that each resultant haploid gamete is genetically different.<\/span><\/p>\n If a haploid gamete contains a gene that is not adapted to a particular environment or in some way defective, this will cause difficulties to the gametophyte, resulting in it being impoverished or simply perishing. In this way defective or non\u00adadapted genes get lost. However after fertilization, in a diploid zygote and the resultant sporophyte, the non-adapted or defective gene can survive, thanks to the presence of a functional homologous one from the fertilization partner. This is referred to as dominance of some genes over recessive ones. The net result is heterozygocity or genetic biodiversity in the population. This is a natural mechanism for the protection of genes useless in a given environment, but possibly useful in another, in which some descendant will happen to live. Unfortunately this is also a mechanism that protects defective genes, the <\/span>genetic load<\/strong>,<\/strong> <\/strong><\/span>as it is called.<\/span><\/p>\n Gene mixing results also from plant and animal migration. Each species constantly places some of its progeny beyond its current range of occurrence. Man also frequently transfers populations beyond their natural ranges. The new arrivals, whether naturally or artificially introduced, if they find it possible to interbreed with the local populations, become a source of an increase in the genetic biodiversity. As new territories are being colonized by a species, sometimes separate waves of colonization from different refugia <\/span><\/em>meet, and then recombination between them occurs, giving a rich genetic diversity of the population.<\/p>\n Seeing the genetic resources of our planet decline, man has made efforts to protect them. We now often speak about the protection, or even promotion, of biodiversity. It needs to be stressed that breeding and gene pool protection have opposite effects on genetic information. However, in breeding work it is possible to deliberately increase heterozygocity to assure greater stability of the improved population. Highly bred pure lines are especially hybridized to achieve heterozygocity. The breeding population is often deliberately kept diversified to counteract the loss of genes accompanying selection.<\/p>\n Highly bred and improved plants and animals need human protection. Usually they need special environmental conditions that only man can supply (fertilizers, fodder, antibiotics, pesticides, herbicides etc.). But not only that. They require human protection from outbreeding. They have to be kept isolated. Once the isolation is discontinued, we get mongrels; selected varieties go wild.<\/p>\n Increase of Information<\/span><\/strong><\/p>\n There is only one mechanism that is credited with increasing genetic information. It is mutagenesis. It is assumed that once in a while a mutation occurs that is positive, in the sense that it increases the survival potential of the individual, and of the population derived from it. A positive mutation is the only <\/span>possible source of new information. The whole theory of evolution hinges on the existence of positive mutations. But do we have good examples of them?<\/p>\n Darwinian Evolution<\/span><\/strong><\/p>\n Darwin observed variation within species (beaks of finches). He observed adaptation to various environments and diversification of isolated populations (now referred to as genetic drift). What he observed was the consequence of recombination and of reduction of genetic information. Yet his conclusion was Evolution, <\/span><\/em><\/strong>a natural process giving growth of information.<\/p>\n His conclusion was wrong! Adaptation, often referred to as microevolution, is not an example of a small step in macroevolution. It is a process in the opposite direction!<\/p>\n In school textbooks the world over we find the example of the peppered moth Biston betularia <\/span><\/em>that sits on the bark of birch trees. It was found to change its color to black when, in industrial areas, the bark of birches was soot covered. When the industrial soot was cleaned up, the peppered moth returned to its whitish gray color. This is an example of adaptation, reversible adaptation, since there was a breeding link with wild populations living outside the polluted area. Natural selection, birds feeding on the moths, leaves only those that are least seen when sitting on the birch bark. Genes for the dark color are present in the wild population and dominate it when environmental conditions demand it. The dark colored race has no new genetic information. It has only a portion of the information present in the wild genetic pool. In fact, only proportions of black and gray moths change. These are differences in numbers, not in kind.<\/p>\n
THE ROLE OF INFORMATION IN BIOLOGY
<\/span><\/strong>B<\/strong>y<\/strong><\/span>
<\/span>Dr. Maciej Giertych<\/strong><\/span><\/span><\/p>\n
<\/span>Reduction Recombination Growth<\/span><\/strong>
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<\/strong><\/span>Isolation Panmixy
Inbreeding, self-pollination Hybridization, introgression
Transformations, engineering
Genetic drift Meiosis, crossing-over
Selection Heterozygocity protects recessives
Adaptation Migration
Domestication Protection of gene resources
Improvement Care for biodiversity
Breeding Increasing heterozygocity
Race formation Going wild, mongrelization<\/span>
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<\/span>Deleterious mutations Positive mutations<\/span>
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