Fundamentals of Evolution - Korzh O.P. - 2006

Part II. MACROEVOLUTION

Chapter 16. Modern Problems of Evolution

16.2. Genetic Foundations of Evolutionary Transformations

The first part of this book already touched upon non-Darwinian evolution, which posits that evolutionary changes in organisms are driven not by natural Selection, but by the accumulation of neutral Mutations and the saltational formation of new traits. It should be noted at the outset that Charles Darwin was primarily concerned with THE ORIGIN OF new taxonomic units and The formation of overall organic diversity, rather than individual traits, which serve merely as Qualitative and quantitative Characteristics of Specific taxonomic categories.

Today, numerous researchers have demonstrated that even traits with apparent adaptive significance may or may not fall under the direct control of natural selection, depending on environmental conditions. As for the neutrality of certain mutations (primarily concerning Gene degeneracy), this phenomenon is relative and can only be evaluated in the context of specific living conditions. Rather than being mutually exclusive, "neutralism" and Darwinian natural selection Complement each other, as they pertain to different mechanisms of the evolutionary process.

Until recently, the mutation rate of Chromosomes was considered a constant value. However, recent studies have demonstrated the significant impact of viral infections (such as hepatitis B, measles, encephalitis, Influenza, and others) on The rate of chromosomal mutations. A consequence of such impacts is a surge in mutant genotypes following population-wide viral pandemics. Under conditions of reduced population size, such carriers of chromosomal mutations can constitute a substantial fraction of the population, potentially influencing the subsequent evolutionary trajectory of the respective species.

It is now recognized that chromosomal rearrangements, including polyploidy, are widespread in nature among both plants and animals, and thus significantly influence speciation processes. The Emergence of even a single individual with a new karyotype renders it genetically isolated from its ancestors. To describe such processes, the special term "abrupt speciation" has even been proposed. Nevertheless, although a new genotype arises in a single generation, it cannot yet be considered a distinct species.

The coexistence of diverse (and sometimes fundamentally opposing) viewpoints on many theoretical problems of evolution is entirely understandable. Because their foundations are philosophical in nature and rely partly on belief while drawing upon the same body of evidence, it is difficult to anticipate the emergence of a single scientific consensus that would satisfy all researchers.

One can only speak of the appearance of a new species after population-species characteristics—such as population size, geographic range, and genetic, ecological, and age-sex Structure—have been fully established.

In light of the issues discussed in this section, It is worth revisiting R. Dawkins' concept of "selfish genes." According to his views, individuals of higher organisms are merely vehicles for selfish genes. In the opinion of V. Grant, such assumptions represent an unjustified reductionism and oversimplification far removed from reality.

Any alterations to the genetic material (neutral mutations, macromutations, Horizontal Gene Transfer mediated by Viruses, etc.) fulfill a single primary function: they provide raw evolutionary material. Obviously, the evolutionary process cannot occur without it, yet this material alone is insufficient to drive even the most elementary evolutionary event. Therefore, the theories of neutral mutations, macromutations, viral Transduction, and other reductionist approaches to evolution should be regarded as no more than refinements of the mechanisms that generate diverse genetic material. Its subsequent fate—which is decisive in the formation of new taxonomic categories—is ultimately determined in accordance with the modern principles of the Synthetic Theory of evolution.