Major mutation

In genetics, a large mutation (also known as jump mutation) is a complex change in the genetic make-up which, in a single step, brings about a far-reaching and functioning change in a newly emerging organism. It is not a form of mutation , as the term suggests, but a statistical concept that is used to explain macroevolution .

A major mutation would exist if many mutations occur at the same time and all of them lead to a major change in the organism. This process is very unlikely. No real major mutations have been proven from empirical science. They are particularly controversial as an explanation for the development of animals . This could be due to their rarity, but also to the fact that they cannot occur at all for statistical reasons.

concept

Genetic mutations always cause a gradual change in the organism. The vast majority of all mutations lead to inability to live or to a selection disadvantage for the organism concerned. Only a small number of all mutations always bring about an improvement. However, it is these rare mutations that matter in evolutionary history because they prevail and spread in the gene pool . The worsening mutations disappear again from the common genome of a species.

The concept of the large mutation assumes that it can very rarely happen that several (many) improving mutations can occur simultaneously in an individual. This could, for example, explain not only the improvement in the functioning of an organ, but also the sudden emergence of a completely new organ that functions correctly right away.

In modern biology, the existence of large mutations is largely excluded for reasons of probability. With one improving mutation per 1000 inheritance and 5 mutations required, 10 ¹⁵ inheritance would be necessary for one major mutation. Most corrective mutations, however, require far more than 1,000 inheritances, and most functioning organs are controlled by far more than 5 genes. In vertebrates , for example, with 10 ⁶ inheritance patterns per mutation and 20 new mutations required, 10 ¹²⁰ inheritance patterns would be necessary, a number that can apply beyond all rational assumptions. Correspondingly, however, large mutations can occur in very simple organisms.

Another problem with the major mutation is its inheritance, because it would have to be passed on in full to the subsequent generations, which is made more difficult by recombination during sexual reproduction, because all possible mating partners of the major mutants have the unmutated genetic material and therefore only the original genes can contribute. The offspring of the large mutants would not be inherited in relation to the mutated genes and therefore would not enjoy the associated selection advantage.

The major mutation is one of the saltationist concepts that emerged from overcoming creationism . In contrast to creationist arguments, the major mutation is not considered refuted and has changed the concept to a statistically formable hypothesis. In many cases, however, the hypothesis cannot be checked due to methodological and factual limitations.

Examples of suspected major mutations

The evolution at the tribal level has often been explained by major mutations, because organism tribes often differ in essential characteristics for which no transitional forms appeared conceivable. It has been assumed that the vertebrates ( endoskeleton ) must have emerged from the older invertebrates ( exoskeleton ) through a major mutation , because there is no evidence of animals showing both characteristics. Embryology has shown, however, that here too the changes came gradually into the world. Every vertebrate reproduces this change in its embryogenesis (see gastrulation ).

The Archeopteryx's feathers, which were already capable of flying , were often ascribed to a major mutation. With the discovery of feathered dinosaurs it was recognized that feathers are much older than the ability to fly and, in Archeopteryx, were probably formed through a step-by-step exaptation of simpler feather shapes that were used for thermal insulation.

Grand Mutation and Gradualism

It is considered certain that every organismic characteristic can arise through gradualistic development. Small changes over time lead to big changes. The major mutation is therefore only an additional assumption that cannot be ruled out in individual cases, but is not required for the explanation.

literature

• Günter Staudt A major mutation that occurred spontaneously in fragaria vesca L. In: Naturwissenschaften . Volume 46 (1), 1959, p. 23.