Selection shadow theory of aging

The selection shadow theory or the theory of reduction of the effectiveness of selection during the life of an individual assumes that ageing does not occur in evolution as a mechanism ensuring, in advance, the programmed death of the individual, but rather as a consequence of the existence of an evolutionary barrier consisting in gradual reduction of the effectiveness of natural selection in dependence on the chronological age of the individual. A mutation that acts in the early stages of the life cycle of the individual and that increases the viability of its carrier, for example, by increasing his ability to regenerate damaged tissue, is extremely selectionally advantageous. If this same mutation were to function similarly at a later stage in the life cycle would be substantially less advantageous. This is because all the individuals in the population pass through the early stages of the life cycle, while only those individuals who live long enough and are not, for example, caught by a predator survive to a later stage. While a young individual has all its reproduction in the future, older individuals have already used up part of their reproduction potential. As a consequence of the reduced effectiveness of selection pressure at later stages in the life cycle, mutations that are negatively manifested in these later stages can accumulate in the population through genetic drift while the chance of fixation of mutations that would be manifested positively in these later stages is relatively reduced (Gavrilova et al. 1998).

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The classical Darwinian theory of evolution can explain the evolution of adaptive traits only in asexual organisms. The frozen plasticity theory is much more general: It can also explain the origin and evolution of adaptive traits in both asexual and sexual organisms Read more