| Abstrakt: |
High mortality in every cohort of animals is caused by the cumulative action of all the eliminating effects of components of the implemented ecological niche. This fact creates an impression of very intensive natural selection. Only the reproductive part of population survives, i.e., passes natural selection. This fraction is many times smaller than the entire population. However, every selection vector, determined by abiotic factors, predators, parasites, competition, etc. leads to selection of individuals adapted only to this particular set of biogeocenotic factors. Such selection does not prevent but also does not favor the accumulation of genetic variants with a high adaptive value; it only eliminates those insufficiently fit. The second factor limiting the selection efficiency is low heritability of behavioral, physiological and morphological characters, on which the elimination or survival of organisms mostly depends. The broad reaction norm of such characters provides non-evolutionary adaptation in the course of transformation or development of new ecosystems. Low efficiency of natural selection is responsible for the low rate of coherent evolution, i.e. co-adaptation of the species within communities. Fast, or incoherent, evolution is caused either by the appearance of a new unbalanced selection vector, or by destruction of the existing counterbalanced system which supports the evolutionary stasis in established ecosystems. [ABSTRACT FROM AUTHOR] |
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