Frozen Evolution. Or, that’s not the way it is, Mr. Darwin. A Farewell to Selfish Gene.

In the 19^th century, sexual reproduction was considered to be a mechanism ensuring evolutionary variability, the ability of the species to change in time (Weismann 1889).While the traits of progeny produced asexually are identical with those of their parents (i.e. the inherited traits, not those acquired during the life of the individual), progeny produced by a sexual process exhibit various combinations of the traits of both parents and also traits that are not present in any parent.Modern biology has shown that mutations are the primary source of hereditary variability.On the other hand, in sexual reproduction, segregation andrecombination of alleles in each generation leads to new combinations of alleles that were formerly present in the gene pool.It can be derived from the laws of combinatorics that, for the usual number of recombining loci and usual number of alleles of each gene, it is almost impossible for two independent individuals that would have completely identical genotype and thus the same phenotype to be formed by sexual reproduction during the existence of the species.Thus, at the level of the population, the main source of evolutionarily new features consists in processes accompanying sexual reproduction, i.e. segregation andrecombination, or gene flow (see VII.2.1).The variability of progeny generated through sexual reproduction understandably has great importance for the ecology of the particular species.For example, it allows its members to better utilize resources in the environment and limits their mutual competition.However, its importance is limited from the standpoint of the evolutionary potential of the whole species, i.e. from the standpoint of the ability of the species to change over time and especially to usefully adapt to a varying environment.  New evolutionary features emerging through recombination have low hereditability and disappear again in the next generation as a consequence of segregation of chromosomes during meiosis and recombination of DNA sections during crossing-over.s