Is the frozen plasticity theory in its original form still valid?
The frozen plasticity theory published in 1998 in Riv Biol -Biol Forum 91:291-304 is still valid in principle, however, not in all details. The major modification concerns the mechanism of the transition from an elastic to a plastic state. The original model suggests that most genetic polymorphism (the major obstacle to adaptive evolution in sexual species) disappears due to a drastic reduction of the population size during peripatric (or, e.g., chromosomal) speciation due to the bottleneck effect. The current version of the frozen plasticity theory assumes that the most important part of genetic polymorphism, i.e., the genes (more correctly the alleles) which are sustained in the population due to frequency-dependent selection, is eliminated in the second phase of speciation by genetic drift, i.e., when the new population balances on the edge of extinction for several generations.