  The Weismann barrier, or the impossibility of inheritance of acquired traits,
comprises a foundation of modern biology, and it has been a major obstacle in
establishing the connection between evolution and ontogenesis. We propose the
cooperative model based on the assumption that evolution is achieved by a
cooperation between genetic mutations and acquired changes (phenotypic
plasticity). It is also assumed in this model that natural selection operates
on phenotypes, rather than genotypes, of individuals, and that the relationship
between phenotypes and genotypes is one-to-many. In the simulations based on
these assumptions, individuals exhibited phenotypic changes in response to an
environmental change, corresponding multiple genetic mutations were
increasingly accumulated in individuals in the population, and phenotypic
plasticity was gradually replaced with genetic mutations. This result suggests
that Lamarck's law of use and disuse can effectively hold without conflicting
the Weismann barrier, and thus evolution can be logically connected with
ontogenesis.
