Genotype after phenotype? Waddington and the "Genetic Assimilation of an Acquired Character"(discussed Oct 12)

Can an apparently "acquired" character, initially induced by environmental perturbation in the course of development, become a genetically induced trait in a population? Using a series of Drosophila selection experiments, Conrad Waddington answered this question in the affirmative.  By selecting for a heat-shock-induced aberrant wing phenotype, Waddington produced lines that continued to develop the aberrant phenotype in subsequent generations even in the absence of the once-necessary environmental stimulus.  The founding population did not express this phenotype without the heat-shock treatment, but after continuing to breed together only those adults that expressed the phenotype in the absence of heat shock, Waddington eventually produced some lines in which 100% of offspring expressed the phenotype without being exposed to heat shock.  This is the seminal work that inspired far greater understanding and greater interest in the origins of phenotypic novelty and variation and their importance to adaptive evolution.

• The paper: C.H. Waddington 1953. Evolution 7.

Additional reading:
1. Another genetic assimilation paper, in which Waddington expresses his thoughts on the potential evolutionary importance of the phenomenon. 
2. Mary Jane West-Eberhard synthesizing her theory of plasticity-first evolution.
3. A recent TREE article by UNC researchers about plasticity-first evolution.