There are many industry examples of genotype by
environment interactions under field conditions;
however, little emphasis has been placed on developing
genetic solutions to these environment- or managementinduced
production problems. Marks (1993) has demonstrated
the potential for genetic adaptation to selection
environment following long-term selection of Japanese
quail for body weight under low- and high-protein
selection environments. Although a greater selection
response was observed in a line (P) selected in a highprotein
environment, this line developed a higher
protein requirement and did not express its full genetic
potential for growth when fed lower protein diets. The
line selected for growth in a low-protein (T) environment
performed equally well under a broad range of
dietary protein levels. However, when lines P and T
were reciprocally crossed, heterosis and even overdominance
were observed for 4-wk BW in all protein
environments tested (Marks, 1995). This result suggests
that a strategy involving selection and crossing of
complementary lines that have been selected under
diverse environmental conditions might optimize
genetic progress and still confer adaptability to a variety
of environmental circumstances