Sources of behavioral deviation modeled by early color preferences in quail. II. Diathetic genes and the leftover variance "V(e)".

The sources of deviation from population-typical norms of variability were studied in relation to early approach preferences between colors in newly hatched Japanese quail chicks (Coturnix coturnix japonica). Subjects were drawn from an unselected genetic control line, two genetic lines that were artificially selected for extreme blue and red preferences, their hybrids, and a large set of backcross and assortatively derived generations. Large progressive increases were observed with selection in the leftover (V(e)) component of F1 variance and consistent additional variance increases in F2 hybrids. Backcross generations exhibited greater than expected expression of the blue and red preference genes. Discussion differentiates between diathetic and normative influences in preference deviations and relates the increased Ve to relaxed normative canalization of preference development by directional selection.