LINEARITY VERSUS NONLINEARITY OF OFFSPRING-PARENT REGRESSION - AN EXPERIMENTAL-STUDY OF DROSOPHILA-MELANOGASTER

An experiment was conducted to investigate the offspring-parent regres sion for three quantitative traits (weight, abdominal bristles and win g length) in Drosophila melanogaster. Linear and polynomial models wer e fitted for the regressions of a character in offspring on both paren ts. It is demonstrated that responses by the characters to selection p redicted by the nonlinear regressions may differ substantially from th ose predicted by the linear regressions. This is true even, and especi ally, if selection is weak. The realized heritability for a character under selection is shown to be determined not only by the offspring-pa rent regression but also by the distribution of the character and by t he form and strength of selection.