Genotype-environmental interaction in the activity and preening of Drosophila melanogaster

Techniques, recently developed to analyze genotype-environmental interaction in plants, are used to study the behaviour of two inbred lines of Drosophila melanogaster and their F 1s. The locomotor activity and preening of the hybrids altered far less with age and between two different test conditions than did the behaviour of their homozygous parents. In one apparatus, age affected the additive genetical component leading to heterosis for high activity and, in the other condition, a maternal effect on activity was age-dependent. Preening varied far less with age but, like activity, showed dominance for low inter-individual variability and differences between replicates, due entirely to the unstable performance of one inbred line.In the light of additional evidence on larval-adult survival and on adult viability, it is suggested that a negative correlation exists between viability and responsiveness to many types of environmental variation. Therefore information may be gained by analyzing inter-individual variability, instead of the customary practice of rescaling data to make the variances homogeneous.