Heritability and threshold determinations of the optomotor response in Drosophila melanogaster

Abstract

The optomotor response to an illuminated, moving striped plate was measured in 104 flies from a wild type population of Drosophila melanogaster. Each fly was given ten opportunities to respond and optomotor scores ranged from zero (no response) to ten. Selective breeding procedures based on low, middle and high scores were instituted to investigate the heritability of these individual differences in optomotor responding. Three strains differing with respect to optomotor behaviour were successfully bred and maintained for thirty generations. The extent to which controlling individual differences with regard to a single value of stripe width and luminance would affect optomotor threshold functions was also studied. Minimum light intensities required to elicit the response for five different stripe widths were determined for the three strains using a method of limits. The resulting curves were identical in shape but displaced along the abscissa, the degree of displacement representing systematic differences between the strains.