More than 100 years ago, the Nobel Prize-winning geneticist Thomas Hunt Morgan and his colleagues discovered that some fruit flies had inherited genetic mutations that caused their body color to change. Yellow flies had a mutation in a specific gene, and these mutants not only looked different from normal flies, but they also behaved differently.
Specifically, the yellow males were much less successful in mating than the normal males. The reason is not known. Geneticists suggest that mutations in insect pigment genes could change changes in the brain, altering dopamine levels, leading to mating failure .
Beyond the brain
A series of high-speed video and genetic experiments have been used to assess how mutations in male yellow fruit flies affected their mating behavior. The experiments showed that the yellow fruit flies mated poorly not due to changes in their brain but to changes in specialized structures in their legs called sexual combs .
Yellow males lack melanin pigments in their sex combs , which changes their structure. As a result, the yellow males would court the female flies, but then they could not grab and mount them. This explains why yellowflies often do not mate effectively.
The study reveals how important it is for scientists to consider that genes that affect behavior can do so by changing the anatomy rather than altering the brain.
The results can also benefit those working to control insect pests . For example, they could help insect pest managers develop strategies that prevent reproduction in other insects that spread disease or destroy crops.