THE number of genes in an organism is one of its fundamental biological parameters and relates to the number of functions required to construct that organism and determine its physiological characteristics. It is generally assumed that with increasing organic complexity the number of genes of the species must increase. The possibility does exist, however, that increasing complexity results from the effects of interactions between a small and relatively constant number of genes. The results presented here support the idea that the number of genes of the insect Drosophila is of the order of 5,000 and therefore not very different from the number of genes estimated for bacteria.

Peer reviewed