23 Evolution of Behavioral Genes

Abstract

Behavioral genetics has come a long way since it started to be taken semi-seriously in the 1950s. In the early days, selection experiments and studies of highly inbred strains tended to provide the major experimental approaches. These had a distinctly evolutionary flavor in that crosses between selected or inbred lines would be used to determine the “genetic architecture” of a phenotype, and to provide some indirect evidence for the selective forces underlying the trait in question, be it sexual behavior in flies or aggression in mice (Hay 1985). In the 1970s, Seymour Benzer advocated the “neurogenetic” approach with its emphasis on single genes, and which used behavior as an entrée into the dissection of the nervous system of the fruit fly, Drosophila melanogaster (Benzer 1971). With the coming of the molecular era in the 1980s, the cloning and sequencing of these “behavioral” genes, allied to the transgenic technology mediated by P-elements, added a further spectacular dimension to fly neurogenetics. This has been further exploited by the use of the Gal4/UAS misexpression systems that can be targeted to specific neurons (Brand and Perrimon 1993). Thus, the “brain to behavior” pathway in the fly can now be analyzed at almost all biological levels, from DNA through biochemistry, cellular biology, anatomy, and physiology. However, similar technical developments in mice and worms mean that these types of sophisticated manipulations can be extended to vertebrates and nematodes. Finally, the advent of RNAi technology allows the knockdown of genes in more exotic organisms that have not...