FIG. 45.7 The effect of genotype at the foraging locus on the feeding behavior of Drosophila melanogaster larvae. (a) When food is present, rover larvae travel farther than sitter larvae. (b) Both types of larvae exist in natural populations. Source: M. B. Sokolowski, 2001, “Drosophila: Genetics Meets Behaviour,” Nature Reviews Genetics 2: 879–