Marla Sokolowski Retrospectively.

Marla Sokolowski's scientific achievements established her as an internationally recognized leader in behavioural genetics. As a graduate student, she made a significant discovery while observing natural populations of the fruit fly, Drosophila melanogaster: the larvae exhibited a behavioural polymorphism which she traced to alleles of a single gene. Some larvae were 'sitters' which fed in a restricted location, while others were 'rovers' which ranged more widely in feeding. The gene in question, foraging, codes for a cyclic GMP kinase which is expressed in numerous locations throughout larval and adult Drosophila. Building on this foundation, she and her students have elucidated the genetic and environmental factors that account for individual differences in behaviour. In this article, I review significant stages of her scientific career.