1. ¹Programa de Genética Humana, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Independencia 1027, Casilla 70061, Santiago-7, Chile
2. ²Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2UH, UK
3. ³Department of Psychology, University of Sheffield, Sheffield S10 2TP, UK

Correspondence: R Godoy-Herrera, Programa de Genética Humana, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Independencia 1027, Casilla 70061, Santiago-7, Chile. E-mail: rgodoy@machi.med.uchile.cl

Received 21 August 2002; Revised 20 May 2003; Accepted 10 July 2003; Published online 24 September 2003.

Abstract

Larvae of the sibling species Drosophila simulans and D. mauritiana have rates of locomotor and feeding activity that are closely similar. Comparisons of the trait means for intra- and interspecific hybrids show that significant epistatic interactions affect both characters when the genomes of the two species are combined. The phenotypic variances of progenies obtained by backcrossing the interspecific hybrids to their respective parent species show that appreciable genetic turnover affecting foraging behaviour has occurred since their two phylogenetic lines diverged.