CHANGES IN GENETIC PARAMETERS FOR FITNESS-RELATED TRAITS IN A CAPTIVE POPULATION OF DROSOPHILA MELANOGASTER

INTRODUCTION The genetic architecture of fitness-related traits in Drosophila is usually studied using populations that have been maintained in the laboratory for some period of time, sometimes years (e.g., Ehiobu et al. 1989; Santiago et al. 1989; Garcia et al. 1994). A population in captivity may suffer from the joint action of random drift and adaptation to captivity, with variable outcomes, depending on particular circumstances. For example, frequent bottlenecks occurring in the laboratory may induce a purge of deleterious recessive genes (see, e.g., Wang et al. 1999). In contrast, deleterious recessive alleles may become more common under benign laboratory conditions, as a consequence of adaptation to captivity (Hoffmann et al. 2001; Woodworth et al. 2002). It is therefore possible that the genetic constitution of a captive population substantially differs from the wild population of origin. We compared estimates of genetic parameters for fitness-related traits (additive genetic variance and inbreeding depression) obtained from a recently captured population (Rodriguez-Ramilo et al. 2004) with those obtained from the same population after two years of captivity in laboratory conditions.