Adaptation to the laboratory environment in Drosophila subobscura

Adaptation to a novel environment is expected to have a number of features. Among these is a temporal increase in fitness and some or all of its compo nents. It is also expected that additive genetic variances for these fitnes s characters will fall. Finally, it is expected that at least some additive genetic correlations will decrease, from positive toward negative values. In a study of several life-history variables in a Drosophila subobscura pop ulation sampled from the wild and then cultured in the laboratory, we did n ot find any such longitudinal trends over the first 29 generations. However , a temporal comparison (over 14 generations) of the later generations of t his laboratory-adapted population with a new population, derived from a mor e recent wild-caught sample, indicated clearly that laboratory adaptation w as nonetheless occurring. This study suggests the need for extensive replic ation and control in studies of the features of adaptation to a novel envir onment.