Long-term selection for a quantitative character in large replicate populations of Drosophila melanogaster

Abstract

Reverse and relaxed selection were carried out in sublines which were derived from six replicate lines of Drosophila during 86-89 generations of selection for increased abdominal bristle number, and the reverse selection sublines were reciprocally crossed with selection lines of their origin.The results of serial relaxed selection initiated at different generations of selection confirm that the accelerated responses observed in the selection lines were largely due to deleterious genes, particularly lethals, with large effects on the selected character. The decline in mean bristle number under relaxed selection was not much different between crowded and uncrowded relaxed sublines.Reverse selection initiated at generation 57 was very effective, though it failed to bring the mean back to the base population level, and the genetic differences between replicate sublines (two from each of the six lines) indicate that low bristle number genes were probably rare in the selection lines. The genes which were still segregating after 57 generations of selection, on the average, did not show any directional dominance. The contribution of the X-chromosome to selection response was proportional to its chromosome length.

Fisheries‐induced neutral and adaptive evolution in exploited fish populations and consequences for their adaptive potential

“…Robertson ), but not always, in particular when population size was reasonably large (e.g. Yoo ). We neglected mutations and nonadditive genetic effects in our model, which could replenish additive genetic variance and allow initial mean genotypic values to be restored.…”

Perspective: The Pace of Modern Life: Measuring Rates of Contemporary Microevolution

“…At the other end of the spectrum, studies of laboratory evolution under artificial selection are particularly well suited to obtaining time series and can often measure evolution over many generations (e.g., 76 in maize experiments by Dudley 1977;85 in Drosophila by Yoo 1980; and 10,000 in Escherichia coli by Lenski and Travisano 1994). It is indisputable that time-series data are more informative than simple endpoint comparisons, and investigators should strive to accumulate such series, despite the logistical difficulties encountered when attempting to do so.…”

Evolution of genetic variability in a population of the edible snail, Helix aspersa Müller, undergoing domestication and short-term selection

“…Many experiments have studied losses of genetic variability during long‐term selection (Rasmuson, 1964; Bell & Burris, 1973; Yoo, 1980; Douaire, 1982; Gallego & Lopez‐Fanjul, 1983) but few have concerned short‐term selection experiments. Sorensen & Hill (1982) studied short‐term evolution in two lines of Drosophila melanogaster selected for abdominal bristle number.…”