Reproductive fitness and artificial selection in animal breeding: culling on fitness prevents a decline in reproductive fitness in lines of Drosophila melanogaster selected for increased inebriation time

Abstract

The maintenance of reproductive fitness in lines subjected to artificial selection is one of the major problems in animal breeding. The decline in reproductive performance has neither been predictable from heritabilities and genetic correlations, nor have conventional selection indices been adequate to avoid the problem. Gowe (1983) has suggested that the heritabilities of reproductive traits are non-linear, with heritabilities being higher on the lower fitness side. Consequently, he has predicted that culling on reproductive fitness in artificial selection lines will be effective in preventing the usual declines in fitness. An experimental evaluation of Gowe's prediction has been carried out by comparing fitnesses of replicated lines of three treatments: selection for increased inebriation time without culling on fitness (HO), selection for inebriation time with culling of 20% (4/20) of selected females on reproductive fitness (HS), and unselected controls (C). Response to selection for inebriation time in the two selection treatments was similar. After 25 generations, the competitive index, a measure of reproductive fitness, was significantly lower in the HO treatment than the HS treatment, while the HS treatment did not differ from the control lines or the base population. These results demonstrate for the first time that culling on reproductive fitness in selection lines can be used to prevent the usual decline in reproductive performance.

Does inbreeding distort sex-ratios?

“…The base (Frankham et al 1988). After 10 generations in captivity, 75 replicate inbred populations were founded and subject to three generations of full-sib inbreeding.…”

Genetic diversity of the cultured giant freshwater prawn (Macrobrachium rosenbergii) in China based on microsatellite markers

“…A population bottleneck is a sharp reduction in size of a population due to environmental random events (such as earthquakes, floods, fires, or droughts) or human activities (William et al, 2009). Population bottlenecks are an important cause of lost genetic variation and can increase chances of inbreeding (Frankham et al, 1988). Bottlenecks have been shown to increase extinction risk in natural populations as well (Newman and Pilson, 1997;Saccheri et al, 1998).…”

Are responses to artificial selection for reproductive fitness characters consistently asymmetrical?

“…Gowe (1983) applied such culling against low fertility and hatchability in lines of chickens selected for increased egg production and apparently was successful in preventing the decline of fertility and hatchability. A systematic evaluation of this approach, involving selection for a trait with and without culling on reproductive fitness, was done by Frankham, Yoo & Sheldon (1988). They showed that culling against low fitness was effective in preventing the usual declines in fitness in lines selected for another character.…”