Expression of genetic and environmental variation during ageing : 2. Selection for increased lifespan in Drosophila melanogaster.

A selection experiment with Drosophila melanogaster was carried out to test some theories of ageing by calculating genetic parameters for a reproductive fitness trait at different ages. Successful selection for increased lifespan showed that longevity is a trait under genetic control. Positive genetic correlations between early and late fitness were found. These results do not support the pleiotropy theory of ageing which predicts a negative genetic correlation. Both environmental and additive genetic variation clearly increased with age. Increased environmental variation probably reflects the individuals' difficulties in coping with environmental stress. The increase in additive genetic variation supports the mutation accumulation theory of ageing, as well as other theories that postulate increased additive genetic variation with age.