Journals of Gerontology Series A: Biological Sciences and Medical Sciences, Vol 50, Issue 5 B262-B269, Copyright © 1995 by The Gerontological Society of America
Effect of adult cohort density on age-specific mortality in Drosophila melanogaster
AA Khazaeli, L Xiu and JW Curtsinger
Department of Ecology, Evolution, and Behavior, University of Minnesota, USA.
Mortality rates decelerate at older ages in experimental populations of
Drosophila. It is unclear whether this reflects a real slow-down in the
aging process, or an artifact of declining density. Mortality was studied
in age-synchronized cohorts of four inbred lines at three initial densities
that varied 10-fold. A total of 70,000 flies of both sexes were studied.
There were large line x density, line, and sex effects, but no systematic
relationship between density and life span was detected. Mortality curves
level off at older ages in 23 out of 24 sex-genotype combinations,
irrespective of initial cohort density. Density has only second-order
effects on the pattern of oldest-old mortality over the range of densities
studied here. The dramatic departure from Gompertz-type mortality dynamics
at older ages is not an artifact of declining density in Drosophila.
