Patterns of physiological decline due to age and selection in Drosophila melanogaster.
In outbred sexually reproducing populations, age-specific mortality rates reach a plateau in late life following the exponential increase in mortality rates that marks aging. Little is known about what happens to physiology when cohorts transition from aging to late life. We measured age-specific values for starvation resistance, desiccation resistance, time-in-motion, and geotaxis in ten Drosophila melanogaster populations: five populations selected for rapid development and five control populations. Adulthood was divided into two stages, the aging phase and the late-life phase according to demographic data. Consistent with previous studies, we found that populations selected for rapid development entered the late-life phase at an earlier age than the controls. Age-specific rates of change for all physiological phenotypes showed differences between the aging phase and the late-life phase. This result suggests that late life is physiologically distinct from aging. The ages of transitions in physiological characteristics from aging to late life statistically match the age at which the demographic transition from aging to late life occurs, in all cases but one. These experimental results support evolutionary theories of late life that depend on patterns of decline and stabilization in the forces of natural selection.
Department of Ecology and Evolutionary Biology, University of California Irvine, Irvine, California, 92697. pshahrestani@fullerton.edu.|Department of Biological Science, California State University Fullerton, Fullerton, California, 92831. pshahrestani@fullerton.edu.
Parvin
P
Shahrestani
Department of Biological Science, California State University Fullerton, Fullerton, California, 92831.
Julian B
JB
Wilson
Department of Ecology and Evolutionary Biology, University of California Irvine, Irvine, California, 92697.
Laurence D
LD
Mueller
Department of Ecology and Evolutionary Biology, University of California Irvine, Irvine, California, 92697.
Michael R
MR
Rose
D000375:Aging / Q000235:genetics* / Q000502:physiology; D000818:Animals; D004331:Drosophila melanogaster / Q000235:genetics* / Q000254:growth & development; D019143:Evolution, Molecular; D010641:Phenotype; D012641:Selection, Genetic
Aging; Drosophila; age-specific physiology; experimental evolution; late life