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dr hab. Mariusz Cichoń
cichon@eko.uj.edu.pl |
Dep. of Population Ecology Inst. of Environmental Sciences Jagiellonian University Gronostajowa 7, 30-387 Kraków Poland tel. + 48 12 664 52 01 fax + 48 12 664 69 12 |
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Cichoń M., Kozłowski J.
EVOL ECOL RES
2000; 2: 857-870
Abstract:
Aging is a general feature of higher organisms. Evolutionary theories of aging rest on a gradual decline of fitness sensitivity to changes in survival and fecundity with age, so traits expressed late in life are less favored by natural selection than those expressed early in life. From the life history perspective, aging may result from a scheme of optimal resource allocation in which investment in repair is lower than that required for removing all experienced damage. This paper reports the results of a dynamic programming model based on the disposable soma theory of aging, which optimizes resource allocation to growth, reproduction and repair. The optimal allocation strategy responds to the level of externally imposed mortality, and repair intensity varies with age, being the highest early in life, diminishing later, and stopping completely well before the end of the maximum expected life. Because the repair level varies, the aging rate is the highest under high extrinsic mortality and the lowest under low mortality. The allocation strategy shapes the survivorship curve and maximum lifespan. The model results provide an explanation of the variety of survivorship curves and maximum lifespans observed in nature. The results are discussed with empirical data from studies using mainly comparative approaches.
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