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Heterogeneity in individual mortality risk and its importance for evolutionary studies of senescence

Service, P.M. (2000) Heterogeneity in individual mortality risk and its importance for evolutionary studies of senescence. American Naturalist, 156 (1). pp. 1-13. ISSN 1537-5323


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Publisher’s or external URL: http://dx.doi.org/10.1086/303371


Mortality was simulated under the assumption of heterogeneity in individual age-specific mortality risk. Heterogeneity was modeled by assigning each individual its own Gompertz mortality function. Means and variances of the Gompertz intercept and slope parameters were based on published data for Drosophila melanogaster. Simulations of large cohorts reproduced mortality plateaux similar to those observed for actual cohorts of flies. Catastrophic late-age mortality was not observed except when heterogeneity was very low and rates of senescence were very high. A second set of simulations was designed to mimic experiments that have investigated age-specific patterns of genetic variance in mortality rates. Within-genotype heterogeneity in mortality risk resulted in a decline in genetic variance of mortality rates at old ages. That result suggests that the decline in genetic variance at old ages that has been observed in some experiments is an artifact of heterogeneity. Mortality rate plateaux, decrease in genetic variance of mortality rates at old ages, and absence of catastrophic late-age mortality all appear to contradict predictions of the evolutionary theory of senescence. Heterogeneity in mortality risk may explain those contradictions.

Item Type: Article
Publisher’s Statement: © 2000. The University of Chicago Press.
ID number or DOI: 10.1086/303371
Keywords: age-specific mortality; Animals; arthropods; death rate; Diptera; Drosophila; Drosophila melanogaster; drosophila-melanogaster; Drosophilidae; egg-production; eukaryotes; Evolution; frailty; Genetics and Molecular Genetics (Wild Animals) (YY300) (New March 2000); genetic variance; gompertz function; Hexapoda; INSECTS; Invertebrates; Longevity; models; mortality; mortality rate; Plant Pests (FF620) (New March 2000); PLATEAUS; POPULATION; quantitative genetics; RATES; selection; senescence; Taxonomy and Evolution (ZZ380)
Subjects: Q Science > QH Natural history > QH301 Biology
Q Science > QP Physiology
NAU Depositing Author Academic Status: Faculty/Staff
Department/Unit: College of Engineering, Forestry, and Natural Science > Biological Sciences
Date Deposited: 30 Sep 2015 05:27
URI: http://openknowledge.nau.edu/id/eprint/317

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