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vol. 156, no. 1 the american naturalist july 2000 Heterogeneity in Individual Mortality Risk and Its Importance
 

Summary: vol. 156, no. 1 the american naturalist july 2000
Heterogeneity in Individual Mortality Risk and Its Importance
for Evolutionary Studies of Senescence
Philip M. Service*
Department of Biological Sciences, Northern Arizona University,
Flagstaff, Arizona 86011
Submitted August 6, 1999; Accepted March 1, 2000
abstract: Mortality was simulated under the assumption of het-
erogeneity in individual age-specific mortality risk. Heterogeneitywas
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 Drosophilamelanogaster.
Simulations of large cohorts reproduced mortality plateaus 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-ge-
notype heterogeneity in mortality risk resulted in a decline in genetic
variance of mortality rates at old ages. That result suggests that the

  

Source: Allan, Gery - Department of Biological Sciences, Northern Arizona University

 

Collections: Biology and Medicine; Environmental Sciences and Ecology