Statistical tests of demographic heterogeneity theories

Abstract

In this paper we develop predictions from models of life-long demographic heterogeneity. These predictions are then compared to observations of mortality in large laboratory populations of Drosophila melanogaster. We find that the demographic heterogeneity models either require levels of variation that far exceed what would be considered biologically plausible, or they predict a much larger number of very old individuals than we actually observe. We conclude that the demographic heterogeneity models are not reasonable explanations of demographic patterns and are weakly motivated biological models.

Demographic heterogeneity explains age-specific patterns of genetic variance in mortality rates

“…1(a)), or only within-line heterogeneity ( Fig. 1(b)), the among-line variation in lnðmðxÞÞ is due to binomial sampling effects (Mueller et al, 2003). Amongline (genetic) demographic heterogeneity (Figs.…”

“…For example, it is possible that the decline in genetic variance of lnðmðxÞÞ at intermediate ages does reflect some intrinsic biological factor or aspect of natural selection that results in different genotypes having similar mortality rates. Mueller et al (2003) advocate this latter position, and have attempted to advance it by attacking heterogeneity theory. However, their analysis is flawed.…”

“…That usage will be continued here, except that it is also understood that the among-line variation in mortality rates contains a component due to the stochasticity of mortality within lines. This latter source of variation is binomial (or mixed binomial) sampling (Mueller et al, 2003).…”

“…Following the earlier papers (Service, 2000a;Mueller et al, 2003), each simulation included 24 cohorts (lines), and each cohort comprised 1250 individuals. There were 10 replicate simulations for each analysis.…”

The Quest for Immortality in Triatomines: A Meta-Analysis of the Senescence Process in Hemimetabolous Hematophagous Insects

“…The older remaining individuals from the cohort are expected to be much more robust so that the mortality rate becomes a very shallow function of age, resembling a plateau. However this demographic heterogeneity model does not seem to be a reasonable explanation of demographic patterns and it has only a weak biological basis (Mueller et al, 2003).…”