Natural selection and the evolution of asynchronous aging

Jacob A. Moorad, Sanjana Ravindran

Research output: Contribution to journalArticlepeer-review


Understanding within-population variation in aging rates across different phenotypic traits is a central focus of biogerontological studies. Early evolutionary models predict that natural selection acts to cause all traits to deteriorate simultaneously. However, observations of aging rates provide evidence for widespread patterns of asynchronous aging in laboratory and natural populations. Recent verbal models put forth to explain such observations argue that because senescence is costly to fitness, selection should cause phenotypic traits that are most important to fitness to senesce slower than traits that are less related to fitness. Here we show that formal evolutionary theory supports neither prediction. Instead, we find that selection will favour the evolution of the most rapid rates of aging in those traits that are under the strongest selection at early ages because selection for these traits erodes the fastest. This reinforces the expectation that natural selection should play a role in the evolution of among-trait variation in aging, but in a contradictory way to that suggested previously. We demonstrate how to quantify age-specific sources of selection for age-specific traits and how these estimates can be used to understand how well patterns of age-related changes in selection can explain observed patterns of among-trait variation in aging rates.
Original languageEnglish
JournalThe American Naturalist
Issue number4
Early online date18 Feb 2022
Publication statusPublished - 1 Apr 2022


  • selection
  • senescence
  • aging
  • mosaic
  • asynchrony
  • phenotype


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