title: Aging, fertility, and immortality.
abstract: Evolutionary theory suggests that fecundity rates will plateau late in life in the same fashion as mortality rates. We demonstrate that late-life plateaus arise for fecundity in Drosophila melanogaster. The result qualitatively fits the evolutionary theory of late life based on the force of natural selection. But there are a number of alternative interpretations. Fecundity plateaus could be secondary consequences of mortality-rate plateaus. Female fecundity plateaus might arise from diminished male sexual function. Another alternative hypothesis is analogous to male sexual inadequacy: nutritional shortfalls. These may arise later in life because of a decline in female feeding or digestion. If some females have a life-long tendency to lay eggs at a faster rate, but die earlier, then aging for fecundity could arise from the progressive loss of the fast-layers, with the late-life plateau simply the laying patterns of individual females who were slow-layers throughout adult life. If this type of model is generally applicable to late life, then we should find that the females who survive to lay at a slow but steady rate in late life have a similar laying pattern in mid-life.
authors.affiliation: Department of Ecology and Evolutionary Biology, University of California, 321 Steinhaus, Irvine, CA 92697-2525, USA.
authors.forename: Casandra L
authors.initials: CL
authors.lastname: Rauser
authors.forename: Laurence D
authors.initials: LD
authors.lastname: Mueller
authors.forename: Michael R
authors.initials: MR
authors.lastname: Rose
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D005075:Biological Evolution; D004331:Drosophila melanogaster / Q000502:physiology*; D005260:Female; D005298:Fertility / Q000502:physiology; D008297:Male; D008954:Models, Biological