V.N. Novoseltsev, R. Arking, J.R. Carey, J.A. Novoseltseva, A.I. Yashin

Reproduction is usually characterised by mean-population fecundity pattern. Such a pattern has a maximum at earlier ages and a gradual decline of egg production subsequently. We show that individual fecundity trajectory do not follow such a pattern. In particular, it has no maximum. The three-stage pattern, which includes maturation, maturity and reproductive senescence, is more appropriate description of individual fecundity. The mean-population maximum in fecundity rate arises as a by-product of averaging of "flat" individual fecundity patterns across the population.

We present here some data for Drosophila and Mediterranean fruit fly females that clearly confirm the above hypothesis. We use two sets of data. The first set is 500 controls of Drosophila (Ra strain) from a procedure of artificial selection for increased longevity and the second one is 1000 Medflies from a normal population. In both cases we demonstrate that a flat individual fecundity pattern exists having a constant-rate plateau, which is changed at some critical point by an exponential "senescent part". Such presentation is essential for studying of fly fecundity and longevity and, especially, in research on late life.

Keywords (Optional): 
individual fecundity pattern