Lifespan of a Ceratitis fruit fly increases with higher altitude

Abstract

Variation in lifespan may be linked to geographic factors. Although latitudinal variation in lifespan has been studied for a number of species, altitude variation has received much less attention, particularly in insects. We measured the lifespan of different populations of the Natal fruit fly, Ceratitis rosa, along an altitudinal cline. For the different populations, we first measured the residual longevity of wild flies by captive cohort approach and compared the F1 generation from the same populations. We showed an increase in lifespan with higher altitude for a part of the data obtained. For the field-collected flies (F0) the average remaining lifespan increased monotonically with altitude for males but not for females. For the F1 generation, the longevity of both males and females of the highest-altitude population was longer than for the two other lower-altitude populations. This relationship between altitude and lifespan may be explained by the effects of temperature on reproduction. Reproductive schedules in insects are linked to temperature: lower temperature, which is characteristic of high-altitude sites, generally slows down reproduction. Because of a strong trade-off between reproduction and longevity, we therefore observed a longer lifespan for the high-altitude populations. Other hypotheses, such as different predation rates in the different sites, are also discussed. © 2010 The Linnean Society of London.