2006 The Society for the Study of Evolution. All rights reserved.
Evolution, 60(10), 2006, pp. 20812086
WITHIN-POPULATION VARIATION IN CYTOPLASMIC GENES AFFECTS FEMALE
LIFE SPAN AND AGING IN DROSOPHILA MELANOGASTER
ALEXEI A. MAKLAKOV,1,2 URBAN FRIBERG,1,3 DAMIAN K. DOWLING1 AND GO¨ RAN ARNQVIST1
1Animal Ecology, Department of Ecology and Evolution, Evolutionary Biology Centre, Uppsala University,
Norbyva¨gen 18D, SE 752 36 Uppsala, Sweden
3Department of Ecology and Environmental Science, Umea° University, SE 901 87 Umea°, Sweden
Abstract. It has been suggested that mitochondrial DNA (mtDNA) may play an important role in aging. Yet, few
empirical studies have tested this hypothesis, partly because the degree of sequence polymorphism in mtDNA is
assumed to be low. However, low sequence variation may not necessarily translate into low phenotypic variation.
Here, we report an experiment that tests whether there is within-population variation in cytoplasmic genes for female
longevity and senescence. To achieve this, we randomly selected 25 ``mitochondrial founders'' from a single, panmictic
population of Drosophila melanogaster and used these founders to generate distinct ``mt'' lines in which we controlled
for the nuclear background by successive backcrossing. Potential confounding effects of cytoplasmically transmitted
bacteria were eliminated by tetracycline treatment. The mt lines were then assayed for differences in longevity,
Gompertz intercept (frailty), and demographic rate of change in mortality with age (rate-of-senescence) in females.
We found significant cytoplasmic effects on all three variables. This provides evidence that genetic variation in