AGE-SPECIFIC PATTERNS OF GENETIC VARIANCE IN DROSOPHILA-MELANOGASTER .2. FECUNDITY AND ITS GENETIC COVARIANCE WITH AGE-SPECIFIC MORTALITY

Under the mutation accumulation model of senescence, it was predicted that the additive genetic variance (V-A) for fitness traits will incre ase with age. We measured age-specific mortality and fecundity from 65 ,134 Drosophila melanogaster and estimated genetic variance components , based on reciprocal crosses of extracted second chromosome lines. El sewhere we report the results for mortality. Here, for fecundity, we r eport a bimodal pattern for V-A with peaks at 3 days and at 17-31 days . Under the antagonistic pleiotropy model of senescence, it was predic ted that negative correlations will exist between early and late life history traits. For fecundity itself we find positive genetic correlat ions among age classes >3 days but negative nonsignificant correlation s between fecundity at 3 days and at older age classes. For fecundity vs. age-specific mortality, we find positive fitness correlations (neg ative genetic correlations) among the traits at all ages >3 days but a negative fitness correlation between fecundity at 3 days and mortalit y at the oldest ages (positive genetic correlations). For age-specific mortality itself we find overwhelmingly positive genetic correlations among all age classes. The data suggest that mutation accumulation ma y be a major source of standing genetic variance for senescence.