Laboratory evolution of longevity in the bean weevil (Acanthoscelides obtectus)

In this study we examined the effects of long-term selection on early and late reproduction in the bean weevil. The pure lines and the hybrids between the lines within a selection regime were compared for longevity, early and late female fecundity, male mating ability, pre-adult developmental time and wet adult weight. Comparison of hybrid with pure lines provided some evidence for inbreeding despression in the lines from both selection regimes. We found that virgin and mated adults of both sexes from the ''old'' lines lived longer than ''young'' line beetles. Comparisons of the hybrid ''young'' with hybrid ''old'' lines revealed a trade-off between early and late fecundity of females. For noncompetitive mating ability of males there was no difference between the lines with different rates of senescence when the males were young. But, when the males were older, beetles from the lines selected for delayed senescence expressed superior mating ability. In addition, the ''old'' line beetles take longer to develop and are heavier than those from ''young'' line beetles. Although these data suggest that shorter pre-adult developmental time may imply more rapid senescence, there is the possibility of inadvertent selection for rapid development in the ''young'' lines and this complicates the interpretation of the observed trade-off between the pre-adult and adult performances.