Laboratory Evolution of Life-History Traits in the Bean Weevil (Acanthoscelides obtectus): The Effects of Selection on Developmental Time in Populations with Different Previous History

Abstract

In this study we examined the direct and correlated responses for fast and slow preadult development time in three laboratory populations of the bean weevil (Acanthoscelides obtectus). The first population ("base," B) has experienced laboratory conditions for more than 10 years; the second ("young," Y) and the third ("old," 0) populations were selected for early and late reproduction, respectively, before the onset of the present experiments. All three populations are successfully selected for both fast and slow preadult development. The realized heritabilities are very similar in all populations, suggesting a similar level of the additive genetic variance for preadult development. We studied the correlated responses on the following life-history traits: egg-to-adult viability, wet body weight, early fecundity, late fecundity, total realized female fecundity, and adult longevity. All life-history traits examined here, except for the egg-to-adult viability, are affected by selection for preadult development in at least in one of the studied populations. In all three populations, beetles selected for slow preadult development are heavier and live longer than those from the fast-selected lines. The findings with respect to adult longevity are unexpected, because the control Y and 0 populations, selected for short-and long-lived beetles, respectively, do not show significant differences in preadult development. Thus, our results indicate that some kind of asymmetrical correlated responses occur for preadult development and adult longevity each time that direct selection has been imposed on one or the other of these two traits. In contrast to studies with Drosophila, it appears that for insect species that are aphagous as adults, selection for preadult development entails selection for alleles that also change the adult longevity, but that age-specificselection (applied in the Y and 0 populations) mostly affects the alleles that have no significant influence on the preadult development. Implications of these findings on the developmental and evolutionary theories of aging are also discussed.

Ageing and the evolution of female resistance to remating in seed beetles

“…This was supported by the post hoc tests (see table 2 and figure 1), that identified a significant increase in female remating rate with age in the Early lines and a significant, although less marked, decrease in remating rate with age in the Late lines. (Tucic et al 1996(Tucic et al , 1998. In essence, our results thus show that female resistance to remating decreases with age when selection late in life is absent and increases with age when selection late in life is intense.…”

Realized correlated responses to artificial selection on pre-adult life-history traits in a butterfly

“…not corrected for body size; Fischer et al, 2006). Thus, it seems that selection on body size does yield a correlated response in egg size (Tables 1 and 3; Fischer et al, 2002), whereas the opposite trend is fairly weak (see also Tucic et al, 1998). Thus, correlated responses in life-history traits were frequently not consistent with expectations and were, overall, rather unpredictable (cf.…”

Egg-dumping behaviour in the seed beetle Acanthoscelides obtectus (Coleoptera: Chrysomelidae: Bruchinae) selected for early and late reproduction

“…In addition, the trade-off recorded in the selection for dumping behaviour may also be attributable to linkage disequilibrium between the genes that affect pre-adult developmental time and those that affect longevity. Therefore, it is almost impossible to generalize about the genetic correlations between traits, except by selecting for one trait and recording the response in the other and vice versa (Tuci et al, 1998). In the present study we test whether selection for altering the age at physiological maturity, which directly favours short-or long-lived females, results in the changes in egg-dumping behaviour predicted by Messina et al (2007).…”

“…In the E selection regime, offspring were recruited to the next generations during the first two days of adult life, whereas in the L selection regime, the recruitment occurred from day 10 until death. Previous studies indicate that relative to the E lines the L lines have a reduced early fecundity, increased body weight, elevated late life fecundity and prolonged life-span (Tuci et al, 1997(Tuci et al, , 1998. It is important to note that in the L lines the period between eclosion and the onset of oviposition is longer than in the E lines (Tuci et al, 2004), indicating that the traits under selection coincide with the age of female's physiological maturity.…”