Abstract
While most theoretical models for the evolution of ageing assume that duration of pre-adult development does not affect the longevity, experimental data are still controversial and inconsistent. Here we examined the short-term and long-term pattern of pre-adult development time and longevity in populations of the gypsy moth (Lymantria dispar) originating from either oak forest (Quercus petrea), a suitable, or locust-tree forest (Robinia psedoacacia), a poor habitat. Using a full-sib design, we examined the genetic correlations between traits found in larvae reared on oak or locust-tree leaves. We detected only negative and insignificant genetic correlations, except for males from the Robinia population reared on oak leaves where the correlation was negative and sig- nificant. Our results also showed that a population living 40 generations in the locust-tree forest exhibited a significantly higher lon- gevity than the Quercus population, whereas a significant difference between these two populations in pre-adult development time does not exist. The results are discussed in relation to the potential effect of stress selection in moulding the longevity of the gypsy moth.
Highlights
Most contemporary theoretical models for the evolution of ageing assume that duration of pre-adult development does not affect the longevity
Pre-adult development time remains longer and the lifespan of females and males shorter on the locust-tree on the oak leaves, it appears that the gypsy moth population living 40 generations in the locust-tree forest has experienced selection for fast preadult development and longer adult life (Figs 1 and 2)
Since the significant population × host interactions for fitness related traits are thought to be statistical evidence for the presence of population-level host plant specialization, it appears that trophic adaptation in the Robinia population, through shortening of development time of the gypsy moth on a poor host, is not yet fully evolved
Summary
Most contemporary theoretical models for the evolution of ageing assume that duration of pre-adult development does not affect the longevity (reviewed in Finch, 1990; Rose, 1991; Charlesworth, 1994). There are still advocates (e.g. Lints, 1988) of the developmental theory of ageing which postulates that, in holometabolous insects, pre-adult development time and lifespan are causally related. According to this hypothesis species-specific ageing and longevity themselves require no evolutionary explanation because they are the components of normal development. Experimental support for this hypothesis was thought to come from studies devoted to the analyses of environmentally induced changes of pre-adult development and adult longevity. Starvation of caterpillars slowed larval development (about 50%) without altering the duration of the adult period (Kopec, 1924)
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