S. Plaistow et Mt. Siva-jothy, The ontogenetic switch between odonate life history stages: effects on fitness when time and food are limited, ANIM BEHAV, 58, 1999, pp. 659-667
During the course of ontogeny, odonates switch from being aquatic larvae to
being terrestrial adults. Ontogenetic niche shift theory proposes that suc
h shifts are adaptive and have evolved to maximize a growth rate (size) to
mortality rate ratio. Individuals should therefore switch from one niche to
the other at an optimal size or state. Since the majority of odonates are
seasonal breeders, the extent to which the switch is optimal will depend up
on the time and the resources available during postembryonic development. W
e collected a cohort of larvae that varied in how close they were to eclosi
on and reared them on either a high-nutrition or a low-nutrition diet. We t
hen determined the relative influence of both time and nutritional constrai
nts on survival and development rate, as well as the body size, size-correc
ted flight muscle mass and fat reserves of individuals at eclosion. Damself
lies in both high- and low-nutrition treatments responded to a short develo
pment period by developing faster and reducing their body size, but did not
change their proportional investment in fat reserves and flight muscle. Re
duced larval nutrition resulted in decreased body size, flight muscle mass
and fat reserves at eclosion. However, it had no effect on survival to eclo
sion, or development rate. We discuss these results in terms of the influen
ce that time and nutritional constraints have on odonate development patter
ns and fitness. (C) 1999 The Association for the Study of Animal Behaviour.