caa a22 4500 469098732 CHVBK 20180323133039.0 cr unu---uuuuu 170328e19920701xx s 000 0 eng 10.1007/BF01875448 doi (NATIONALLICENCE)springer-10.1007/BF01875448 Energy allocation rules in Daphnia magna [Elektronische Daten] clonal and age differences in the effects of food limitation [Douglas Glazier, Peter Calow] Summary: The allocation of energy to carapace formation, respiration, growth, and reproduction were examined in two parthenogenetic clones ofDaphnia magna (Cladocera) cultured at two levels of food (Chlorella) concentration. Clonal differences in energy allocation were more apparent at high ration (1.5 μg C mL-1) than at low ration (0.3 μg C mL-1). These differences included respiratory and molting costs, and the timing of energy allocation to growth and reproduction. A comparison of active vs. anesthetized animals revealed that the interclonal difference in respiration rate was the result of a difference in activity level. In both clones mass-specific rates of respiration, growth, and brood production all decreased at low vs. high ration levels, whereas mass-specific molt-loss rate increased. Lowered food concentration decreased the relative allocation of energy to growth and reproduction, but increased allocation to maintenance (respiration and carapace formation). These allocation responses to food limitation indicated that for both clones the highest energy priority was carapace formation. However, the relative priority of respiration, growth and reproduction varied with age and clone. In juveniles (instars 1-4) the priority ranking of growth was essentially equal to that of respiration, whereas respiration always had higher priority in adults (instars 5-9). All three possibilities for the relative ranking of growth and reproduction (i.e., growth>reproduction, growth=reproduction, and reproduction>growth), as specified by different models in the literature, were observed depending on age and clone. The energy allocation rules were also shown to vary between other daphniid species. Furthermore, metabolic responses to chronic food limitation may be different from responses to acute food deprivation. In this study, one clone showed a greater decrease in respiration rate as a result of lifetime food limitation than did the other, but the opposite was true when these clones were exposed to 48 h of starvation. These differences in allocation rules and in acute vs. chronic responses may have to be considered when using physiological data to modelDaphnia populations. Springer-Verlag, 1992 Age nationallicence Clones nationallicence Daphnia nationallicence Energy allocation nationallicence Food concentration nationallicence Glazier Douglas Department of Animal and Plant Sciences, University of Sheffield, S10 2TN, Sheffield, UK aut Calow Peter Department of Animal and Plant Sciences, University of Sheffield, S10 2TN, Sheffield, UK aut Oecologia Springer-Verlag 90/4(1992-07-01), 540-549 0029-8549 90:4<540 1992 90 442 https://doi.org/10.1007/BF01875448 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF01875448 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Glazier Douglas Department of Animal and Plant Sciences, University of Sheffield, S10 2TN, Sheffield, UK aut NATIONALLICENCE 700 1- Calow Peter Department of Animal and Plant Sciences, University of Sheffield, S10 2TN, Sheffield, UK aut NATIONALLICENCE 773 0- Oecologia Springer-Verlag 90/4(1992-07-01), 540-549 0029-8549 90:4<540 1992 90 442 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer