TY - JOUR A1 - Fussmann, Gregor F. A1 - Weithoff, Guntram A1 - Yoshida, Takehito T1 - A direct, experimental test of resource versus consumer dependence : reply Y1 - 2007 UR - http://esapubs.org/esapubs/journals/ecology.htm U6 - https://doi.org/10.1890/06-1692 SN - 0012-9658 ER - TY - JOUR A1 - Boëchat, Iola G. A1 - Weithoff, Guntram A1 - Krüger, Angela A1 - Gücker, Björn A1 - Adrian, Rita T1 - A biochemical explanation for the success of the mixotrophy in the flagellate Ochromonas sp. N2 - We report the influence of different nutritional modes-autotrophy, mixotrophy, and heterotrophy-on the fatty acid and sterol composition of the freshwater flagellate Ochromonas sp. and discuss the ecological significance of our results with respect to the resource competition theory (rct). Polyunsaturated fatty acids (PUFAs) are the most efficient biochemical variable distinguishing between nutritional modes of Ochromonas sp. Decreasing concentrations of PUFAs were observed in the order autotrophs, mixotrophs, heterotrophs. In mixotrophs and heterotrophs, concentrations of saturated fatty acids were higher than those of monounsaturated fatty acids and PUFAs as a result of bacterivory. Stigmasterol was the main sterol in Ochromonas sp., regardless of nutritional mode. Mixotrophs showed higher growth rates than heterotrophs, which could not be explained by rct. Heterotrophs, in turn, exhibited higher growth rates than autotrophs, which were cultured under the same light conditions as mixotrophs. Mixotrophs can synthesize PUFAs, which are important for many physiological functions such as membrane permeability and growth. Thus, mixotrophy facilitated efficient growth as well as the ability to synthesize complex and essential biomolecules. These strong synergetic effects are due to the combination of biochemical benefits of heterotrophic and autotrophic metabolic pathways and cannot be predicted by rct. Y1 - 2007 UR - http://www.aslo.org/lo/ U6 - https://doi.org/10.4319/lo.2007.52.4.1624 SN - 0024-3590 ER - TY - BOOK A1 - Weithoff, Guntram T1 - Dietary restriction in two rotifers species : the effect of the length of food deprivation on life span and reproduction N2 - According to resource allocation theory, animals face a trade off between the allocation of resources into reproduction and into individual growth/maintenance. This trade off is reinforced when food conditions decline. It is well established in biological research that many animals increase their life span when food is in suboptimal supply for growth and/or reproduction. Such a situation of reduced food availability is called dietary restriction. An increase in life span under dietary restricted conditions is seen as a strategy to tolerate periods of food shortage so that the animals can start reproduction again when food is in greater supply. In this study, the effect of dietary restriction on life span and reproduction in two rotifer species, Cephalodella sp. and Elosa worallii, was investigated using life table experiments. The food concentration under dietary restricted conditions was below the threshold for population growth. It was (1) tested whether the rotifers start reproduction again after food replenishment, and (2) estimated whether the time scale of dietary restricted conditions is relevant for the persistence of a population in the field. Only E. worallii responded to dietary restriction with an increase in life span at the expense of reproduction. After replenishment of food, E. worallii started to reproduce again within I day. With an increase in the duration of dietary restricted conditions of up to 15 days, which is longer than the median life span of E. worallii under food saturation, the life span increased and the life time reproduction decreased. These results suggest that in a temporally (or spatially) variable environment, some rotifer populations can persist even during long periods of severe food deprivation. Y1 - 2007 UR - http://www.jstor.org/stable/40210866 U6 - https://doi.org/10.1007/s00442-007-0739-6 ER - TY - JOUR A1 - Weithoff, Guntram A1 - Wacker, Alexander T1 - The mode of nutrition of mixotrophic flagellates determines the food quality for their consumers Y1 - 2007 UR - http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2435.2007.01333.x/full U6 - https://doi.org/10.1111/j.1365-2435.2007.01333.x ER -