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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ref ID : 118

Richard S. Stemberger; Food limitation, spination, and reproduction in Brachionus calyciflorus. Limnol.Oceanogr. 35(1):33-44, 1990

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The Brachionus calyciflorus polymorphism involves both a chemical secreted by the predatory rotifer Asplanchna and food concentration. Food concentration accounted for 30-37% of the explained variance in spine length in treatments containing Asplanchna factor. The longest spines developed only in low-food conditions containing the Asplanchna chemical, indicating that the factors were additive. Newborns exposed only to low concentrations of food during the first 3 day after hatching developed relatively long spines and smaller body sizes than their high-food-adapted mothers. The population growth rate of the Asplanchna-induced phenotype was significantly higher than that of the short-spined controls over a wide range of food concentrations (0.4-15.0 ug ml-1 dry mass of algae). Most importantly, elongated spines were associated with a reduced threshold food concentration for reproduction, suggesting that they return an energetic benefit exceeding their developmental and maintenance costs.