A Demographic Profile of the Fastest Growing Metazoan: A Strain of Brachionus calyciflorus (Rotifera)

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Abstract
Evidence shows that trade-offs between growth, reproduction and maintenance tend to maximize the maximum specific growth rate, .mu.max, of a population for a given environment. We tested this hypothesis with two rotifer (Brachionus calyciflorus Pallas) populations which differed with respect to their .mu.max. Through measurement of various demographic variables, we found that the population which had a higher .mu.max also possessed the following characteristics: 1) higher fecundity in younger age classes, 2) decreased life span, 3) decrease in egg production times, 4) a loss of sexuality, 5) a 24% decrease in adult body size and 6) a 71% decrease in egg volume. The results support the hypothesis of a trade-off between reproduction and growth-maintenance, whereby, production of energy stores is negatively correlated with increased .mu.max. The lower .mu.max observed in field-collected populations may result from the need to produce energy stores for patchy and variable environmental conditions.