The Evolution of Life Histories in Holo-anhydrobiotic Animals: A First Approach

The life histories of holo-anhydrobiotic animals differ fromthose of all other organisms by a regular or irregular entranceinto an ametabolic state induced by desiccation. Such ametabolicperiods will arrest growth and reproduction completely and thusaffect primary life history parameters dramatically. The selectiveforces and the genetic and physiological trade-offs acting onanhydrobiotic animals are to a large extent unknown. Assuminglow growth rates and low juvenile to adult survival, generaltheoretical models on life history responses to stress predictthat anhydrobiotic animals will be selected for a high degreeof iteroparity, with low fecundity, large egg size, and lowtotal reproductive investment. A high degree of variabilityin growth and reproduction should create a selective force inthe same direction. Although basic empirical data on life historyparameters are very scarce, available observations seem to beconsistent with this prediction.