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

The life histories of holo-anhydrobiotic animals differ from those of all other organisms by a regular or irregular entrance into an ametabolic state induced by desiccation. Such ametabolic periods will arrest growth and reproduction completely and thus affect primary life history parameters dramatically. The selective forces and the genetic and physiological trade-offs acting on anhydrobiotic animals are to a large extent unknown. Assuming low growth rates and low juvenile to adult survival, general theoretical models on life history responses to stress predict that anhydrobiotic animals will be selected for a high degree of iteroparity, with low fecundity, large egg size, and low total reproductive investment. A high degree of variability in growth and reproduction should create a selective force in the same direction. Although basic empirical data on life history parameters are very scarce, available observations seem to be consistent with this prediction.