Mixis strategies and resting eeg production of rotifers living in temporally-varying habitats

Abstract

A dynamic model based on six differential equations has been developed to explore the control of mixis of rotifers living in temporally-varying habitats. The equations give variation rates of amictic females, three stages of mictic females, males and resting eggs. The model takes into account some constraints on mixis (e.g., male-female encounter probability and effort involved in resting egg production) and its predictions have been generated by computer simulation using parameter values from the literature. For simulation, a time-dependent birth rate function was assumed to account for changes in the environment, and several mixis patterns (i.e., moment of mixis induction and mictic rate if induced) were presumed, followed by computing resting egg production. The results were very insensitive to changes in those model parameters associated with mixis; however, several assumptions could quantitatively affect the conclusions.When compared with the results reported in the literature, results from our simulations suggest that the optimal mixis strategy could be very dependent on the ecological features of the habitat. Moreover, in temporal habitats high mictic rates should be expected when the mixis is induced, and the optimal moment of mixis induction would be few days before the mortality rate overcompensates the birth rate of amictic females. Furthermore, the optimal strategy could be affected by informational constraints, and some degree of variability in the moment of mixis induction, whether or not genetically determined, could be maintained in the population.