A female rotifer (Brachionus calyciflorus) with two eggs. The eggs are the result of parthenogenesis, or asexual reproduction by the female, which occurs in rotifers when growing conditions are favorable. Populations of this rotifer species, which can be maintained in a laboratory on a food source of algae, are an ideal model system for testing ecological theory in microcosms. Replicate populations of this species can be brought into synchrony either by the frequent dispersal of a small number of individuals from one population to another or by varying their food. This photograph originally appeared on the cover of Ecology (86:6) in June of 2005.