Institute of Biophysics, Siberian Branch of Russian Academy of Science, Akademgorodok, Krasnoyarsk 660036, Russia

Abstract

Combined influence of "water of aggregation" and food concentration on the reproductive parameters of Moina macrocopa females was investigated. In all experiments the influence of population density was associated with the effect of "water of aggregation" prepared earlier by keepin dense population (200 mg/ml) of M.macrocopa. It was shown that life-span of M.macrocopa females in "water of aggregation" was not dependent on food concentration; under conditions of all tested food concentration it was less than in case of control clean water. There was no difference in proportion of males produced in "water of aggregation" and in control though more males were born under conditions of higher food concentration. In general "water of aggregation" causes a specific acceleration of female life history: the life-span and the period between clutches decrease, the amount of neonates in last clutches increases while the chance of male production at the beginning of reproduction period becames greater. The "water of aggregation" could also causes the formation of ephipial eggs instead of the first partenogenetic clutch. It seems that life strategy under conditions of very high mortality associated with "water of aggregation" is aimed to maximum realization of individual capacities in short period of time.