Description:
<jats:p>The study of 32 populations of <jats:italic>Arctodiaptomus bacillifer</jats:italic> and of 14 populations of <jats:italic>Acanthodiaptomus denticornis</jats:italic> has shown a good correlation between the body size of egg‐carrying females and the number of eggs actually carried by the same. Furthermore, these characters are correlated with the extent of the water renewal of each fake, based upon the ratio: area of drainage basin/area of lake. It is suggested that in any population, selection may favor females able to produce a number of eggs correlated with and balanced against the losses which outflowing waters induce in the pelagic stages of the population.</jats:p>