Note
The thermal demographic advantage ofvertical migration was tested using life-table studies of Daphnia parvula cohorts fed on Chlamydomonas reinhardi. At a high food level, lifespan and body size at death were relatively insensitive to temperature differences. Fecundity parameters (brood size, brood number, total number of young per reproductive female, and net reproduction rate) were highest at an optimal midrange temperature (15°C). However, age at onset of reproduction, instar at first reproduction and brood duration decreased with increasing temperature, resulting in an overall increase in the realized rate of increase (r) with increasing temperature.