An experimental test of the egg‐ratio method with instantaneous birth rate as an independent variable

The accuracy of three mathematical models that have been used to calculate instantaneous birth rate ( b ) from the ratio of eggs to females ( E ) in a population was determined with steady state populations of the rotifer Brachionus calycifllorus. Typically, b is calculated from E with these models. We were able to choose b as an independent variable, with the physical characteristics of our culture device (a two‐stage steady state chemostat), which also satisfied the major assumptions of the models. We then measured E and calculated b from E with the three models. The model of Paloheimo gave the best fit to these steady state data when the calculated b and observed b were compared.