However, in Mating II, restricted-diet animals had decreased fitness in the recipient role as a result of their reduced egg output.
When food was plentiful, animals assumed both sperm donor and recipient roles at relatively even frequency.
Recipient roles, by contrast, are expected to have a more linear relationship between fitness gains and investment (Vizoso and Scharer, 2007).
Animals did not consistently alternate between sperm donor and recipient roles over multiple days.