Risk reduction strategies in Branchipus schaefferi (Crustacea: Anostraca: Branchiopoda) as adaptation to a variable environment

Mud from a temporary pool in Morocco was sequentially inundated and dried at the laboratory to follow the life history of Branchipus schaefferi . Once adult, each female was coupled to a male in order to study their life history and reproduction. The average percentage of hatching decreased during the successive inundations, presumably as an adaptation to the unpredictability of the habitat. However, there was no indication that the offspring of the first inundation would preferentially hatch during their first inundation too, neither was there any such preference in the offspring of the delayed hatchings. Each female reduced risk by spreading hatching time of her resting eggs over consecutive inundations. Eggs did not hatch all at the same moment, reducing the chance that a female’s entire offspring would die before reaching maturity if the pool would dry out too soon. There was a significant difference between the mean value of the number of resting eggs produced by the females from a large clutch size, and those produced by females from a small clutch size. There thus appears to be a genetic base for the clutch size of females.