Anti-Predator Defenses in Daphnia: Are Life-History Changes Always Linked to Induced Neck Spines?

Abstract

The cladoceran Daphnia pulex responds phenotypically to chemicals released by one of its invertebrate predators Chaoborus flavicans. They produce neck spines with often several teeth which possibly increase the chance to survive the predator's attacks. On the other hand, these spined animals suffer a reduced fitness in terms of delayed maturity and reduced fecundity. Several studies describe both neck teeth and life-history responses as trade-offs which are directly linked although there is no direct evidence that neck teeth themselves bear those life-history costs. One possible way of testing the connection between morphology and life-history shifts is described in this study