Cyclomorphosis in Bosmina and copepod predation

Abstract

In Pinks Lake, Quebec, individuals of the cladoceran Bosmina longirostris underwent an increase in mucro length during the summer at a time when adults of the predaceous copepod Epischura lacustris appeared. Predation experiments demonstrated that Bosmina with enlarged mucrones were less susceptible to Epischura predation than similar sized prey without the adaptation. The results support S. I. Dodson's hypothesis that cyclomorphosis is an adaptation against size-selective invertebrate predators.