Experimental Induction of the Production of Ephippia By Daphnia Magna Straus (Cladocera)

Abstract

EXPERIMENTAL INDUCTION OF THE PRODUCTION OF EPHIPPIA BY DAPHNIA MAGNA STRAUS (CLADOCERA) BY H. C. BUNNER and K. HALCROW Division of Science and Mathematics, University of New Brunswick, Saint John, N.B., Canada INTRODUCTION The ability of natural and laboratory populations of the cladoceran genus Daphnia to reproduce either parthenogenetically or by sexual means, the latter accompanied by the formation of dormant eggs enclosed within a thickened, pigmented portion of the brood chamber, the ephippium, has long been recognized, and the identity of the factors, extrinsic and/or intrinsic, responsible for the shift from one form of reproduction to the other has