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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ref ID : 2750

John J. Gilbert; Polymorphism and sexuality in the rotifer Asplanchna, with special reference to the effects of prey-type and clonal variation. Arch.Hydrobiol. 75(4):442-483, 1975

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The responses of two clones of A. sieboldi to alpha-tocopherol and different prey-types are compared. The campanulate morphotype may be induced by a variety of prey, algal and animal, and is not dependent on cannibalism. Sexuality is morphotype-dependent and is not directly controlled by the diet. Typically, saccate and campanulate females are amictic and asexual while a proportion of cruciform females is mictic and sexual. Body size in these morphotypes and in A. brightwelli is often directly related to prey size. Cruciforms may be as large as companulates. In one clone of A. sieboldi and in A. brightwelli amictic females are larger than mictic females. Body wall outgrowths are proportionately largest in young cruciforms. In both clones of A. sieboldi every saccate individual can produce cruciform offspring. These two clones differ greatly in their sensitivity to alpha-tocopherol, in the magnitude of their maximal body-wall-outgrowth response, and in their ability to express the campanulate morphotype. The distribution of female morphotypes and the degree of sexual reproduction in natural populations of A. sieboldi will depend on the diet, on factors influencing responses to the diet, and on the clones or genotypes of the individuals.