Ref ID : 2952
John J. Gilbert and James R. Litton, Jr.; Sexual Reproduction in the Rotifer Asplanchna girodi: Effects of Tocopherol and Population Density. J.Exp.Zool. 204(1):113-121, 1978
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Populations containing undetectable levels of tocopherol (<6.78-20.83 ng per g dry weight rotifer) exhibited normal sexual reproduction, indicating that this species and probably also A. brightwelli and A. sieboldi, do not require tocopherol for male fertility. Thus, the hypothesis that tocopherol is an adaptive signal for mictic-female production in these latter two species by virtue of its role in male fertility is no longer tenable. Dietary tocopherol had irregular and only slight, if any, effects on body size and shape, and it did not influence the level of mictic-female production. Mictic-female production was significantly but irregularly affected by population density, at least within the range of 0.0067 to 5 females per ml. No relationship between population density and level of mictic-female production was observed. The laboratory results are compared with available data on the occurrence of sexuality in a natural population. None of the 4,537 offspring isolated from parental females in the population density experiments were amphoteric females. Thus, at least under those conditions, this type of female must be extremely rare. A. girodi differs greatly from A. brightwelli and A. sieboldi regarding responses to tocopherol and the control of sexual reproduction.