Male to hermaphrodite sex change in gametophytes of the fern Ceratopteris richardii is affected by hermaphrodite density, male age, and male size

Abstract

Gametophytes of the fern Ceratopteris richardii are male or hermaphrodite. The presence of hermaphrodite-secreted antheridiogen influences gametophytes to develop as male (induction), while its absence leads to hermaphrodite development. Males require the continued presence of antheridiogen to remain male. Removal of males from antheridiogen leads to sex change (conversion) of males to hermaphrodites.Density of hermaphrodites that males were exposed to and amount of time males were exposed to antheridiogen was experimentally manipulated to determine if conversion time was affected. Analysis of covariance was employed with male size serving as a covariate.Results suggest that males continuously sample the neighborhood for information regarding the density of hermaphrodites by perceiving hermaphrodite-secreted antheridiogen and use this information to determine whether to convert to hermaphrodite. Larger males converted faster than smaller males suggesting a potential for smaller males to remain male once larger males convert. Conversion time was longer in males grown in higher densities of hermaphrodites and shorter in males exposed to antheridiogen for a longer time, suggesting that males increase sensitivity to antheridiogen with higher doses but decrease sensitivity as they age. It is thought that such decision making is important for C. richardii populations to maintain beneficial sex ratios.