Ref ID : 6923
Eduardo M. Garcia-Roger, Natalia Dias, Maria Jose Carmona, and Manuel Serra; Crossed induction of sex in sympatric congeneric rotifer populations. Limnol.Oceanogr. 54(6):1845-1854, 2009
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The transition from asexual to sexual reproduction in rotifers of the genus Brachionus (Monogononta) is triggered by a chemical signal produced and released by the rotifers themselves; the signal accumulates in the environment as population density increases. The response to this signal has been hypothesized to be species-specific. If not, the timing of sex and final diapausing egg production of a species might not be optimized. In this study, a set of experiments-based on individual and mass culture approaches- was carried out to investigate the differentiation in sex induction signals between sympatric and allopatric congeneric Brachionus populations by analyzing the capability of the medium conditioned by the growth of a population (i.e., medium containing the inducing signal) to induce sex in a different one. We found that populations induce sex in response to medium conditioned by congeneric populations. Results suggest differences among species in their production and responsiveness to sex-inducing signals, as well as slight differentiation in these signals. The observed lack of strong differentiation between sympatric populations is proposed to have implications in avoidance of competition.