Fig 1.
Steps are numbered in accordance with the text (a—f). V and A stand for fractions of R. variabilis and H. azureiventris, respectively. Structural formulas shown in (f) are only examples.
Fig 2.
Results of the preliminary trials to find a sorbent to extract the active tadpole compounds.
Ratio (in percent) of offspring depositions in clean water (grey narrow bars) and water used by tadpoles and treated with sorbents afterwards (black narrow bars). The expected distribution (50:50) is shown in lighter shades of grey in the background. V and A refer to R. variabilis and H. azureiventris, respectively. When frogs showed a significant preference for the clean water we assumed that the treated water still contained tadpole compounds, i.e. the sorbents did not filter them sufficiently out of the water to end the avoidance behavior. Only after the treatment with DSC-18 did frogs not show avoidance of tadpole-treated water. * p < 0.05, ** p < 0.01, *** p < 0.001.
Fig 3.
Bioassay results after offering the fractionated compounds of the tadpoles to the frogs.
The ratio of offspring depositions in clean water (grey narrow bars) and in water treated with chemically processed (A) R. variabilis and (B) H. azureiventris substances (black narrow bars) is shown in percent. V and A stand for R. variabilis and H. azureiventris, respectively. The distribution of the total samples (Vtotal and Atotal) is shown with lighter grey shades in the background. Connecting lines leading from results from 2012 to 2013 show which fractions were further processed in 2013 and contain identical compounds. * p < 0.05, ** p < 0.01, *** p < 0.001.
Table 1.
Pooled egg and tadpole depositions placed by parental Ranitomeya variabilis in cups with clean or treated water.
Table 2.
Compounds found in fractions avoided in the bioassays by Ranitomeya variabilis.