Results
As expected, most individuals of P. vaillanti and P. bicolor remained within 5 cm of the water column the majority of the time (Figure 2). Interestingly, the smaller individuals of P. bicolor were more evenly distributed along the water column, yet we were unable to obtain data from medium or small larvae of the former species. Both Phyllomedusa species were significantly more conspicuous against the water background, compared C. tomopterna(Figure 3). In turn, P. vaillanti was more conspicuous thanP. bicolor , particularly concerning the frontal metallic patch (Figure 3). Conspicuousness was higher in larger larvae of the most conspicuous species, P. vaillanti (linear regression: F=24.69, p=<0.001, R2=0.13, N=193) but this relationship was absent in the other two species (Figure 3).
Dragonfly naiads preyed upon 73% of the tested frog larvae, and we detected no significant differences in the vulnerability of the three species of tadpoles (X2=0.102, df= 2, p= 0.94 (Figure 4-A) Nevertheless, seven out of the 13 naiads (54%) that preyed uponP. vaillanti died within 4 h, whereas none of them died after consuming P. bicolor or C. tomopterna larvae (Figure 4-B). We also found evidence of larvae toxicity for the tested vertebrate. The tadpole skins of P. bicolor and P. vaillanti significantly affected mice behavior: and eliciting spasms, lethargy, and decreased movement throughout the arena. In contrast, the mice injected with skin extracts of C. tomopterna were indistinguishable in behavior from the mice injected with saline solution (Figure 5). Regarding body size, we found no evidence supporting a relationship between larval size and palatability (F = 0.60, p = 0.54, N = 38), or larval size and toxicity (F = 1.86, p = 0.11, N = 76) in any of the frog species we studied.
At the species level, some relationship between toxicity and conspicuousness was apparent: the non-toxic species (C. tomopterna ) was the less conspicuous as well. And the twoPhyllomedusa species differed in conspicuousness but were comparable in toxicity at least for our study system (Figure 5). At the individual level, however, only the tadpoles of P. vaillantishowed a positive relationship between toxicity and the conspicuous of the front patch (Figure 6).