Figure 1.
Morphological measurements taken on tadpoles and an example of sublethal predation.
(a) A tadpole of our study species, the red-eyed treefrog Agalychnis callidryas, shown with the five lateral morphological variables measured. Variables were total tadpole length (total tadpole length), body length (body length), body height (body height), tail muscle height (tail muscle height), and tail fin height (TFD). (b) An A. callidryas tadpole reared with fish that has a maimed tail and increased pigmentation.
Figure 2.
Hatching age and predator identity interact to affect tadpole tail fin height.
The specific combination of hatching age (early or late, solid and dashed lines respectively) and predator treatment (panels a–e) determined the allometric scaling relationship between body length and tail fin height in Agalychnis callidryas tadpoles. Black lines are regression fits from a linear mixed model for each predator-hatching combination. Grey lines in panels (b)–(e) are the regression fits from the control treatments (panel a) and are shown to increase ease of comparison.
Figure 3.
Predator identity affects tadpole tail muscle height.
Predator treatments influenced the allometric scaling relationship between body length and tail muscle height in Agalychnis callidryas tadpoles. Data are also shown for each hatching age treatment (early or late) although this did not significantly affect tail muscle height. Black lines are regression fits from a linear mixed model for each predator-hatching combination. Grey lines in panels (b)–(e) are the regression fits from the control treatments (panel a) and are shown to increase ease of comparison.
Table 1.
Results of linear mixed models testing for effects of predator treatment (control, water bug, dragonfly, or fish alone or all three predators together) and hatching age (4 or 6 days post-oviposition), while controlling for effects of body length, on Agalychnis callidryas tadpole tail fin height and tail muscle height.
Figure 4.
Tadpoles had darker pigmentation if raised with fish.
Relative Agalychnis callidryas body pigmentation for tadpoles raised in predator-free control tanks or in one of four predator treatments (dragonfly naiads, water bugs or fish alone or all three predators together). Tadpoles were significantly more pigmented in the two treatments containing fish. Relative pigmentation was defined as log (Area of pigmentation/total tadpole length).
Figure 5.
Tadpole swimming performance was affected by body size.
Agalychnis callidryas tadpole (a) swimming speed increased with body length, whereas (b) the number of beats per centimeter of distance swam decreased with body length. Neither aspect of swimming was affected by predator treatments.
Figure 6.
Tadpoles with shortened tails swam as fast as tadpoles with longer tails.
Agalychnis callidryas tadpoles that were reared with fish, either in the fish only predator treatment or the all predator treatment, had substantially shortened tails in comparison to tadpoles from other predator treatments. Tadpoles with shorter tails relative to their body size also exerted more tail beats per centimeter of distance swam.