The average water temperature and pH in tanks was 19.29 ± 0.10 °C (SE, range: 17.0–22.5) and 8.59 ± 0.01 (SE, range 8.2–8.9) respectively. There was no significant difference among treatments (water temperature: F = 0.0086, df = 5, p = 1.0000, pH: F = 0.0063, df = 5, p = 1.0000).
Intraspecific competition (density = 5, 15, 50 tadpoles per tank)
The density of conspecifics did not have any significant effect on survival to metamorphosis of B. j. formosus (treatment: Wald chi-square = 3.468, df = 2, p = 0.1766; block: Wald chi-square = 7.770, df = 4, p = 0.1004; Fig. 1a). However, conspecific density had a significant effect on the combined responses of variables (larval period, metamorph SUL, metamorph mass) of B. j. formosus (MANOVA treatment: Wilks’ Lambda = 0.0181, F = 10.7224, df = 6, 10, p = 0.0007; block: Wilks’ Lambda = 0.2028, F = 0.9326, df = 12, 13.52, p = 0.5441). Higher densities of conspecifics increased the duration of the larval period (treatment: F = 6.678, df = 2, 9.30, p = 0.0159; block: F = 0.817, df = 4, 0.40, p = 0.7574; Fig. 1b), and decreased size at metamorphosis (SUL—treatment: F = 49.729, df = 2, 6.94, p < 0.0001; block: F = 1.154, df = 4, 6.88, p = 0.4074; Fig. 1c; mass—treatment: F = 22.949, df = 2, 6.66, p = 0.0010; block: F = 1.031, df = 4, 6.68, p = 0.4566; Fig. 1 d).
The effect of tadpole density on survival, larval period and metamorph size of toads, Bufo japonicus formosus. The treatments comprised densities of 5, 15 or 50 tadpoles per container. The panels show impacts on (a) survival rate, (b) larval period, (c) metamorph snout-urostyle length, and (d) metamorph mass. The graphs show mean values (based on 5 replicate containers per treatment) with standard errors. The same letter indicates that the differences are not significant using a post hoc test (Tukey’s HSD) at the 0.05 level.
Interspecific competition (density = 50 tadpoles per tank)
There was no significant effect of treatment (competitor species) on survival of B. j. formosus to metamorphosis (treatment: Wald chi-square = 4.076, df = 3, p = 0.2533; block: Wald chi-square = 2.708, df = 4, p = 0.6078; Fig. 2a). MANOVA also showed no significant effect of treatment on overall responses (i.e., including variables of larval period, metamorph SUL, metamorph mass) of B. j. formosus (treatment: Wilks’ Lambda = 0.3722, F = 1.2275, df = 9, 22.05, p = 0.3285; block: Wilks’ Lambda = 0.3269, F = 1.0565, df = 12, 24.10, p = 0.4344). Although tadpoles of B. j. japonicus tended to impose stronger negative effects on B. j. formosus than did B. j. formosus on itself (Fig. 2b–d), there was also no significant effect of competitor species on the duration of the larval period for B. j. formosus (treatment: F = 2.262, df = 3, 9.83, p = 0.1448; block F = 0.783, df = 4, 9.56, p = 0.5627, Fig. 2b), or size at metamorphosis (SUL—treatment: F = 1.895, df = 3, 10.46, p = 0.1917; block: F = 2.039, df = 4, 10.46, p = 0.1615; Fig. 2c; mass—treatment: F = 2.706, df = 3, 10.69, p = 0.0980; block: F = 0.495, df = 4, 10.68, p = 0.7403; Fig. 2d).
The effect of interspecific competition on survival, larval period and metamorph size of toads, Bufo japonicus formosus. The treatments comprised 50 B. j. formosus tadpoles, or 25 tadpoles of B. j. formosus plus 25 tadpoles of B. j. japonicus, Rana japonica or R. ornativentris. The panels show impacts on (a) survival rate, (b) larval period, (c) metamorph snout-urostyle length, and (d) metamorph mass. The graphs show mean values (based on 5 replicate containers per treatment) with standard errors.
Source: Ecology - nature.com
