Variations in take-off velocity of anuran amphibians: Relation to morphology, muscle contractile function and enzyme activity

The relationship between variability of take off velocity and variation in skeletomuscular features was examined in three anuran species, Rana nigromaculata, R. rugosa and Bombina orientalis. Video analyses on ''maximal'' take-off trials of individuals indicated that average take-off velocity (m . s(-1)) of R. nigromaculata (2.35 +/- 0.17 SD, n = 14) and R. rugosa (2.33 +/- 0.11 SD, n = 8) was significantly greater than that of Bombina (1.74 +/- 0.12, n = 8). Body mass (9.2 +/- 3.3 SD for R. nigromaculata; 11.5 +/- 5.6 SD for R, rugosa and 6.5 +/- 0.8 SD for B. orientalis) did not affect take-off velocity within each species. Compared to Bombina, the two ranid species showed longer hindlimbs relative to body length, greater mass of thigh muscles relative to body mass and a narrower interilial width (at the sacral vertebra) relative to body length. The two ranid species also exhibited significantly shorter tetanic rise time (TRT) and greater rate of force production (dF/dt) examined on the gastrocnemius muscle. Isometric tetanic force, ranging between 189 and 272 mN . mm was essentially the same among the three species. Activity of lactate dehydrogenase, an enzyme involved in anaerobic metabolism, of the gastrocnemius muscle, was statistically indistinguishable among the three species. The activity of citrate synthase (CS), indicative of aerobic catalytic capacity, was significantly lower in R. nigromaculata than in either R. rubosa or B. orientalis, while the CS activity was not different between the latter two species. These results indicate that the faster jumpers have a more effective skeletomuscular system (relatively longer hindlimbs and more musculature, higher contraction rate) that can generate a faster out velocity and a greater out-force against gravity. The enzyme assay study was not sufficient to support the observed relationships in these species.