Ratio Between Growth and Tail Reduction in the Tadpoles of Phyllomedusa nordestina (Anura, Hylidae)

Abstract

Tadpoles have intra- and interspecific morphological plasticity that correlate them to their development habitat and environment occupation. Studies relating plasticity and development of tadpoles can agglutinate information for understanding basal and derivatives aspects of semaforontes. We evaluated the morphological development of tadpoles Phyllomedusa nordestina in transition between stages 45 and 46 of aiming at establishing a probable ratio between growth and metamorphosis. The biometry was composed of the segments body length, tail length, total length, and body mass. Individuals were measured every three hours and filmed twenty-four hours a day, with a camcorder of  resolution Pal628x582; NTSC510x492, three lux lighting, 3.6 mm lens. The variables were subjected to multivariate allometry being the correlation between variables established by Pearson's correlation coefficient. The tail reduction shows positive allometry. The tail length reduces within 36 hours while the body length remains constant. It means that the tail presents an isogonic condition in relation to the body length. The relationship between body mass and tail reduction has a negative dependence (r = - 0.87) with a nonlinear power regression (y = 0.0573x– 6.16. We conclude that the tadpoles’ body at the end of the tail reduction presents its total length constant, however the body mass increases, which means that the body increases in volume without increasing its total length. This pattern is supposed to be related to the ecotonal dry environmental conditions of the municipality of Floriano, State of Piauí.