ИСТИНА

In a series of experiments it was shown that there is a correlation between the morphometric characteristics of the tadpoles and the conditions of their embryonic development. The growth parameters, such as ventral body length and dorsal body length, of Bufo tadpoles depend on the conditions of embryonic development (Dmitrieva, 2005, 2012). Tadpoles that came from the eggs that developed in low density were significantly larger than those in the high density group. Tadpoles hatched from the eggs that developed in a stretched egg cord had much greater dorsal body length than those hatched from the lose egg cord. In another series of experiments, eggs of the common toad had been placed in different oxygen concentration: oxygen deficiency and normal oxygen supply. After hatching tadpoles were split into groups 2 and 5 individuals per 0,3L. The experiments were finished after the formation of metatarsal tubercle (st.36, Gosner, 1960). The oxygen deficiency during embryogenesis influenced primarily formation of tadpole head characteristics: distance between the margins of the nostrils (Sp.n.), ratio Sp.n. to distance between centers of eyes (Sp.c.r), and ratio Sp.n. to body width (Wd.b). Tadpoles, which developed in conditions of oxygen deficiency, were significantly larger than those developed in normal oxygen supply in Sр.n./Wd.b and Sр.n./Sp.c.r. The influence of oxygen deficiency on the formation of Sp.n. varied between clutches: under high density of tadpoles in two clutches Sp.n. was larger in individuals that developed under conditions of normal oxygen concentration, and in the other clutches – in the oxygen deficiency conditions.