Ovarian Functional Patterns in Baltic and Mediterranean Populations of a Temperate Zone Anuran, the Toad Bufo viridis

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Abstract
The relationship between body mass and mass of the ovaries at completed vitellogenesis in Danish and Israeli populations of B. viridis could be described by the allometric equation, ovarian mass = 0.084 (body mass)1.23. The number and size of full grown oocytes varied both between and among populations, the intra-populational variation being greatest among the toads from Jerusalem. Number and size of oocytes varied inversely, so that final volume, and thus mass, of the egg complements established a constant relation to body mass. The ovaries of adult female B. viridis are potentially capable of recruiting oocytes to vitellogenic growth at any time of the yr. Vitellogenic ovarian cycles may therefore depend upon external factors. At the northern limits of distribution the basic environmental factor is presumably the annual cycle in temperature. At the southern limit the annual pattern of precipitation may control breeding, and thus act as a synchronizer of ovarian function within the population. The plasticity of ovarian function presumably originates from features of the reproductive system that are common to lower vertebrates producing large complements of relatively small eggs.