日本産アマガエルと欧州産アマガエルとの亜種間雑種

概要

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Crosses were made between female Japanese tree frogs, Hyla arborea japonica GUENTHER, and a male Hyla arborea sarda DE BETTA from the Corsica Island. A large number of normally creft eggs became normal swimming tadpoles, many of which completed their metamorphosis. As regards the rate of embryonic and larval development, the hybrids were slower than the control Hyla arborea japonica. At the stages shortly before, during and immediately after metamorphosis, the gonads of the hybrids were inferior in their development to those of the control japonica. The sex ratio was not 1:1; among 38 hybrids there were 8 males, 17 females and 13 hermaphrodites, having gonads transforming from ovaries to testes. Among eighteen nearly matured frogs, which were 10〜12 months old, there were no females with normal ovaries. Ten frogs had gonads transforming from ovaries to testes. Six others had testes of nearly normal structure, although spermatozoa were very few and abnormal in shape. The remaining two hybrids had distinctly degenerated testes. Such finding shows that the male and female hybrids are probably quite sterile. Accordingly, it is believed that Hyla arborea japonica and Hyla arborea sarda are genetically isolated from each other, in spite of their similarity in morphological characters.
1968-04-15