Variation in age and size among breeding populations at different altitudes in the Japanese newts, Cynops pyrrhogaster

The age distribution of Cynops pyrrhogaster was studied by skeletochronology on 12 breeding populations inhabiting altitudes ranging from 120 m to 1140 m on Shikoku Island, Japan. In populations inhabiting altitudes 500 m or less, the mean SVL were smaller than in those that lived at higher altitudes. In populations inhabiting altitudes less than 500 m, minimum age at maturation was three years. In populations inhabiting altitudes of 500 m or more, the minimum age at maturation was four to seven years. The number of testes lobes was influenced by age and body size and was variable among populations.