In the Rana temporaria population introduced into the south of Kamchatka, high variation in the rate of larval growth and development was revealed, due to differences between spawning pools, some of which being fed by thermal groundwater. As a consequence, the variability in the timing of metamorphosis was also high and comparable to that detected in populations of the native part of the range with a longer period of activity. In the tadpoles of R. temporaria from this Kamchatka population, an essential developmental delay was revealed for the first time in the early stages (37–42 days from the 39^th to 40^th stage according to Dabagyan and Sleptsova, 1975). The cause of this delay may be a strong limitation of the development rate by low water temperature and high density of individuals. The confirmed case of the formation of a new local population of the species as a result of dispersal from the studied population indicates the effectiveness of selection on faster growth and development of tadpoles and the possibility of forming new populations outside the areas of thermal water outlets.