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R. J r and Laurin. G. 1996. Growth and body size in populations of mink frogs Runu seprenfrionulis from two latitudes. -Ecognphy 1 9 296-304.Age. longevity, and growth in mink frogs Runa srprenfriunulis from two latitudes in Quebec, Canada, were assessed by skeletochronological and backcalculation methods in order to document proximate causes for intraspecific variations in adult body size. In both study sites, females grew faster and were on avenge 11% larger than males. Mean age and maximal longevity were significantly higher in females than in males only in the southern populations. There was thus an interpopulation diference in the relative contribution of age and growth to sexual size dimorphisms. Sex-ratio also Favored females (males suffering higher mortality) only in the southern populations. Specimens from the northern population had higher mean ages (but not higher longevities) and were 17% larger than specimens from the southern populations. Annual growth rate appeared similar at the two study sites despite a shorter growing season at the northern locality. Maturity was reached by both sexes after 1 yr of post-metamorphic life (PML) in the southern populations but after 2 yr of PML in the northern population. There are indications that tadpoles metamorphose at larger body size at the northern locality after a prolonged larval period. It is concluded that growth rate, delayed maturity, greater mean ages. and eventually size at transformation, all contribute to the larger size of adult mink frogs at northern localities.

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