Variation in age at metamorphosis across a latitudinal gradient for the tailed frog, Ascaphus truei

R. Bruce Bury; M. J. Adams

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USGS · 1015987

Variation in age at metamorphosis across a latitudinal gradient for the tailed frog, Ascaphus truei

R. Bruce Bury·M. J. Adams

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Abstract

Tailed frogs ( Ascaphus truei ) occur in permanent, cold streams in northwestern North America. Their tadpoles reportedly undergo metamorphosis after 2-4 years. Coastal populations that we examined transformed in 2 yr from the Olympic peninsula in Washington to northern Oregon, but in 1 yr from central Oregon to northern California. One inland site in northern California had a 2-yr period. Age at metamorphosis was consistent over different years. We suggest that total length and developmental stage accurately define cohorts for larval Ascaphus . Hind-leg length indicates whether metamorphs are a separate age class from tadpoles. Age at metamorphosis (1-4 yr) appears to reflect broad differences in climatic conditions. However, at a regional scale, variation is low and suggests a lack of sensitivity to local environmental conditions. This may be due to seasonal constraints on the time when metamorphosis occurs (late summer).

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R. Bruce Bury, M. J. Adams. 1999. Variation in age at metamorphosis across a latitudinal gradient for the tailed frog, Ascaphus truei. https://pubs.usgs.gov/publication/1015987

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