Larval growth rate and metamorphic timing are often decoupled in biphasic, stream-breeding plethodontid salamanders; however, both of these life-history traits are plastic and variation among populations is driven partially by environmental factors such as water temperature. Urbanization often alters these environmental factors, possibly impacting the life history of the plethodontid populations remaining in these highly disturbed stream systems. We investigated the larval life history of Eurycea cirrigera (Southern Two-Lined Salamander) across an urban gradient in Atlanta, GA, USA, to disentangle the effects of urbanization, temperature, and stream size on larval period length and larval size. Across 14 urban streams, E. cirrigera larval period length was negatively correlated with summer stream temperatures; only streams with warmer summer stream temperatures lacked a 2-yr larval period. In addition, summer stream temperatures were positively correlated with larval size. Higher impervious surface cover (ISC) of the drainage basin was correlated with larger larval size, but mostly through the positive effect of ISC on stream temperature. These results expand our understanding of the mechanisms underlying variation in plethodontid life history and underscore the potential impacts of urbanization on amphibian populations.

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