Experimental warming reduces body mass but not reproductive investment

Climate change has already had wide-ranging effects on populations, including shifts in species' ranges, phenology, and body size. Whereas some common patterns have emerged, the direction and magnitude of responses vary extensively among populations as well as across life stages within populations. Understanding the consequences of climate change and predicting future responses at the population level require experimental tests of how warmer temperatures affect life history traits, including growth rate, development time, and reproductive output. Here, we tested how experimental warming affected life history from larval development and survival to adult reproductive maturity and investment in mole salamanders, Ambystoma talpoideum. We found that a small temperature increase (~1°C) experienced during larval development had complex consequences: density-dependent effects on growth and body mass, density-independent effects on fat storage, and no effects on survival and reproductive investment. Although warming reduced growth rates, size at maturity, and fat storage, salamanders in both warmed and control conditions had similar survival and reproductive investment in their first year. However, costs of smaller body size and lower fat reserves may limit overwintering survival and/or future reproduction. Our study highlights the differential effects of warming across life history traits and multifaceted population responses to climate change. This work motivates future studies to examine variation in response to climate change across life stages and life history traits.