Subtle individual variation in indeterminate growth leads to major variation in survival and lifetime reproductive output in a long-lived reptile

1. The consequences of individual variation in life-history traits have been well studied due to their importance in evolutionary ecology. However, a trait that has received little empirical attention is the rate of indeterminate growth. In long-lived ectotherms, subtle variation in growth after maturity could have major effects over the animals’ lifetimes. 2. These effects are difficult to measure due to the challenges involved in reliably estimating individual variation in the face of environmental stochasticity, and the need to account for trade-offs among growth, reproduction and survival. However, modelling advances have made such analysis possible if long-term high-quality data sets are available. 3. We used an integrated state-space modelling framework to reveal relationships between indeterminate growth, reproduction and survival in a population of North American snapping turtles (Chelydra serpentina) using a 41-year data set for 298 adult females. 4. A hierarchical version of t...