57.3 Thursday, Jan. 5 The relationship between insulin-like growth factor-1 and life history across Mammalia SWANSON, E.M.*; DANTZER, B.; Michigan State University; Michigan State University email@example.com
Life history traits describe parameters associated with growth, reproduction and survival. Life history variation is a hallmark of biological diversity, yet persistent patterns of variation are apparent among life history traits. A common observation is that as body mass increases species tend to have less rapid development, slow reproduction and long lifespan. This is often referred to as a 'fast-slow' life history axis. A similar fast-slow axis is still observed after correcting life history traits for body mass, though species tend to fall along this mass-corrected fast-slow axis at very different places than they do on the axis including mass. These persistent patterns of covariation have engendered a search for shared mechanisms than are important in the mediation of life history patterns. Neuroendocrine traits represent an important mechanism for the mediation of life history traits. Within species, insulin-like growth factor-1 (IGF-1) increases with increasing growth rate, increasing reproductive rate, and decreasing longevity. We used phylogenetic comparative methods to investigate the relationship between IGF-1 and multivariate axes of life history variation across the Class Mammalia. We find that increased IGF-1 is associated with fast life histories when mass is included. We also found that mass-corrected IGF-1 is associated with slow life histories after correcting life history traits for body size. Finally, we find that species with high levels of IGF-1 tend to have altricial young, with rapid prenatal development and extended postnatal development. We suggest that this association with fast-slow life history continua provides a plausible mechanism for a previously observed negative correlation between mass and IGF-1, and that the broad comparative relationship between IGF-1 and life history is similar to the intraspecific pattern.