Meeting Abstract
Animal life-history traits fall within limited ecological space, a continuum referred to as a “slow-fast” life-history axis. Differences in life-history traits are thought to result from trade-offs between investment in reproduction or self-maintenance as mediated by the biotic and abiotic environment. Dogs seem to be an anomaly to the typical correlations within these life-history trade-offs, with smaller dogs having higher mass-specific metabolic rates and longer lifespans compared with larger dogs. Thus, dogs provide a unique system to examine physiological consequences of life-history trade-offs. I have collected data from the literature to explore implications of these trade-offs at several levels of physiological organization including whole-animal, organ systems, and cells. Small dogs tend to have longer lifespans, fewer pups per litter, faster and shorter growth trajectories, higher mass-specific metabolic rates and, in general, larger metabolically active organs compared with large dogs. From work on isolated primary fibroblast cells and telomeres of dogs, I will show that selection for body size may influence attributes of cells that shape proliferative cellular rates and rates of telomere shortening. The potential links between body size, and cellular oxidative stress in dogs as they age will be discussed. Furthermore, small size in dogs has been linked to reduced insulin growth factor-1 (IGF-1) levels in plasma, a possible metabolic advantage that may provide higher resistance to oxidative stress, a parameter essential to increases in lifespan.
