Mid-life temperature-transfer effects on life-span of annual fish

When annual fish are transferred from 20 C. to 15 C. at slightly less than the midpoint of lifespan of those kept throughout life at 20 C., the survival of the transferees exceeds theoretical expectations. They live longer than those maintained throughout life at 15 C., which had previously manifested the longest survival. These results indicate that the influence of temperature on life-span is not uniform throughout the life of a poikilothermic vertebrate. The phenomenon of partial temperature-independency had been previously demonstrated in invertebrates.