More on Predation Versus Longevity
Biology is diversity; while the rule on predation and the evolution of longevity seems to hold for most species, there are always outliers: "mice are low on the food chain and rather likely to meet a bad end; consequently, there’s very little opportunity for genes that enhance longevity to benefit the animal (or even get expressed in the first place). Based on examples of this kind, biologists of aging generally predict that lower extrinsic mortality from predation is a positive influence on the evolution of longevity. Hence, it is surprising that guppies exposed to predation actually appear to live longer (and age more slowly) than similar fish from a similar environment without predators. ... This is an exception to two classical predictions of evolutionary theory: that low extrinsic mortality should be associated with longer life span, and that higher fertility should be associated with shorter life span. Some theorists have tried to accommodate this and other anomalous results within the standard framework, but we argue that the exceptions they carve out do not explain the results at hand. In fact, the findings suggest that population regulation has been selected at the group level, though this is a mechanism that most theorists regard with suspicion."
Link: http://ouroboros.wordpress.com/2008/01/11/predation-vs-longevity-a-counterexample/