Mortality and lifespan

摘要

How does natural selection affect lifespan? The question has exercised biologists for some years. The latest twist comes from ingenious experiments on tropical fish from different ecological backgrounds. On page 1095 of this issue, Reznick et al. describe how they have investigated one of the main factors that influence the evolution of an organism's lifespan. That factor is the risk of dying that a population faces as a result of environmental conditions (such as, in this case, predation). The studysubjects are guppies, small tropical fish that are widely used in evolutionary studies, and the authors provide the first experimental support for the prediction that a higher environmental risk of mortality can select for inherently longer-lived organisms.