MI67CH25-Turner ARI 19 June 2013 8:14 V I E E W R S Review in Advance first posted online on June 28, 2013. (Changes may still occur before final publication E online and in print.) I N C N A D V A On the Biological Success of Viruses Brian R. Wasik and Paul E. Turner Department of Ecology and Evolutionary Biology, Yale University, New Haven, Connecticut 06520-8106; email:
[email protected],
[email protected] Annu. Rev. Microbiol. 2013. 67:519–41 Keywords The Annual Review of Microbiology is online at adaptation, biodiversity, environmental change, evolvability, extinction, micro.annualreviews.org robustness This article’s doi: 10.1146/annurev-micro-090110-102833 Abstract Copyright c 2013 by Annual Reviews. Are viruses more biologically successful than cellular life? Here we exam- All rights reserved ine many ways of gauging biological success, including numerical abun- dance, environmental tolerance, type biodiversity, reproductive potential, and widespread impact on other organisms. We especially focus on suc- cessful ability to evolutionarily adapt in the face of environmental change. Viruses are often challenged by dynamic environments, such as host immune function and evolved resistance as well as abiotic fluctuations in temperature, moisture, and other stressors that reduce virion stability. Despite these chal- lenges, our experimental evolution studies show that viruses can often readily adapt, and novel virus emergence in humans and other hosts is increasingly problematic. We additionally consider whether viruses are advantaged in evolvability—the capacity to evolve—and in avoidance of extinction. On the basis of these different ways of gauging biological success, we conclude that viruses are the most successful inhabitants of the biosphere.