Open AccessInvasion thresholds and the evolution of nonequilibrium virulence
Author(s) -
Bull James J.,
Ebert Dieter
Publication year - 2008
Publication title -
evolutionary applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.776
H-Index - 68
ISSN - 1752-4571
DOI - 10.1111/j.1752-4571.2007.00003.x
Subject(s) - virulence , biology , host (biology) , parasite hosting , population , genetic fitness , experimental evolution , evolutionary biology , transmission (telecommunications) , selection (genetic algorithm) , genetics , biological evolution , gene , demography , artificial intelligence , sociology , world wide web , computer science , electrical engineering , engineering
The enterprise of virulence management attempts to predict how social practices and other factors affect the evolution of parasite virulence. These predictions are often based on parasite optima or evolutionary equilibria derived from models of host‐parasite dynamics. Yet even when such models accurately capture the parasite optima, newly invading parasites will typically not be at their optima. Here we show that parasite invasion of a host population can occur despite highly nonoptimal virulence. Fitness improvements soon after invasion may proceed through many steps with wide changes in virulence, because fitness depends on transmission as well as virulence, and transmission improvements can overwhelm nonoptimal virulence. This process is highly sensitive to mutation supply and the strength of selection. Importantly, the same invasion principle applies to the evolution of established parasites, whenever mutants arise that overcome host immunity/resistance. A host population may consequently experience repeated invasions of new parasite variants and possible large shifts in virulence as it evolves in an arms race with the parasite. An experimental study of phage lysis time and examples of mammalian viruses matching some of these characteristics are reviewed.