Understanding Adaptation Through Experimental Evolution with Viruses: From Simple to Complex Environments
Valerie J. Morley and Paul E. Turner
from: Virus Evolution: Current Research and Future Directions (Edited by: Scott C. Weaver, Mark Denison, Marilyn Roossinck and Marco Vignuzzi). Caister Academic Press, U.K. (2016) Pages: 233-262.
A central goal of evolutionary biology is to better understand the processes that promote versus constrain adaptation in evolving populations; this aim is crucial for refining predictions on whether or not populations will successfully adapt to environmental change. Experimental evolution of viruses in controlled laboratory settings provides a powerful method for investigating generalized theories of adaptive evolution, and a vital approach for testing particular predictions on virus adaptive potential. Examples include the use of viruses to elucidate the dynamics of clonal interference between beneficial mutations vying to undergo fixation, the prevalence and character of epistatic interactions between genes, and the relative potencies of natural selection versus genetic drift in dictating evolutionary outcomes. While these efforts have helped refine predictions on adaptation occurring in constant environments, adaptation in complex or heterogeneous environments remains relatively seldom studied. Although organisms commonly encounter environments that are spatially and/or temporally complex, investigating the effects of environmental heterogeneity on evolution proves challenging in most study systems. Recent studies demonstrate that experimental evolution in viruses is a tractable and rigorous approach for resolving how evolution proceeds in heterogeneous environments. In this chapter, we review virus experiments that illuminate how basic evolutionary forces - especially selection, drift and migration - operate to dictate the fate of alleles and populations in simple and complex environments. We also suggest many exciting and open questions that remain to be explored using virus experimental models, such as empirical mapping of fitness landscapes, and the role of heterogeneous environments in promoting versus constraining virus adaptation read more ...