The Evolution of Viruses in Multi-Host Fitness Landscapes

Santiago F Elena*, Patricia Agudelo-Romero, Jasna Lalić
Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-UPV, 46022 València, Spain

© Elena et al.; Licensee Bentham Open

open-access license: This is an open access article licensed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted, non-commercial use, distribution and reproduction in any medium, provided the work is properly cited.

* Address correspondence to this author at the Instituto de Biología Molecular y Celular de Plantas, Campus UPV CPI 8E, Ingeniero Fausto Elio s/n, 46022 València, Spain; Tel: +34 963 877 895; Fax: +34 963 877 859; E-mail:


Provided that generalist viruses will have access to potentially unlimited hosts, the question is why most viruses specialize in few hosts. It has been suggested that selection should favor specialists because there are tradeoffs limiting the fitness of generalists in any of the alternative hosts or because evolution proceeds faster with narrower niches. Here we review experiments showing that virus adaptation to a specific host is often coupled with fitness losses in alternative ones. In most instances, mutations beneficial in one host are detrimental in another. This antagonistic pleiotropy should limit the range of adaptation and promote the evolution of specialization. However, when hosts fluctuate in time or space, selective pressures are different and generalist viruses may evolve as well.