Title

Evolution in spatially mixed host environments increases divergence for evolved fitness and intrapopulation genetic diversity in RNA viruses

DOI

https://doi.org/10.1093/ve/vev022

Document Type

Article

Publication Date

1-1-2016

Publication Title

Virus Evolution

Abstract

Virus populationsmay be challenged to evolve in spatially heterogeneous environments, such asmixtures of host cells that pose differing selection pressures. Spatial heterogeneitymay select for evolved polymorphisms, wheremultiple virus subpopulations coexist by specializing on a narrow subset of the available hosts. Alternatively, spatial heterogeneitymay select for evolved generalism, where a single genotype dominates the virus population by occupying a relatively broader host niche. In addition, the extent of spatial heterogeneity should influence the degree of divergence among virus populations encountering identical environmental challenges. Spatial heterogeneity creates environmental complexity that should increase the probability of differing adaptive phenotypic solutions, thus producing greater divergence among replicate virus populations, relative to counterparts evolving in strictly homogeneous host environments. Here, we tested these ideas using experimental evolution of RNA virus populations grown in laboratory tissue culture. We allowed vesicular stomatitis virus (VSV) lineages to evolve in replicated environments containing BHK-21 (baby hamster kidney) cells, HeLa (human epithelial) cells, or spatially heterogeneous host cellmixtures. Results showed that generalist phenotypes dominated in evolved virus populations across all treatments. Also, we observed greater variance in host-use performance (fitness) among VSV lineages evolved under spatial heterogeneity, relative to lineages evolved in homogeneous environments. Despitemeasurable differences in fitness, consensus Sanger sequencing revealed no fixed genetic differences separating the evolved lineages from their common ancestor. In contrast, deep sequencing of evolved VSV populations confirmed that the degree of divergence among replicate lineages was correlated with a larger number of minority variants. This correlation between divergence and the number ofminority variants was significant only when we considered variants with a frequency of at least 10 per cent in the population. The number of lower-frequencyminority variants per population did not significantly correlate with divergence.

Volume

2

Issue

1

Identifier

SCOPUS_ID:85016783246

Documento original

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