[Source: Proceedings of the National Academy of Sciences of the United States of America, full page: (LINK). Abstract, edited.]
Reticulate evolution is favored in influenza niche switching
Eric J. Ma a,1, Nichola J. Hill a, Justin Zabilansky a, Kyle Yuan a, and Jonathan A. Runstadler a,b,1
Author Affiliations: aDepartment of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139; bDivision of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, MA 02139
Edited by Edward F. DeLong, University of Hawaii at Manoa, Honolulu, HI, and approved March 30, 2016 (received for review December 4, 2015)
Are the processes that result in the exchange of genes between microbes quantitatively advantageous for those microbes when switching between ecological niches? To address this question, we consider the influenza A virus as a model microbe, with its ability to infect multiple host species (ecological niches) and undergo reassortment (exchange genes) with one another. Here, through our analysis of sequence data from the Influenza Research Database and the Barcode of Life Database, we find that the greater the quantitative difference between influenza hosts, the greater the proportion of reassortment events were found. More broadly, for microbes, we infer that reticulate evolutionary processes should be quantitatively favored when switching between ecological niches.
Reticulate evolution is thought to accelerate the process of evolution beyond simple genetic drift and selection, helping to rapidly generate novel hybrids with combinations of adaptive traits. However, the long-standing dogma that reticulate evolutionary processes are likewise advantageous for switching ecological niches, as in microbial pathogen host switch events, has not been explicitly tested. We use data from the influenza genome sequencing project and a phylogenetic heuristic approach to show that reassortment, a reticulate evolutionary mechanism, predominates over mutational drift in transmission between different host species. Moreover, as host evolutionary distance increases, reassortment is increasingly favored. We conclude that the greater the quantitative difference between ecological niches, the greater the importance of reticulate evolutionary processes in overcoming niche barriers.
ecology – reticulate evolution – influenza – host switch – reassortment
1To whom correspondence may be addressed. Email: firstname.lastname@example.org or email@example.com.
Author contributions: E.J.M. designed research; E.J.M. performed research; E.J.M. and J.Z. contributed new reagents/analytic tools; E.J.M., N.J.H., J.Z., K.Y., and J.A.R. analyzed data; and E.J.M., N.J.H., and J.A.R. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
This article contains supporting information online at http://www.pnas.org/lookup/suppl/doi:10.1073/pnas.1522921113/-/DCSupplemental.
Keywords: Research; Abstracts; Influenza.