Taxonomy Advancement and Genome Size Change: Two Perspectives on RNA Virus Genetic Diversity
Chris Lauber and Alexander E. Gorbalenya
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: 215-232.
Relatively frequent insertion and deletion events, ranging from single nucleotides to full-length genes, and extreme point mutation rates make macroevolutionary studies of RNA viruses an exquisite challenge. Here we review recent advancements in the field concerning the study of both of these aspects and with regard to two specific applications - virus taxonomy and the analysis of genome size evolution. For the former we observe a dominant trend towards utilizing results from genetics-based virus classification during recent years. We also briefly discuss parallel developments for taxonomic studies of cellular organisms where very similar techniques are applied, but observe little cross-talk with virus taxonomy. For RNA virus genome size evolution we outline an emerging general pattern of genome (segment) enlargement being associated with a host- and mutation-constrained step-wise acquisition of key enzymes that seemingly improved the rudimentary RNA virus replication machinery. We discuss possible consequences for the upper limit on the size of the RNA virus genome segment currently observed for single-segment positive stranded nidoviruses read more ...