When replicating its (+)ssRNA genome, the poliovirus  RdRp is able to carry out recombination.  Recombination appears to occur by a copy choice mechanism in which the  RdRp switches (+)ssRNA templates during negative strand synthesis.  Recombination frequency is determined in part by the fidelity of  RdRp replication.   RdRp variants with high replication fidelity show reduced recombination, and low fidelity  RdRps exhibit increased recombination.   Recombination by  RdRp strand switching also occurs frequently during replication in the (+)ssRNA plant carmoviruses and tombusviruses.