RNA viruses typically have a high mutation rate due to low fidelity and processivity of their polymerase [25] , which coupled with a high replication rate and short generation time [26] lead to high evolutionary rates. In addition, evidence is accumulating that recombination is an important process driving genotype diversity for many RNA viruses [27, 28, 29] . Although recombination was not thought to contribute to aPMV-1 evolution [30, 31] , evidence of recombination in NDV has recently been reported [32, 33, 34] . This debate may be due, in part, to the reliance on a single gene for determining virus diversity and phylogeny. Because recombination can lead to the emergence of novel virus strains of unknown virulence [35, 36, 37, 38] , a better understanding of the role of recombination in circulating aPMV-1 is warranted.