Fig. 4.

Phylogenetic evidence that MSV-A variants move between and become established in different regions of Africa more frequently than MSV-B variants. (a) Relationships amongst MSV-B sequences from wild and cultivated grass species in East Africa (red circles), southern Africa (blue circles) and La Réunion (yellow circles). (b) The relationships amongst MSV-A isolates from wild grasses and maize sampled in West Africa (green circles), East Africa (red circles), southern Africa (blue circles) and La Réunion (yellow circles). Both trees were constructed using sequence alignments from which tracts of recombinationally derived sequences were deleted (i.e. they are largely recombination free). Also in both trees, branches with less than 50 % bootstrap support have been collapsed and branches with 70 (○) or 90 % (•) bootstrap support are labelled. Bar, 0.005 nucleotide substitutions per site.