For each of the two partitions, we tested alternative topological placement for the putative recombinant strain. Constraining the topology in ML analyses yielded likelihoods for alternative placements that were compared with the likelihood of the best ML tree using the approximately unbiased (AU) test [31] in CONSEL [32] . For this step, ML analyses were performed with PAUP* v.4.0b10 [33] and best trees were sought by heuristic searches (10 random addition replicates, TBR branch swapping, Multrees in effect).