Fig. 2

Neighbour-joining (NJ) phylogenetic tree calculated from the ankA gene sequences. Tree construction was achieved by the NJ method using the Jukes-Cantor matrix with the complete deletion option. Bootstrap values are shown next to the branches. The scale-bar indicates the number of nucleotide substitutions per site. The final data set contained 520 positions. GenBank accession numbers are given after the sample designation. Animals infected with only one ankA allele are symbolized by black circles. Those harboring more than one ankA allele over time are represented by green, red, yellow, purple, light blue, pink and dark blue circles. Ambiguous nucleotides in heifers with different ankA allele at the same collection date were resolved before tree construction. Animals infected simultaneously with two different ankA alleles are represented by diamonds at the respective time point