Phylogenetic tree of 164 BTV-8 samples collected during the European outbreak between 2006 and 2018 with tip labels.

ML tree estimated in PhyML. The scale shows substitutions per site. Clades represented 700 or more times within 1,000 bootstraps are indicated by a white circle. Samples from the first outbreak are shown with purple circles, while samples form the second outbreak are shown with an orange circle. BTV-8, bluetongue virus serotype 8; ML, maximum likelihood.