Fig. 3

Phylogenetic network based on the alignment of corresponding COI sequence fragments from the four studied species Eulimnogammarus verrucosus, E. vittatus, E. cyaneus and Gammarus lacustris. Respective COI sequences from E. maackii (AY926663.1), E. viridulus (AY926665.1), E. viridis (AY926664.1) [16] and Brachyuropus grewingkii (NC_026309.1) [6] serve as outgroups. The scale bar indicates the number of substitutions per base pair. The asterisk designates a sample of G. lacustris (GU066811.1) from Yellowstone Lake, USA [61]. See Additional file 5: Fig. S2 for the maximum likelihood tree of these sequences