Neighbor-joining tree for all single-domain Kunitz/BPTI proteins in ticks. The circular phylogram (NJ tree) is based on alignment of all single-domain Kunitz/BPTI proteins in Ixodes scapularis and other ticks. The red branches have bootstrap support above 50%. Group II and group III, which are highlighted, are lineage-specific expansions of Kunitz/BPTI family in the genus Ixodes. The support values for these two groups (in MB, NJ, and ML tree) were shown in left bottom. The circle, square and triangle in the phylogram indicate the proteins from soft ticks, the genus Ixodes (hard ticks) and other hard ticks, respectively. The sequence name consists of 5 letters (3 from the genus and 2 from the species name) with the NCBI accession number. (Argmo, Argas monolakensis; Ornco, Ornithodoros coriaceus; Ornmo, Ornithodoros moubata; Ornpa, Ornithodoros parkeri; Ornsa, Ornithodoros savignyi; Rhiap, Rhipicephalus appendiculatus; Rhisa, Rhipicephalus sanguineus; Ixosc, Ixodes scapularis; Ixopa, Ixodes pacificus; Ixori, Ixodes ricinus; Rhimi, Rhipicephalus microplus; Hyama, Hyalomma marginatum rufipes; Ambam, Amblyomma americanum; Haelo, Haemaphysalis longicornis).