Phylogenetic tree showing the diversity of felid endogenous retroviruses. Maximum likelihood tree was based on deduced amino acid sequences of an RT fragment (Dataset1; 147 codons). Bootstrap values > 70% are indicated next to respective nodes (omitted for clarity on terminal branches). Host species’ designations are according to the inset graphical legend. G1 to G3 in red refer to distinct Gammaretrovirus groups identified based on the phylogenetic results and Gamma1-9 were previously described by Song et al. . Exogenous retroviruses and their respective genera are in green. Retroviral sequences retrieved from GenBank are listed in Additional file 1: Table S1. The scale bar at the bottom represents the evolutionary distance in amino acid substitutions per site.