Figure 4. Proposed origin of osteichthyans Kissr loci based on human and spotted gar Kissr tetra-paralogons.

The paralogous genes of each of the eight identified families delineate four tetra-paralogons in both human and spotted gar. This suggests a common origin of the four loci before the two whole genome duplication rounds (1R and 2R) occurred in the early vertebrate history.