Alternative scenarios for the timings of gene duplications in the KCNA family. (A) The timing of whole genome duplication relative to cyclostome-gnathostome split. Timings of genome duplications are shown as black arrows in the species phylogeny. (B) One possible gnathostome KCNA phylogeny. The 15 arrowheads above the branches of the gnathostome KCNA phylogeny indicate possible positions of individual sea lamprey genes in the tree topology. Black arrows indicate whole genome duplication. Two alternative tree topologies connecting 1) KCNA1/2 and KCNA5/10 and 2) KCNA3/6 and KCNA5/10 are not shown. Thus there are 45 possible tree topologies in total for a dataset containing the complete gnathostome gene set studied plus a sea lamprey gene. Arrowheads in black and white support scenarios I and II, respectively. Positioning of sea lamprey genes indicated with grey arrowheads cannot distinguish between scenario I and II. Numbers below each branch show the expected number of gene duplications for that branch before (left to the slash) and after (right to the slash) the cyclostome-gnathostome split.