Figure 6

Model of ancestral linkage group re-arrangements among G/H/I lineage chromosomes. Extensive cross syntenies among zebrafish chromosomes 5, 10, 15, and 21 suggest that a duplication and subsequent fission of one of the two 3R chromosomes in either the I, or presumptive G/H lineage may have occurred. This fission would give the appearance of extra ancestral groupings (i.e., greater than 4 linkage group arm homologies to either the G/H or the I lineage chromosomes). Reticulate exchange among segments from both ancestral groupings may also have occurred as evidenced by the retention of G/H/I synteny blocks within rainbow trout arms 1 and 9p. Rainbow trout chromosome arms possessing multiple affinities to zebrafish linkage groups 5/10/15/21 (i.e, suggestive of greater re-arrangements), are indicated in red font in the centre of the table.