DETERMINATION OF THE PHYLOGENETIC-RELATIONSHIPS AMONG PACIFIC SALMONIDS BY USING SHORT INTERSPERSED ELEMENTS (SINES) AS TEMPORAL LANDMARKS OF EVOLUTION

Several subfamilies of the salmonid Hpa I short interspersed element ( SINE) family were isolated from salmonid genomes and were sequenced. F or each genomic locus that represented the subfamily, amplification by PCR of the orthologous loci in the 12 fish allowed us to determine th e order of branching of the Pacific salmonid species. The deduced phyl ogeny suggests three evolutionary lines, namely, a line of chum salmon , pink salmon, and kokanee; a line of coho salmon and chinook salmon; and a line of steelhead trout. Our data also support a change in the p hylogenetic assignment of steelhead trout from Salmo to Oncorhynchus. We present here an extensive phylogenetic tree constructed from an ana lysis of differential insertion of SINEs, and we propose that SINE ins ertion analysis is one of the best available methods for clarifying th e order of divergence of closely related species.