Comparative study of two protein-coding regions of mitochondrial DNA from three endemic sculpins (Cottoidei) of Lake Baikal.

Two protein-coding regions (cytochrome b, ATPase 8, and part of ATPase 6) from mitochondrial DNA of Cottus kessleri, Cottocomephorus grewingki, and Cottocomephorus inermis--Baikalian endemic sculpins--were amplified via polymerase chain reaction, and sequenced. Two novel primers--L8352 (5'-TAAAGATTGGTGAC TCCCAACCACC) and H8773 (5'-GTAGGGAGT AAGCCCAATATGTT)--were used for the latter region. Phylogenies suggested by sequence divergence of the genes of ATPases appeared to be different from those computed from data for cytochrome b. The time of species branching was estimated as 1-2 million years (Myr) on the basis of merged sequences. Hence, members of the Baikalian cottoid species flock are much more distant from each other than members of the cichlid fish flocks of the great lakes of Africa (0.2 Myr). Topology of the phylogenetic tree does not contradict the relationships derived from morphological data. However, genetic distances suggest that C. grewingki and C. inermis are not sister species, contrary to general belief.