Study On The Morphological Characters And Genetics Of Lophius Litulon

Lophius litulon of Yellow Sea and Japan Sea were analyzed by using morphology and isozyme methods, furthermore, phylogenetic relationships among L. litulon, M. tiarella, H. gronlandicus, Chaunax sp.1 and Chaunax sp.2 were studied by using Mitochondrial DNA sequencing techniques in order to supply some base data for domestic study and exploit rationally L. litulon and sustainably utilize it. Results of the research fill up the blank in the field of Lophiiformes fishes genetics. It is important to protect the genetics diversity of L. litulon. The main results of this paper were listed below:The biological characteristics of L. litulon of Yellow Sea and Japan Sea were analyzed through conventional measurement and statistic analysis in this paper. Morphological characters of L. litulon were described in detail. The results showed that the mean number of the second dorsal fin rays between two populations was difference while, the mean number of Pectoral fin rays, Pelvic fin rays, Anal fin rays, Caudal fin rays and Vertebrae were no difference. Measurable characters of two populations: BL/HL,BL/BW,BL/CPL,HL/SL,EI/ED,CPL/CPW were difference and BL/ABL,HL/ED were no difference.Horizontal starch gel electrophoresis was employed to investigate the genetic structure and genetic diversity of these two populations. Eight isozymes systems in L. litulon of Yellow Sea are encoded by 8 loci, and 4 of them were polymorphic, i.e., LDH*,AAT*,GPI* and G3PDH*. The proportion of polymorphic loci is 0.5(P0.99). The meanvalues of observed and expected heterozygosities (Ho& He) are 0.027 and 0.026 respectively and the average effective number of alleles is 1.028. Genetic deviation index shows heterozygotes surplus at these loci. Six isozymes systems in L. litulon of Japan Sea are encoded by 6 loci, and none of them were polymorphic. The Nei's genetic distance between two populations was 0.00046, which suggested that genetic diversity in this species be relatively low without significant genetic divergence between the geographic populations.The mitochondrial DNA COI gene fragments of L. litulon, M. tiarella, H. gronlandicus, Chaunax sp.1 and Chaunax sp.2 were amplified and sequenced. Results of the mitochondrial COI gene sequence revealed that deletion/insertion were detected among COI gene fragments. Nucleotide composition analysis revealed that the five species showed a strong bias against guanine (G) in the three protein-coding genes, especially in Chaunax sp.1 (17.6%). The A+T content was higher than that of C+G.. One hundred and sixty-nine variation sites were detected among the five species. The largest genetic distance was found between L. litulon and Chaunax sp.2 and genetic distance between Chaunax sp.1 and Chaunax sp.2 was smallest. In addtion, phylogenetic relationships revealed by the phylogenetic tree constructed based on COI gene fragments of five species are consistent with present morphological systematics of these species, which showed that mtDNA COI can be one of genetic markers available for phylogenetic development of Lophiiformes fishes.