دانلود رایگان مقاله تنوع ژنتیکی میتوکندری Rhinogobius giurinus

Abstract

Rhinogobius giurinus (Gobiidae: Gobionellinae) is an amphidromous goby that is widely distributed in East Asia. However, little is known about its population structure. In this study, R. giurinus from Japan, Taiwan and mainland China were used to evaluate the population genetic structure using mitochondrial DNA cytochrome b gene sequences (1122 bp). In total, 123 sequences were analyzed from seventeen populations. All 44 mtDNA haplotypes were identified as belonging to ten haplogroups, and four haplogroups were only distributed in the upstream of the Yangtze River and Hainan Island. The phylogeny and geography did not have a significant relationship. Our results (1) found that the mtDNA genetic diversity of this species was less than that of the freshwater goby; (2) showed that the lack of a population genetic structure might result in its amphidromous life cycle and high migrating potentiality; (3) indicated that although it is an amphidromous species, R. giurinus could not migrate across a deep sea, such as the South China Sea and Pacific Ocean; and (4) considered that the Kuroshio Current might act as a barrier for gene flows between East Japan and East China.

4. Discussion

A comparison of the NST (0.567) and GST (0.369) fixation indices showed that phylogeny and geography did not have a significant relationship. The mtDNA genealogy and network were not consistent with the groups defined based on their ichthyofauna (Figs. 1 and 3; Table 1). These results supported the finding that R. giurinus lacked a population structure. Compared with other goby, the mtDNA genetic diversity of R. giurinus (qp ¼ 0.679%) was smaller than that of R. maculafasciatus (qp ¼ 2.27%) (Cheng et al., 2005). However, R. maculafasciatus is an endemic freshwater fish in Taiwan. Previous studies (Allibone and Wallis, 1993; Doherty et al., 1995) proposed that freshwater species with a diadromous life cycle exhibited lower inter-population structures than did primary freshwater species. Accordingly, our study suggested that the lack of a population genetic structure for R. giurinus might result in its amphidromous life cycle.