Genetic variation and population structure of the Pacific cod Gadus macrocephalus in Korean waters revealed by mtDNA and msDNA markers

Abstract

To investigate the extent of genetic differentiation among wild populations of the Pacific cod Gadus macrocephalus, we have examined genetic polymorphism at five locations within Korean waters [Boryeong in the West Sea (WC-BR); Jinhae Bay in the South Sea (SC-JH); Jumunjin (EC-JM), Jukbyeon (EC-JB), and Bangeojin (EC-BJ) off the eastern coast of Korea] using mitochondrial DNA (mtDNA) control region and microsatellite DNA (msDNA) markers. Nucleotide sequence analysis of 584 bp in the variable portion of the 5 0 end of the mtDNA control region revealed 27 variable nucleotide sites among 184 individuals, which defined eight, three, and 11 haplotypes in the western, southern, and eastern coast populations, respectively. The mtDNA analysis revealed a low variability but significant local differentiation among populations from these three areas within Korean waters. msDNA analysis also revealed moderate polymorphism in the wild populations, with a mean of 13.8-22.6 alleles per locus for the five msDNA markers and observed (and expected) heterozygosities of 0.755 (0.825) for the WC-BR, 0.793 (0.810) for the SC-JH, 0.920 (0.905) for the EC-BJ, 0.783 (0.865) for the EC-JB, and 0.804 (0.812) for the EC-JM populations. Analysis of msDNA loci indicated that Pacific cod sampled at the WC-BR, SC-JH, and EC-JB sites belong to genetically distinct populations. However, no significant difference was found between the Pacific cod population from SC-JH and that from EC-BJ.Consequently, three genetically distinct populations, namely, WC-BR, SC-JH and EC-BJ, and EC-JB, were identified using msDNA analysis. These results indicate that genetically distinct populations of Pacific cod are present in Korean coastal waters where spawning aggregations occur.

Genetic variation and local differences in Pacific cod Gadus macrocephalus around Japan

“…In the present study, the use of the mtDNA nd2 showed appreciably more haplotype and nucleotide diversities than the use of the partial sequence of the mitochondrial control region, which has shown remarkably low diversity and shallow population structure in G. macrocephalus (Saitoh, ; Liu et al ., ; Gwak & Nakayama, ). Because the genetic differentiation among marine populations is expected to be low, highly polymorphic loci such as microsatellite markers are more powerful for identifying local population differentiation, as observed in several studies (Cunningham et al ., ; Gwak & Nakayama, ; Spies, ). Consequently, the mtDNA nd2 and multiple microsatellite markers were considered appropriate markers for revealing the presence of differentiation among G. macrocephalus samples collected from waters around Japan.…”

“…452 bp by Liu et al . () and 584 bp by Gwak & Nakayama (), detected very low diversity among the G. macrocephalus population across a wide range of regions. Canino et al .…”

“…Regional evaluations of G. macrocephalus populations have also been performed using similar methods, which identified small‐scale population structures (Cunningham et al ., ; Kim et al ., ; Stroganov et al ., ; Spies, ). Gwak & Nakayama () described three distinct populations in Korean waters that were sampled from the western, southern and eastern coasts of the Korean Peninsula using five microsatellite loci and an mtDNA control region. The genetic population structure of G. macrocephalus around Japan, however, has not been studied extensively, although Saitoh () detected no distinct genetic structure based on the mtDNA control region and random amplification of polymorphic DNA (RAPD) markers.…”

Comparison of Biological Characteristics of Pacific Cod Gadus microcephalus between the East and Yellow Seas, Korea

“…(Cha and Jung, 2012). (Seo et al, 2007;Lee et al, 2005;Cha et al, 2007), (Kim et al, 2013), (Choi and Gwak, 2011) , Park and Gwak (2009), , Yoon et al (2012), Baeck et al (2007, Seo et al (2010), Gwak and Nakayama (2011) , .…”

Ecological relationship between environmental factors and Pacific cod (Gadus macrocephalus) catch in the southern East/Japan Sea

“…In the southern East/Japan Sea, there are at least two spawning stocks (Zhang 1984;Gwak & Nakayama 2011): Jinhae Bay stock in Korean Peninsula and western Honshu (Noto Peninsula) stocks in Japanese islands ( Figure 1A). In Korean waters, cod spawn weakly adhesive demersal eggs Seo et al 2007), and spawning occurs mainly over sand and mud bottom during December through February with the peak in January (Lee et al 2009).…”