The characteristics and phylogenetic relationship of two complete mitochondrial genomes of Cottus pollux (scorpaeniformes: cottidae).

We report two complete mitochondrial genomes of Cottus pollux based on specimens collected from Deokdong and Hoam Streams in the Republic of Korea. The two complete mitochondrial genomes were 16,558 and 16,557 bp long. Both contain the 37 standard genes (13 protein-coding genes, 22 transfer RNA genes, two ribosomal RNA genes, and one control region) in the same order and have similar nucleotide compositions. According to the phylogenetic tree constructed using the maximum-likelihood method, C. pollux is closely related to C. reinii. The genetic information provided by the complete mitochondrial genome of C. pollux will contribute to an understanding of the phylogenetic position, evolutionary relationships, and biogeographical patterns of this species within the genus Cottus.

The Impact of Weir Construction in Korea's Nakdong River on the Population Genetic Variability of the Endangered Fish Species, Rapid Small Gudgeon (Microphysogobio rapidus).

Microphysogobio rapidus, an endemic cyprinid fish species found exclusively in Korea, has been identified in only two tributaries of the Nakdong River. The species predominantly occupies the near-gravel bottom waters within shallow sections of the middle and lower reaches of the river, characterized by swift currents. M. rapidus is currently recognized as a critically endangered species due to its distinct habitat preference, as well as the negative impacts of stream dam development and water environment pollution. In this study, we used 10 microsatellite markers to examine the genetic diversity of M. rapidus in the upper Nam (UN), lower Nam (LN), and Deokcheon Rivers (DC) in Korea, with a specific focus on assessment of the impact of dam development. Fish sampled from the UN and LN showed a greater average number of alleles and allelic richness (A = 18.3-18.4, AR = 13.8) compared to those from DC (A = 11.8, AR = 11.5). The observed heterozygosity among the fish examined ranged from HO = 0.748 (LN) to 0.766 (DC). All three fish groups exhibited a significant departure from Hardy-Weinberg equilibrium (HWE) (p < 0.05). Despite having the largest effective population size (Ne = 175 and 157, respectively), the fish sampled from UN and LN showed the highest inbreeding coefficients (FIS = 0.056-0.053, respectively), which were highly significant (p < 0.01). In contrast, the fish sampled from DC exhibited the smallest effective population size (Ne = 61) and showed an inbreeding coefficient close to zero (p > 0.05). BOTTLENECK analysis and estimated M-ratio values (0.341-0.372) revealed indications of past population size reduction in all fish groups examined. No significant genetic differentiation (FST < 0.05) was detected using the DAPC, STRUCTURE, and AMOVA among the fish studied. However, pairwise comparisons of FST between fish sampled from the Nam and Deokcheon Rivers revealed significant values (p < 0.001) ranging from 0.013 to 0.014. In addition, the closest genetic distance (0.026) was observed between UN and LN, while the greatest distance (0.087) was found between UN and DC. Analysis of gene flow rates among the fish examined indicated asymmetrical gene exchange within the Nam River, which was 31.51% in the downstream direction (from UN to LN), with a minimal gene flow rate (0.41%) in the upstream (from LN to UN) direction. The opposite trend was recorded between DC and LN, with a higher gene flow rate (29.74%) in the upstream direction compared to the downstream direction (0.12%). Our study highlighted the importance of implementing long-term conservation efforts focused on maintaining river integrity by removing water barriers such as weirs that impede fish migration and implementing active protection measures, such as aquaculture breeding and reasonable stocking practices, to preserve M. rapidus in the study area.

Population structure and genetic diversity of the endangered fish black shinner Pseudopungtungia nigra (Cyprinidae) in Korea: a wild and restoration population.

The black shinner Pseudopungtungia nigra Mori, 1935 is an endangered fish endemic to Korea. It lives in the narrow basin of the Geumgang River, Mangyeonggang River, and Ungcheoncheon Stream, which flow into the West Sea of Korea. One population of P. nigra in Ungcheoncheon Stream has been locally exterminated once; it is now inhabiting the upper reaches of the dam through a restoration program. Efforts to identify and understand the genetic structure of these populations are important for conservation planning. Here, we analyzed genetic diversity using 21 microsatellite markers for 9 populations. The mean number of alleles ranged from 4.4 to 8.1, mean allelic richness ranged from 4.6 to 7.8, mean observed heterozygosity ranged from 0.519 to 0.702, and mean expected heterozygosity ranged from 0.540 to 0.763. All groups had recent and historical bottlenecks (P < 0.05, M-ratio < 0.68). Three groups [YD (2019), OC and UC] had significant inbreeding index values, suggesting that they were engaged in inbreeding. We observed a moderate level of genetic differentiation between MG and the rest of the population (FST = 0.135 to 0.168, P < 0.05). The genetic structure exhibited a fitting constant K = 2, along with separation between MG and the remaining populations. With respect to genetic flow, YD (2019), OC, CG, and ND shifted to the UC population (0.263 to 0.278). The genetic flow of each population was transferred only within the population; there was no gene flow among populations, except for the Ungcheoncheon Stream population. This study shows that the Ungcheoncheon Stream population needs conservation efforts to increase its genetic diversity, and the Geumgang River populations needs a conservation plan that considers the possibility of conservation and evolution through gene exchange among the populations.

The complete mitochondrial genome of Acanthogobius lactipes and its phylogenetic analysis.

Acanthogobius lactipes is a demersal, euryhaline fish belonging to the suborder Gobiodei. This study sequenced and described the complete mitochondrial genome of A. lactipes for the first time. The circular genome of A. lactipes is 16,592 bp in length and contains 13 protein-coding genes, 22 transfer RNA genes, two ribosomal RNA genes, and a control region. The overall A, C, G, and T contents were 27.78, 27.31, 17.52, and 27.39%, respectively. Based on the 13 protein-coding genes, the phylogenetic tree showed that A. lactipes formed a well-supported cluster with the genus Acanthogobius and rooted with other family Oxudercidae species.

The complete mitochondrial genome of Buccinum bayani (Gastropoda: Buccininae) in Korea.

This study is the first to report the complete 15,262 base pair mitochondrial genome of Buccinum bayani, consisting of 13 protein-coding genes, two ribosomal RNA genes, 22 transfer RNA genes, and a control region (D-loop). The overall base composition of the complete genome is A (29.87%), T (39.11%), G (15.86%), and C (15.16%), with a high AT content of 68.98%. Phylogenetic analysis showed that B. bayani was most closely related to B. undatum. The mitogenome of B. bayani will provide helpful information to further our phylogenetic and evolutionary understanding of the family Buccininae.

Phylogeography of the Korean endemic Coreoleuciscus (Cypriniformes: Gobionidae): the genetic evidence of colonization through Eurasian continent to the Korean Peninsula during Late Plio-Pleistocene.

BACKGROUND: Freshwater endemism is thought to have been formed through the vicariance of connected water systems or the process by which ancestral populations colonized specific areas. The Korean Peninsula is well recognized for its high level of freshwater endemism with about 40% of freshwater fish species being endemic. OBJECTIVE: In this study, we attempted to reconstruct the process of speciation and phylogenetic dispersal of Coreoleuciscus species, which is endemic in the Korean Peninsula. METHODS: We used fossil-calibrated divergence time estimation and ancestral distributional reconstruction to infer phylogeographic reconstruction of Coreoleuciscus based on mitochondrial cytochrome c oxidate subunit I (COI) sequences (1551 bp). RESULTS: Our phylogeographic analysis based on a total of 626 individuals revealed that the two Coreoleuciscus species have originated from the independent colonization of different lineages in the ancestral populations, probably during the Late Plio-Pleistocene. The full-scale expansion of Coreoleuciscus populations appears to have taken place after major river structures were completed on the Korean Peninsula. We also provided evidence that the common ancestors of Coreoleuciscus was distributed in Eastern Eurasian continent and subsequently dispersed into the tip of East Asia. High genetic diversity was mainly concentrated in large drainage populations, while small populations showed an monomorphism, which could give important implications for planning the conservation and management of Coreoleuciscus. CONCLUSIONS: The phylogenetic background of the rheophilic Coreoleuciscus species can be explained by the colonizer hypothesis that the endemic freshwater fish originated from the common ancestor in continental region.

The complete mitochondrial genome of the endangered freshwater fish Odontobutis obscurus from Korea.

We report the first complete mitochondrial genome of Odontobutis obscurus, which consists of 17,038 bp harboring 13 protein-coding genes, two ribosomal RNA genes, 22 transfer RNA genes, and a control region (D-loop). The overall base composition of the complete genome is A (30.63%), C (28.72%), T (25.70%), G (14.95%). The complete mitogenome of Odontobutis obscurus, most closely related to congeners in the Bayesian inference and maximum likelihood tree, provides a better understanding of the phylogeny of the genus Odontobutis.

The complete mitochondrial genome of the freshwater fish Opsariichthys uncirostris amurensis from Korea.

We present the first report of the complete mitochondrial genome of Opsariichthys uncirostris amurensis, which consists of 16,613 base pairs harboring 13 protein-coding genes, two ribosomal RNA genes, 22 transfer RNA genes, and a control region (D-loop). The overall base composition of the complete genome is A (27.15%), C (27.15%), T (26.77%), G (18.92%). The complete mitogenome of O. uncirostris amurensis, which was most closely related to O. bidens in the Bayesian inference tree, provides a better understanding of the phylogeny of the genus Opsariichthys.

Complete mitochondrial genome for the whitemouth croaker Micropogonias furnieri (Perciformes: Sciaenidae).

This study is the first to research to report the complete 16,496 bp mitochondrial genome of Micropogonias furnieri, which consists of 13 protein-coding genes, two ribosomal RNA genes, 22 transfer RNA genes, and a control region (D-loop). The overall base composition of the complete genome is 27.26% A, 25.65% T, 16.46% G, and 30.63% C, with a high A + T content of 52.91%. Phylogenetic analysis showed that M. furnieri was most closely related to Sciaenops ocellatus. In this study, the mitogenome of M. furnieri will provide useful information for phylogenetic and evolutionary understanding in the family Sciaenidae.

Complete mitochondrial DNA sequence of Norwegian skates (Raja brachyuran Lafont, 1871) imported to Korea.

In this study, the complete mitochondrial genome of Norwegian skates imported to Korea was sequenced with a circular molecule of 17,121 bp, which consisted of 13 protein-coding genes (PCGs), 2 ribosomal RNAs, 22 transfer RNA genes, and a control region (D-loop). And among these sequences, 193 bp sequence in the D-loop of the genus Raja suggested the possibility of being used as a genetic marker for classification of Raja and Dipturus species. The BI phylogenetic tree by using the nucleotide sequences of 13 PCGs from 15 available mitogenomes of family Rajidae confirmed also that Norwegian skates imported to Korea form a group with Raja brachyura species with high branch value, and that this was a species of Raja brachyura. As above, these results would be expected to provide for the further understanding on the phylogenetic relationship, taxonomic classification and phylogeography of the family Rajidae.

The complete mitochondrial genome of the endangered freshwater fish Kichulchoia brevifasciata in Korea.

Kichulchoia brevifasciata is an endangered fish that is distributed across the Goheung Peninsula, South Korea. This is the first report of the complete mitochondrial genome of K. brevifasciata, which consists of 16,646 bp with 13 protein-coding genes, 2 ribosomal RNA genes, 22 transfer RNA genes, and a control region (D-loop). The overall base composition of the complete genome is A (29.57%), T (28.08%), G (16.54%), and C (25.80%), with a high A + T content of 57.65%. Phylogenetic analysis showed that K. brevifasciata was most closely related to K. multifasciatas.

The complete mitochondrial genome of the hybrid species Pungtungia herzi (♀) × Pseudopungtungia nigra (♂) from Korea.

This study reports the complete mitochondrial genome of a Pungtungia herzi (♀) × Pseudopungtungia nigra (♂) hybrid. The P. herzi (♀) × P. nigra (♂) mitochondrial genome consists of 16,601 bp with 13 protein-coding genes, 2 ribosomal RNA genes, 22 transfer RNA genes, and a control region (D-loop). The overall base composition of the complete mitochondrial genome is 29.99% A, 26.97% T, 17.11% G, and 25.92% C. In the phylogenetic tree, P. herzi (♀) × P. nigra (♂) is closer to P. herzi than to P. nigra. Obtaining the complete mitogenome of P. herzi (♀) × P. nigra (♂) will provide useful data regarding P. herzi and P. nigra conservation and evolution.

The complete mitochondrial genome of Sardinella zunasi (Clupeiformes: Clupeidae).

The complete mitogenome of Sardinella zunasi was determined by next-generation sequencing. The S. zunasi mitogenome was a circular 16,307 bp molecule that contained 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes, and one control region (D-loop). The gene arrangement was consistent with other Sardinella mitogenomes. The phylogenetic relationships of 29 Clupeoidei species based on 13 protein-coding genes from the available mitogenomes were analyzed. Sardinella zunasi clustered with Sardinella among Clupeidae, suggesting a closer relationship with this genus. These results will be useful for understanding the phylogenetic relationships, taxonomic classification, and phylogeography of the genus Sardinella relative to other genera of Clupeoidei.

Complete mitochondrial genome of the Korean endemic species Coreoleuciscus aeruginos holotype from Korea (Cypriniformes, Cyprinidae).

This study is the first to research report the complete 16,563 bp mitochondrial genome of Coreoleuciscus aeruginos, which consists of 13 protein-coding genes (PCGs), 2 ribosomal RNA (rRNA) genes, 22 transfer RNA (tRNA) genes, and a control region (D-loop). The overall base composition of the complete genome is 31.0% A, 28.04% T, 16.27% G, and 24.69% C, with a high A + T content of 59.04%. According to our phylogenetic analysis, C. aeruginos is most closely related to Coreoleuciscus splendidus.

Complete mitochondrial genome of the hybrid grouper Hyporthodus septemfasciatus (♀)×Epinephelus moara (♂) (Perciformes, Serranidae) and results of a phylogenetic analysis.

The complete mitochondrial genome of the hybrid grouper Hyporthodus septemfasciatus (♀)×Epinephelus moara (♂) was obtained by next-generation sequencing. The mitochondrial genome was 16,499 bp long, consisting of 13 protein-coding genes, 22 transfer RNA genes, two ribosomal RNA genes, and a control region (D-loop). The overall base composition is 28.62% A, 28.27% C, 16.27% G, and 26.84% T with 55.46% A + T. In the maximum-likelihood (ML) phylogenetic analysis, the hybrid grouper belonged to the same clade as H. septemfasciatus (maternal inheritance).

Complete mitochondrial genome of the endangered freshwater fish Microphysogobio rapidus (Cypriniformes, Cyprinidae) from Korea.

Microphysogobio rapidus is an endangered freshwater fish from Korea with a limited distribution in the Nakdong River. Here, we determined the mitochondrial genome of M. rapidus, which consisted of 16,603 bp with 13 protein-coding genes, 2 ribosomal RNAs, 22 transfer RNA genes, and a control region (D-loop). The overall base composition of the complete genome was 29.96% A, 26.06% T, 17.24% G, and 26.74% C, with high A + T content of 56.02%.

Complete mitochondrial genome of Halocynthia hilgendorfi ritteri (Pyuridae) from Korea.

Halocynthia hilgendorfi ritteri is an ascidian distributed on the coast of Geoje Island in Korea and found on rocks. The mitochondrial genome of Halocynthia hilgendorfi ritteri consists of 15,181 bp with 13 protein-coding genes, 2 ribosomal RNAs, 23 transfer RNA genes. The overall base composition of the complete genome is 22.94% A, 43.32% T, 25.72% G, and 8.02% C, with a high A + T content of 66.26%.

Genetic diversity and population structure of the endangered fish Pseudobagrus brevicorpus (Bagridae) using a newly developed 12-microsatellite marker.

BACKGROUND: Pseudobagrus brevicorpus is an endangered species in Korea. The development of genetic markers and genetic information regarding the populations of this species are needed to establish conservation strategies. OBJECTIVE: As part of the conservation of P. brevicorpus, a 12-microsatellite marker was developed using next-generation sequencing (NGS) to provide current genetic population information. METHODS: Microsatellites from P. brevicorpus were identified by NGS analysis. Genetic diversity and genetic structure analysis of six populations (Seojeong Stream [SJ], Gokgang Stream [GK], Jaho Stream [JH], Daega Stream [DG], Nam River [NG], and Deokcheon River [DC]) of P. brevicorpus were conducted using the newly developed microsatellite marker. RESULTS: NGS generated 10,347,578 reads and identified 659,507 simple sequence repeats. Twelve microsatellites were successfully amplified and verified in 30 individuals of P. brevicorpus. The genetic diversity of the six P. brevicorpus populations in terms of the number of alleles ranged from 3.667 to 7.111. All populations except DG deviated significantly from Hardy-Weinberg equilibrium (HWE) at one or more loci. The genetic distances of the six populations showed the closest relationship between the SJ and GK populations (independent Stream populations), and there was a close relationship with the JH population among the Nakdong River. Structure analysis showed that P. brevicorpus is largely divided into two groups. CONCLUSIONS: The developed microsatellite marker will be used to provide basic genetic data of P. brevicorpus. Genetic diversity and structure analysis of the population will provide useful information for conservation management of P. brevicorpus.

Complete mitochondrial genome of the hybrid grouper Hyporthodus septemfasciatus (♀) × Epinephelus lanceolatus (♂).

The complete mitochondrial genome of the novel hybrid grouper (Hyporthodus septemfasciatus ♀ × Epinephelus lanceolatus ♂) includes 13 protein-coding genes, 2 ribosomal RNAs, 22 transfer RNA genes, and 1 control region (D-loop) for a total length of 16,559 bp. The overall nucleotide composition encoded on the heavy strand comprises 28.64% A, 28.26% C, 16.26% G, and 26.84% T.

The complete mitochondrial genome of the hybrid grouper Epinephelus fuscoguttatus (♀) × E. polyphekadion (♂).

This study determined the complete mitochondrial genome of the hybrid grouper Epinephelus fuscoguttatus ♀ × E. polyphekadion ♂. The complete mitochondrial genome is 16,648 bp and includes 13 protein-coding, 2 ribosomal RNA, 22 transfer RNA genes, and a control region (D-loop). The nucleotide composition of the L-strand was A 29.12%, C 28.33%, G 15.65%, and T 26.90%. All except the NADH dehydrogenase subunit (ND6) and eight tRNA genes are encoded on the H-strand.