Population genetics of swamp eel in the Yangtze River: comparative analyses between mitochondrial and microsatellite data provide novel insights.

The swamp eel (Monopterus albus) is a typical sex reversal fish with high economic value. Several phylogeographic studies have been performed using various markers but comparative research between mitochondrial and nuclear markers is rare. Here, a fine-scale study was performed across six sites along the Yangtze River including three sites on the main stem and three sites from tributaries. A total of 180 swamp eel individuals were collected. Genetic structure and demographic history were explored using data from two mitochondrial genes and eight microsatellite loci. The results revealed the samples from tributary sites formed three separate clades which contained site-specific lineages. Geographic isolation and the habitat patchiness caused by seasonal cutoff were inferred to be the reasons for this differentiation. Strong gene flow was detected among the sites along the main stem. Rapid flow of the river main stem may provide the dynamic for the migration of swamp eel. Interestingly, the comparative analyses between the two marker types was discordant. Mitochondrial results suggested samples from three tributary sites were highly differentiated. However, microsatellite analyses indicated the tributary samples were moderately differentiated. We conclude this discordance is mainly caused by the unique life history of sex reversal fish. Our study provides novel insights regarding the population genetics of sex reversal fish.

The complete mitochondrial genome of Acrossocheilus wenchowensis (Cyprinidae, Barbinae) from Xinanjiang River.

The complete mt genome sequence of Acrossocheilus wenchowensis was obtained by PCR, containing 37 genes with 13 protein coding genes, 22 transfer RNAs (tRNAs), two ribosomal RNAs (rRNAs) and a non-coding control region.

Mitochondrial DNA sequence of the hybrid of Pelteobagrus vachelli (♀) × Pelteobagrus fulvidraco (♂).

The complete mitochondrial genome sequence of a hybrid, which was produced by sexual hybridization of Pelteobagrus vachelli (♀) × Pelteobagrus fulvidraco (♂), was obtained. The complete mitochondrial genome of the hybrid is 16,532 bp, containing 37 genes. 129 Site differences were found in overall length compared with P. vachelli.

The complete mitochondrial genome of Hebesoma violentum (Acanthocephala).

The acanthocephalan Hebesoma violentum Van Cleave was obtained in the intestine of Siniperca chuatsi. The complete mt genome sequence of H. violentum was obtained by long PCR, containing 36 genes with 12 protein coding genes, 22 transfer RNAs (tRNAs), and two ribosomal RNAs (rRNAs).