Three complete mitochondrial genomes of freshwater fishes in the genus Abbottina (Cypriniformes: Gobionidae)

Pleistocene Landscape Dynamics Drives Lineage Divergence of a Temperate Freshwater Fish Gobio rivuloides in Coastal Drainages of Northern China

Understanding historical processes underlying lineage distribution patterns is a primary goal of phylogeography. We selected Gobio rivuloides (Cypriniformes: Gobionidae) as a model to improve our knowledge about how intraspecific genetic divergence of freshwater fishes arises in coastal drainages of northern China via statistical analysis using cytochrome b gene. The time-calibrated phylogeny of G. rivuloides showed the divergence of two major lineages (I and II) at ~0.98 Ma (million years ago). Lineage I can be divided into two sub-lineages (I-A and I-B) with a divergence time of ~0.83 Ma. Sub-lineage I-A inhabits the Amur River, and sub-lineage I-B lives in the Luan River and Liao River. Lineage II is distributed in the Yellow River and Hai River, with close genetic relationships between the two drainages, and can be split into two sub-lineages (II-C and II-D) with a divergence time of ~0.60 Ma. Our findings indicate that the splitting of lineages and sub-lineages could be attributed to geographic isolation caused by the formation of the Bohai Sea, river capture, and the episodic hydrologic closing of a paleolake during the late Lower-Middle Pleistocene. It is also the first report we know of displaying a clear phylogeographic break for freshwater fishes across coastal drainages in northern China.

Phylogeographical Analysis of the Freshwater Gudgeon Huigobio chenhsienensis (Cypriniformes: Gobionidae) in Southern China

The freshwater gudgeon Huigobio chenhsienensis (Cypriniformes: Gobionidae) is a small fish endemic to southern China. In this study, we used mitochondrial cytochrome b gene (Cytb), from wide-ranging samplings of H. chenhsienensis from the Ou River (the central of southern China) to the Yangtze River Basin (the northernmost part of southern China) to explore genetic variations and the evolutionary history of H. chenhsienensis in southern China. In total, 66 haplotypes were identified from Cytb sequences of 142 H. chenhsienensis individuals, which could be divided into lineages A, B, and C with divergence times of ~4.24 Ma and ~3.03 Ma. Lineage A was distributed in the lower reaches of the Yangtze River, the Oujiang River, and the Jiao River, lineage B was distributed in the Qiantang River and the Cao'e River, whereas lineage C was restricted to the Poyang Lake drainage from the middle reaches of the Yangtze River. Lineage A could be subdivided into sub-lineages A-I, A-II, A-III, and A-IV, with divergence times of 1.30, 0.97, and 0.44 Ma. Lineage C could be subdivided into sub-lineages C-I and C-II, with a divergence time of 0.85 Ma. Our findings indicate that climate change during the Pliocene and Pleistocene eras, as well as the limited dispersal ability of H. chenhsienensis, have been major drivers for shaping the phylogeographical patterns of H. chenhsienensis.

Three mitochondrial genomes of freshwater fishes in the genus Squalidus (Cypriniformes: Gobionidae)

Mitochondrial genomes of Squalidus mantschuricus, S. chankaensis, and S. longifilis have been determined using Sanger sequencing (GenBank Accession No. MT767745-MT767747). The three mitochondrial genomes consist of 13 protein-coding genes, two rRNA genes, 22 tRNA genes, and one control region with the length of 16,605, 16,611, and 16,607 bp. Phylogenetic analysis of the three species showed that S. mantschuricus is nested within a fully supported terminal clade with S. argentatus, and S. chankaensis is a sister group of S. mantschuricus, S. argentatus, and S. wolterstorffi. Squalidus longifilis is positioned in a clade with S. multimaculatus and S. gracilis.

Two mitochondrial genomes of freshwater gudgeons in the genus Gobio (Cypriniformes: Gobionidae)

Two complete mitochondrial genomes of Gobio acutipinnatus and G. microcephalus are assembled, and they have the same length with slightly high A + T contents (54.88% and 56.57%) in base compositions. Results in the reconstructed phylogeny show that the genus Gobio is a monophyletic group, and it is a sister taxon of the genus Romanogibio.