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

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.

Historical Landscape Evolution Shaped the Phylogeography and Population History of the Cyprinid Fishes of Acrossocheilus (Cypriniformes: Cyprinidae) According to Mitochondrial DNA in Zhejiang Province, China

Geological events and landscape features, as well as changes in the climate during the Pliocene period, have shaped the distribution of genetic diversity and demographic history of freshwater fish in mainland China. In this study, we investigated the phylogeny and population genetic structure of Acrossocheilus species (A. fasciatus, A. kreyenbergii and A. wenchowensis) in the Zhejiang region by the mitochondrial cytochrome b (cyt-b) and control (D-loop) region s. Mitochondrial phylogenetic analysis revealed three major lineages (lineages A, B and C), which may represent A. fasciatus, A. wenchowensis and A. kreyenbergii, respectively. Our results revealed that A. fasciatus and A. wenchowensis diverged from A. kreyenbergii in the Zhejiang region. The uplift of the Wuyi Mountains and the Xianxia Mountains served as an important geographic barrier in the diversification of the three Acrossocheilus species. The most recent common ancestors (TMRCAs) of the three lineages and lineages A + B were dated to 1.859 and 1.614 myr, respectively. Our results indicate that the effective population sizes of A. fasciatus and A. wenchowensis remained constant from the past to the present, as supported by ABC analysis. For conservation and protection, a strategy is required because of their genetic uniqueness, and we suggest that the two regions divided by the Xianxia Mountains be regarded as different management units (Mus), conforming to the major zoological regions of the Zhejiang region.

The role of landscape evolution in the genetic diversification of a stream fish Sarcocheilichthys parvus from Southern China

Sarcocheilichthys parvus (Cypriniformes: Gobionidae) is a stream fish which is endemic to sub-tropical coastal drainages in southern China, thus offering a valuable model for understanding how genetic divergence arises in stream-adapting freshwater fishes in this region. Using the mitochondrial Cyt b gene, integrative analyses of phylogeny, population demography, and ancestral area and paleo-drainage reconstructions are carried out to explicitly explore the role of landscape evolution in genetic diversification of S. parvus. The time-calibrated phylogeny of S. parvus indicates the splitting of two major lineages (A and B) at ∼3.66 Ma. Lineage A inhabits the Poyang Lake sub-drainage of the middle Yangtze River, Han River and Pearl River, and can be split into two sub-lineages (A-I and A-II), where sub-lineage A-II can be further sub-divided into three infra-sub-lineages (A-IIa, A-IIb and A-IIc). Except for the infra-sub-lineage A-IIc, which is restricted to the Han River and Pearl River, the other sub-lineages and infra-sub-lineages live exclusively in the Poyang Lake sub-drainage. Lineage B lives in the lower Yangtze River, Qiantang River, Jiaojiang River and Ou River, displaying close genetic relationships among the drainages. Rapid population expansion has occurred since the Late Pleistocene. Our findings indicate that the splitting of lineages A and B could be attributed to geographic isolation due to the Zhe-Min Uplift, acting as a biogeographic barrier before the late Early Pleistocene. Furthermore, the strong genetic divergence within Lineage A could be explained by the isolation role of the Nanling Mountains and Poyang Lake acting as an ecological barrier; while the lack of phylogenetic structure within Lineage B may have been the result of paleo-drainage connections or episodic freshwater connections during the eustatic low stand of sea level in the late Middle-Late Pleistocene.