Phylogeographic structure of the dwarf snakehead (Channa gachua) around Gulf of Tonkin: Historical biogeography and pronounced effects of sea‐level changes

Abstract

Geological events, landscape features, and climate fluctuations have shaped the distribution of genetic diversity and evolutionary history in freshwater fish, but little attention has been paid to that around the Gulf of Tonkin; therefore, we investigated the phylogeographic structure of the dwarf snakehead (Channa gachua) on Hainan Island and mainland China, as well as two populations in Vietnam. We attempted to elucidate the origins of freshwater fish in South Hainan by incorporating genetic data from DNA markers on both the mitochondrial cytochrome b gene (cyt b) and the nuclear recombination‐activating gene 1 (RAG‐1). Mitochondrial phylogenetic analysis identified two major lineages (lineages A and B), which may represent separate species. Divergence data suggested that C. gachua populations diverged between 0.516 and 2.376 myr. The divergence of the two cryptic species is congruent with sea‐level rise, which subsequently isolated Hainan from the mainland. During the Pleistocene glaciations, the entire region of the Gulf of Tonkin and the Qiongzhou Strait became part of the coastal plain of the Asian continent, which might have resulted in the current distribution patterns and dispersal routes of C. gachua populations. The formation of three sublineages in lineage A indicated that the Gulf of Tonkin was a geographical barrier between Hainan Island and mainland China but not between Vietnam and Hainan Island. The results of this study may help to elucidate the origins of freshwater fish in South Hainan and the phylogeographic structure of C. gachua.

Genetic Diversity and Population Structure of Spirobolus bungii as Revealed by Mitochondrial DNA Sequences

“…The results of the millipede phylogenetic analyses appear to be explained by the geological timeframes of the formation of the Yangtze and Yellow rivers. Recent studies have indicated that large geographical barriers have an obvious blocking effect on genetic diversity and gene exchange within populations [ 52 , 53 , 54 ]. At present, the isolation of soil fauna in the Yangtze and Yellow rivers has not been extensively described, but some studies have shown that the Yangtze and Yellow rivers block the gene exchange of some terrestrial animals [ 55 , 56 ].…”

Multilocus Phylogeography and Population Genetic Analyses of Opsariichthys hainanensis Reveal Pleistocene Isolation Followed by High Gene Flow around the Gulf of Tonkin

“…Continental islands, due to their close proximity to neighboring continental areas, provide excellent opportunities for understanding the origin and diversification of freshwater fishes [ 1 ]. During glacial phases, the islands and the mainland were connected by land bridges due to the decrease in sea level.…”

“…Previous studies on the phylogeography of freshwater fishes between the island and mainland have focused on Taiwan and mainland China (e.g., Onychostoma barbatulus [ 3 ]; Squalidus argentatus [ 2 ]; Cobitis sinensis [ 4 ]; Opsariichthys [ 5 ]; Rhodeus ocellatus [ 6 ]; Acrossocheilus paradoxus [ 7 ]). There is relatively little information available on the phylogeography of freshwater fishes between Hainan Island and mainland China (e.g., Garra orientalis [ 8 ]; Aphyocypris normalis [ 9 ]; O. hainanensis [ 10 ]; Channa gachua [ 1 ]).…”

“…The uplift of the continental shelf during the ice age also created many opportunities for water systems to converge in coastal estuaries, and the confluence of water systems also provided opportunities for biological diffusion [ 5 , 8 ] (Lin et al, 2016; Yang et al, 2016). In previous phylogeographic studies of freshwater fishes on Hainan Island, freshwater fishes migrated from mainland China and Vietnam via the Qiongzhou Strait and the Gulf of Tonkin during Pleistocene glaciations [ 1 , 8 ]. During the ice age, the Gulf of Tonkin was exposed because of the drop in sea level, and the entire area, including the Gulf of Tonkin and Hainan Island, became part of the coastal plains of the Asian continent.…”

“…During the ice age, the Gulf of Tonkin was exposed because of the drop in sea level, and the entire area, including the Gulf of Tonkin and Hainan Island, became part of the coastal plains of the Asian continent. The northern water system of Vietnam flows into the South China Sea through the Leizhou Peninsula and the southwestern part of Hainan Island [ 1 , 12 , 13 ]. There are 154 rivers flowing into the sea on Hainan Island, and previous phylogeographic studies have focused on the major river system.…”