Abstract
Phylogeographical analyses on Squalidus argentatus samples from thirteen localities within mainland China and Taiwan were conducted for biogeographic studies, as their dispersal strictly depends on geological evolution of the landmasses. A total of 95 haplotypes were genotyped for mtDNA cyt b gene in 160 specimens from nine river systems. Relatively high levels of haplotype diversity (h = 0.984) and low levels of nucleotide diversity (π = 0.020) were detected in S. argentatus. Two major phylogenetic haplotype groups, A and B, were revealed via phylogenetic analysis. The degree of intergroup divergence (3.96%) indicates that these groups diverged about 4.55 myr (million years) ago. Haplotype network and population analyses indicated significant genetic structure (FST = 0.775), largely concordant with the geographical location of the populations. According to SAMOVA analysis, we divided these populations into four units: Yangtze-Pearl, Qiantang-Minjiang, Jiulong-Beijiang and Taiwan groups. Mismatch distribution analysis, neutrality tests and Bayesian skyline plots indicated a significant population expansion for lineage A and B, approximately dated 0.35 and 0.04 myr ago, respectively. We found strong geographical organization of the haplotype clades across different geographic scales that can be explained by episodes of dispersal and population expansion followed by population fragmentation and restricted gene flow.
Highlights
The Cyprinidae represent one of the most diverse freshwater fish groups and are a major component of the primary freshwater fish fauna of Africa, Eurasia and North America, comprising more than 220 genera and 2400 species [1]
Our results show that S. argentatus has a high level of genetic structuring, which is similar to many other widespread freshwater fishes observed in this region of southern China, such as
We suggest that four regions identified by SAMOVA should be regarded as different Management Units (MUs), conforming to the major zoological regions of mainland China and Taiwan
Summary
The Cyprinidae represent one of the most diverse freshwater fish groups and are a major component of the primary freshwater fish fauna of Africa, Eurasia and North America, comprising more than 220 genera and 2400 species [1]. Among the distribution of the Cyprinidae, China constitutes a vast area with remarkably high diversity, amounting to a total of more than 750 species [2]. The Southern China District, including areas south of the Yangtze River and the South China Sea archipelagos, is well known for its highly diverse ecosystems and habitats, where the present distribution of freshwater species has been greatly influenced by past geological and hydrological events [3]. Many studies have explored the biogeography of southern China, and have described vicariant events that resulted in subsequent differentiation in salamanders [4], frogs [5], fishes [6], and birds [7]. Studies dealing with freshwater taxa that are distributed in the east of the WuYi Mountains are scarce [6,8,9,10,11,12]
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