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Genetic diversity and evolutionary history of the Schizothorax species complex in the Lancang River (upper Mekong)

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ABSTRACT

The genus Schizothorax (Cyprinidae), one of the most diverse genera of ichthyofauna of the Qinghai‐Tibetan Plateau (QTP), is a good candidate for investigating patterns of genetic variation and evolutionary mechanisms. In this study, sequences from the mitochondrial control region, the cytochrome b gene, and two nuclear genes were used to re‐examine the genetic diversity and investigate the evolutionary history of the Schizothorax species complex inhabiting the Lancang River. Three maternal clades were detected in the Schizothorax species complex, but frequent nuclear allele sharing also occurred among the three maternal clades. A discrepancy between topologies of mitochondrial and nuclear loci might result from introgression or/and incomplete lineage sorting. The divergence of the clades of the Schizothorax species complex was closely related to the Late Pliocene and Early Pleistocene orogenesis of the QTP and Southwest Mountains of China. Demographic analyses indicated that the species complex subsequently persisted in situ with stable populations during Pleistocene glacial cycling, which suggested that Pleistocene climate changes did not exert a remarkable influence on the species complex. Our study provides a comprehensive analysis of the genetic diversity and evolutionary history of the Schizothorax species complex in the Lancang River.

No MeSH data available.


A representative organism of the Schizothorax species in the Lancang River.
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ece32319-fig-0001: A representative organism of the Schizothorax species in the Lancang River.

Mentions: The schizothoracine (Cyprinidae) fishes, representing the largest and most diverse taxon of the QTP ichthyofauna, exhibit exquisite adaptations to the rigorous conditions of the plateau (Wu and Wu 1992; Thompson et al. 2000; Bickler and Buck 2007). These fishes extensively dominate the torrential mountain streams and plateau lakes of the QTP, and the peripheral regions of the QTP (Cao et al. 1981; Chen and Cao 2000). The genus Schizothorax is one of the most diversified of the schizothoracines, comprising numerous species, and subspecies (Chen and Cao 2000). Five closely related Schizothorax species or subspecies (S. lantsangensis, S. lissolabiatus, S. nudiventris, S. yunnanensis taliensis and S. yunnanensis yunnanensis; Fig. 1) have been reported in the Lancang River basin. Compared with the broad distribution of S. lissolabiatus and S. y. yunnanensis, S. lantsangensis, and S. nudiventris only inhabit the main stream (Chen and Cao 2000; Chen 2013). Owing to human activities, S. yunnanensis taliensis has been reported to be near extinction and is rarely recorded in Erhai Lake (Chen 2013). Furthermore, Schizothorax dolichonema was previously reported to occur only in the Jinsha River (Upper Yangtze River), but this species has recently been noted in the upper Lancang River (Chen 2013). However, S. dolichonema is phylogenetically more closely related to the Jinsha River species complex than to the Lancang River species complex (Qi et al. 2012). The Schizothorax species complex in the Lancang River is an informative candidate for the study of the effects of the complex geological movements and Pleistocene glacial cycles on fish species on the QTP and in China's Southwest Mountainous Region.


Genetic diversity and evolutionary history of the Schizothorax species complex in the Lancang River (upper Mekong)
A representative organism of the Schizothorax species in the Lancang River.
© Copyright Policy - creativeCommonsBy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5016629&req=5

ece32319-fig-0001: A representative organism of the Schizothorax species in the Lancang River.
Mentions: The schizothoracine (Cyprinidae) fishes, representing the largest and most diverse taxon of the QTP ichthyofauna, exhibit exquisite adaptations to the rigorous conditions of the plateau (Wu and Wu 1992; Thompson et al. 2000; Bickler and Buck 2007). These fishes extensively dominate the torrential mountain streams and plateau lakes of the QTP, and the peripheral regions of the QTP (Cao et al. 1981; Chen and Cao 2000). The genus Schizothorax is one of the most diversified of the schizothoracines, comprising numerous species, and subspecies (Chen and Cao 2000). Five closely related Schizothorax species or subspecies (S. lantsangensis, S. lissolabiatus, S. nudiventris, S. yunnanensis taliensis and S. yunnanensis yunnanensis; Fig. 1) have been reported in the Lancang River basin. Compared with the broad distribution of S. lissolabiatus and S. y. yunnanensis, S. lantsangensis, and S. nudiventris only inhabit the main stream (Chen and Cao 2000; Chen 2013). Owing to human activities, S. yunnanensis taliensis has been reported to be near extinction and is rarely recorded in Erhai Lake (Chen 2013). Furthermore, Schizothorax dolichonema was previously reported to occur only in the Jinsha River (Upper Yangtze River), but this species has recently been noted in the upper Lancang River (Chen 2013). However, S. dolichonema is phylogenetically more closely related to the Jinsha River species complex than to the Lancang River species complex (Qi et al. 2012). The Schizothorax species complex in the Lancang River is an informative candidate for the study of the effects of the complex geological movements and Pleistocene glacial cycles on fish species on the QTP and in China's Southwest Mountainous Region.

View Article: PubMed Central - PubMed

ABSTRACT

The genus Schizothorax (Cyprinidae), one of the most diverse genera of ichthyofauna of the Qinghai‐Tibetan Plateau (QTP), is a good candidate for investigating patterns of genetic variation and evolutionary mechanisms. In this study, sequences from the mitochondrial control region, the cytochrome b gene, and two nuclear genes were used to re‐examine the genetic diversity and investigate the evolutionary history of the Schizothorax species complex inhabiting the Lancang River. Three maternal clades were detected in the Schizothorax species complex, but frequent nuclear allele sharing also occurred among the three maternal clades. A discrepancy between topologies of mitochondrial and nuclear loci might result from introgression or/and incomplete lineage sorting. The divergence of the clades of the Schizothorax species complex was closely related to the Late Pliocene and Early Pleistocene orogenesis of the QTP and Southwest Mountains of China. Demographic analyses indicated that the species complex subsequently persisted in situ with stable populations during Pleistocene glacial cycling, which suggested that Pleistocene climate changes did not exert a remarkable influence on the species complex. Our study provides a comprehensive analysis of the genetic diversity and evolutionary history of the Schizothorax species complex in the Lancang River.

No MeSH data available.