Endangered Schizothoracin Fish in the Tarim River Basin Are Threatened by Introgressive Hybridization
Big-head Schizothoracin (<i>Aspiorhynchus laticeps</i>) and Tarim Schizothoracin (<i>Schizothorax biddulphi</i>) are locally sympatric in the Tarim River Basin. Although another Schizothoracin (<i>Schizothorax esocinus</i>) in Tarim River basin has been speculated...
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MDPI AG
2022-06-01
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| author | Lei Cheng Dan Song Xiaoli Yu Xue Du Tangbin Huo |
| author_facet | Lei Cheng Dan Song Xiaoli Yu Xue Du Tangbin Huo |
| author_sort | Lei Cheng |
| collection | DOAJ |
| description | Big-head Schizothoracin (<i>Aspiorhynchus laticeps</i>) and Tarim Schizothoracin (<i>Schizothorax biddulphi</i>) are locally sympatric in the Tarim River Basin. Although another Schizothoracin (<i>Schizothorax esocinus</i>) in Tarim River basin has been speculated to be hybrid offspring of Big-head Schizothoracin and Tarim Schizothoracin, there was no genetic evidence. Previous studies on the genetics and evolution of Schizothoracins in Xinjiang Province were mostly based on mitochondrial DNA (mtDNA), whose characteristics of maternal inheritance made it hard to answer the question of whether there was hybridization and introgression between Big-head Schizothoracin and Tarim Schizothoracin. In this study, cytochrome b (<i>cytb</i>) gene of mtDNA and internal transcribed spacer 2 (ITS2) that is encoded by the nuclear genome were genotyped within the entire samples at the same time. Our results confirmed that <i>Schizothorax esocinus</i> was the hybrid offspring of Big-head Schizothoracin and Tarim Schizothoracin. The heterozygous ITS2 genotypes and/or <i>Aspiorhynchus laticeps</i>-like mtDNA were also detected in a subset of samples that should have been identified as pure <i>Schizothorax biddulphi</i> based on morphology. The ITS2 is characterized by multi-copy, concert evolution, and biparental inheritance. Thus, by comparing with mtDNA data, broad-scale bidirectional hybridization and introgression between Big-head Schizothoracin and Tarim Schizothoracin were revealed. Although interspecific hybridization may play a positive role in ecology and evolution, interspecific hybrids could threaten their parental species by the swamping of genetics and demography. As both parents of hybridization are critically endangered fishes, in this case, it is urgently necessary to strengthen the scientific assessment of the risks of the hybrids and the control of the hybridization and introgression between <i>Aspiorhynchus laticeps</i> and <i>Schizothorax biddulphi</i> in the Tarim River Basin. |
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| language | English |
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| publishDate | 2022-06-01 |
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| spelling | doaj.art-7a6e8dc03d204affa9eca7c878a2191a2023-12-03T14:40:22ZengMDPI AGBiology2079-77372022-06-0111798110.3390/biology11070981Endangered Schizothoracin Fish in the Tarim River Basin Are Threatened by Introgressive HybridizationLei Cheng0Dan Song1Xiaoli Yu2Xue Du3Tangbin Huo4Key Laboratory of Freshwater Aquatic Biotechnology and Breeding, Ministry of Agriculture and Rural Affairs, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150070, ChinaKey Laboratory of Freshwater Aquatic Biotechnology and Breeding, Ministry of Agriculture and Rural Affairs, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150070, ChinaKey Laboratory of Freshwater Aquatic Biotechnology and Breeding, Ministry of Agriculture and Rural Affairs, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150070, ChinaKey Laboratory of Freshwater Aquatic Biotechnology and Breeding, Ministry of Agriculture and Rural Affairs, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150070, ChinaKey Laboratory of Freshwater Aquatic Biotechnology and Breeding, Ministry of Agriculture and Rural Affairs, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150070, ChinaBig-head Schizothoracin (<i>Aspiorhynchus laticeps</i>) and Tarim Schizothoracin (<i>Schizothorax biddulphi</i>) are locally sympatric in the Tarim River Basin. Although another Schizothoracin (<i>Schizothorax esocinus</i>) in Tarim River basin has been speculated to be hybrid offspring of Big-head Schizothoracin and Tarim Schizothoracin, there was no genetic evidence. Previous studies on the genetics and evolution of Schizothoracins in Xinjiang Province were mostly based on mitochondrial DNA (mtDNA), whose characteristics of maternal inheritance made it hard to answer the question of whether there was hybridization and introgression between Big-head Schizothoracin and Tarim Schizothoracin. In this study, cytochrome b (<i>cytb</i>) gene of mtDNA and internal transcribed spacer 2 (ITS2) that is encoded by the nuclear genome were genotyped within the entire samples at the same time. Our results confirmed that <i>Schizothorax esocinus</i> was the hybrid offspring of Big-head Schizothoracin and Tarim Schizothoracin. The heterozygous ITS2 genotypes and/or <i>Aspiorhynchus laticeps</i>-like mtDNA were also detected in a subset of samples that should have been identified as pure <i>Schizothorax biddulphi</i> based on morphology. The ITS2 is characterized by multi-copy, concert evolution, and biparental inheritance. Thus, by comparing with mtDNA data, broad-scale bidirectional hybridization and introgression between Big-head Schizothoracin and Tarim Schizothoracin were revealed. Although interspecific hybridization may play a positive role in ecology and evolution, interspecific hybrids could threaten their parental species by the swamping of genetics and demography. As both parents of hybridization are critically endangered fishes, in this case, it is urgently necessary to strengthen the scientific assessment of the risks of the hybrids and the control of the hybridization and introgression between <i>Aspiorhynchus laticeps</i> and <i>Schizothorax biddulphi</i> in the Tarim River Basin.https://www.mdpi.com/2079-7737/11/7/981<i>Aspiorhynchus laticeps</i><i>Schizothorax biddulphi</i><i>Schizothorax esocinus</i>mitochondrial DNA (mtDNA)internal transcribed spacer 2 (ITS2)hybridization |
| spellingShingle | Lei Cheng Dan Song Xiaoli Yu Xue Du Tangbin Huo Endangered Schizothoracin Fish in the Tarim River Basin Are Threatened by Introgressive Hybridization Biology <i>Aspiorhynchus laticeps</i> <i>Schizothorax biddulphi</i> <i>Schizothorax esocinus</i> mitochondrial DNA (mtDNA) internal transcribed spacer 2 (ITS2) hybridization |
| title | Endangered Schizothoracin Fish in the Tarim River Basin Are Threatened by Introgressive Hybridization |
| title_full | Endangered Schizothoracin Fish in the Tarim River Basin Are Threatened by Introgressive Hybridization |
| title_fullStr | Endangered Schizothoracin Fish in the Tarim River Basin Are Threatened by Introgressive Hybridization |
| title_full_unstemmed | Endangered Schizothoracin Fish in the Tarim River Basin Are Threatened by Introgressive Hybridization |
| title_short | Endangered Schizothoracin Fish in the Tarim River Basin Are Threatened by Introgressive Hybridization |
| title_sort | endangered schizothoracin fish in the tarim river basin are threatened by introgressive hybridization |
| topic | <i>Aspiorhynchus laticeps</i> <i>Schizothorax biddulphi</i> <i>Schizothorax esocinus</i> mitochondrial DNA (mtDNA) internal transcribed spacer 2 (ITS2) hybridization |
| url | https://www.mdpi.com/2079-7737/11/7/981 |
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