The effect of total dissolved gas （TDG） supersaturation on fish living downstream of dams is one of the main ecological risks of high dam construction. A strategy for mitigating the negative effects is needed urgent...The effect of total dissolved gas （TDG） supersaturation on fish living downstream of dams is one of the main ecological risks of high dam construction. A strategy for mitigating the negative effects is needed urgently since many high dams are under construction in the upper reaches of the Yangtze River in China. Experiments on the hatching process of David＇s schizothoracin were carried out and the results show that the hatching rate decreased with increasing TDG levels, and that most eggs hatched within a very short time in the higher TDG saturation groups. By using a stereomicroscope, damages to the head, yolk sac, body, anus, etc. were found in larvae which hatched in TDG supersaturated water. Results show that the lesion rate increased with increasing TDG levels. Furthermore, 7-d-old David＇s schizothoracin were exposed to TDG supersaturated water levels of 100%, 105%, 110%, 115%, 120%, 125%, 130%, 135%, and 140% for testing their tolerance to TDG supersaturation. We found that the median lethal concentrations （LC50） for 13, 14, 20, 35, 52, 73, and 96 h exposure were 138%, 138%, 134%, 130%, 129%, 128%, and 126%, respectively. The median lethal times （LTs0） were 7.49, 11.04, 19.25, and 35.38 h for exposure to water with TDG levels of 145%, 140%, 135%, and 130%, respectively.展开更多
Schizothoracine fishes are distributed in the Nagqu region,which is the hinterland of the Tibetan Plateau.They have adapted to the cold and strongly ultraviolet environment of the plateau and show diverse morphologies...Schizothoracine fishes are distributed in the Nagqu region,which is the hinterland of the Tibetan Plateau.They have adapted to the cold and strongly ultraviolet environment of the plateau and show diverse morphologies,which makes them ideal for studying the relationship between phenotype and environment.However,traditional morphological measurements are time consuming and labor costly.In this study,we propose a deep-learningbased method for acquiring high-throughput phenotypic data of fishes,including image dataset construction of schizothoracine fishes(including front,side,and top views),fish keypoint detection based on the You Only Look Once(YOLO)model,and reconstruction of 2D and 3D keypoint coordinates based on multiple views.A total of 7050 phenotypic data points consisting of keypoint distances and angles were constructed for each fish and were highly correlated(>0.98)with the corresponding data measured manually.We obtained phenotypic data for a total of 525 fishes from three schizothoracine fish groups inhabiting riverine,lacustrine,and river–lake transitional environments using the proposed phenotypic data acquisition method.We employed a random forest algorithm to classify the groups,achieving a classification accuracy of 96%,and identified 15 morphometric indices that exhibited statistically significant differences.,of which 6 were related to head morphology,6 related to body shape,and 3 related to tail morphology,based on the random forest algorithm.Specifically,river-living schizothoracine fishes showed a blunt head,robust body,and elongated caudal peduncle which may reflect adaptations to the turbulence of the river,while the lake-living schizothoracine fishes have the opposite effect.Schizothoracine fishes at the river–lake transitional zones were phenotypically characterized as being in the middle of the two phenotypes,and these presumably reflect adaptations to their lake habitat.This study provides a methodological reference for obtaining high-throughput phenotypic data on fish and a theoretical basis for understanding the adaptation of very high-altitude schizothoracine fishes to their environment.展开更多
Fishes harbor a huge resource of phenotypic diversity and are useful for understanding the genetic basis of morphological variation.However,it is difficult to transfer classical genetic mapping to most non-model speci...Fishes harbor a huge resource of phenotypic diversity and are useful for understanding the genetic basis of morphological variation.However,it is difficult to transfer classical genetic mapping to most non-model species.In this study,we performed a comparative sequence analysis of Fgfr1a to first interpret the evolution of this candidate scale-loss gene in 15 schizothoracine fishes with various scale phenotypes.While considerable amino acid(AA)substitutions were observed,molecular evolution analysis indicates that the overall coding regions were subject to functional constraint.We also identified extra copies of Fgfr1a in 4 scale-loss fishes and detected accelerated evolution in one AA substitution specific to these duplicates.We speculate that Fgfr1a had accumulated mutations in the ancestral lineage of scale-loss schizothoracine fishes before experiencing duplication events,which was further followed by the diversification of species.In silico mutation analysis predicted deleterious effects of the mutations while no disruptive molecular mechanism was detected.Collectively,our results highlight the important role of Fgfr1a gene in the adaptive evolution of schizothoracine fishes during their radiation in the Qinghai-Tibetan Plateau.展开更多
We recovered the phylogenetic relationships among 23 species and subspecies of the highly special-ized grade schizothoracine fishes distributing at 36 geographical sites in the Tibetan Plateau and its surrounding regi...We recovered the phylogenetic relationships among 23 species and subspecies of the highly special-ized grade schizothoracine fishes distributing at 36 geographical sites in the Tibetan Plateau and its surrounding regions by analyzing sequences of cytochrome b genes. Furthermore, we estimated the possible divergent times among lineages based on a historical geological isolation event in the Tibetan Plateau. The molecular data revealed that the highly specialized grade schizothoracine fishes were not a monophyletic group, but were the same as genera Gymnocypris and Schizogypsis. Our results indi-cated that the molecular phylogenetic relationships apparently reflected their geographical and historical associations with drainages, namely species from the same and adjacent drainages clustered together and had close relationships. The divergence times of different lineages were well consistent with the rapid uplift phases of the Tibetan Plateau in the late Cenozoic, suggesting that the origin and evolution of schizothoracine fishes were strongly influenced by environment changes resulting from the upheaval of the Tibetan Plateau.展开更多
Molecular phylogeny of three genera containing nine species and subspecies of the specialized schizothoracine fishes are investigated based on the complete nucleotide sequence of mitochondrial cytochrome b gene. Meant...Molecular phylogeny of three genera containing nine species and subspecies of the specialized schizothoracine fishes are investigated based on the complete nucleotide sequence of mitochondrial cytochrome b gene. Meantime relationships between the main cladogenetic events of the specialized schizothoracine fishes and the stepwise uplift of the Qinghai-Tibetan Plateau are also conducted using the molecular clock, which is calibrated by geological isolated events between the upper reaches of the Yellow River and the Qinghai Lake. Results indicated that the specialized schizothoracine fishes are not a monophyly. Five species and subspecies of Ptychobarbus form a monophyly. But three species of Gymnodiptychus do not form a monophyly. Gd.integrigymnatus is a sister taxon of the highly specialized schizothoracine fishes while Gdo pachycheilus has a close relation with Gd. dybowskii, and both of them are as a sister group of Diptychus maculatus. The specialized schizothoracines fishes might have originated during the Miocene(about 10 MaBP), and then the divergence of three genera happened during late Miocene (about 8 MaBP). Their main specialization occurred during the late Pliocene and Pleistocene (3.54-0.42 MaBP). The main cladogenetic events of the specialized schizothoracine fishes are mostly correlated with the geological tectonic events and intensive climate shift happened at 8, 3.6, 2.5 and 1.7 MaBP of the late Cenozoic.Molecular clock data do not support the hypothesis that the Qinghai-Tibetan Plateau uplifted to near present or even higher elevations during the Oligocene or Miocene, and neither in agreement with the view that the plateau uplifting reached only to an altitude of 2000 m during the late Pliocene(about 2.6 MaBP).展开更多
基金Project (No. 50979063) supported by the National Natural Science Foundation of China
文摘The effect of total dissolved gas （TDG） supersaturation on fish living downstream of dams is one of the main ecological risks of high dam construction. A strategy for mitigating the negative effects is needed urgently since many high dams are under construction in the upper reaches of the Yangtze River in China. Experiments on the hatching process of David＇s schizothoracin were carried out and the results show that the hatching rate decreased with increasing TDG levels, and that most eggs hatched within a very short time in the higher TDG saturation groups. By using a stereomicroscope, damages to the head, yolk sac, body, anus, etc. were found in larvae which hatched in TDG supersaturated water. Results show that the lesion rate increased with increasing TDG levels. Furthermore, 7-d-old David＇s schizothoracin were exposed to TDG supersaturated water levels of 100%, 105%, 110%, 115%, 120%, 125%, 130%, 135%, and 140% for testing their tolerance to TDG supersaturation. We found that the median lethal concentrations （LC50） for 13, 14, 20, 35, 52, 73, and 96 h exposure were 138%, 138%, 134%, 130%, 129%, 128%, and 126%, respectively. The median lethal times （LTs0） were 7.49, 11.04, 19.25, and 35.38 h for exposure to water with TDG levels of 145%, 140%, 135%, and 130%, respectively.
基金funded by the National Natural Science Foundation of China(NSFC)Joint Fund Priority Support Program(U23A20249)the“Special fund for youth team of the Southwest University”(SWUXJPY202302)+3 种基金the“National Talent Research Grant for 2023”(5330500953)National Natural Science Foundation of China(32072980)Chongqing Innovation Program for Graduate Research(CYB240106)the National Key R&D Program of China(grant no.2024YFD1200703).
文摘Schizothoracine fishes are distributed in the Nagqu region,which is the hinterland of the Tibetan Plateau.They have adapted to the cold and strongly ultraviolet environment of the plateau and show diverse morphologies,which makes them ideal for studying the relationship between phenotype and environment.However,traditional morphological measurements are time consuming and labor costly.In this study,we propose a deep-learningbased method for acquiring high-throughput phenotypic data of fishes,including image dataset construction of schizothoracine fishes(including front,side,and top views),fish keypoint detection based on the You Only Look Once(YOLO)model,and reconstruction of 2D and 3D keypoint coordinates based on multiple views.A total of 7050 phenotypic data points consisting of keypoint distances and angles were constructed for each fish and were highly correlated(>0.98)with the corresponding data measured manually.We obtained phenotypic data for a total of 525 fishes from three schizothoracine fish groups inhabiting riverine,lacustrine,and river–lake transitional environments using the proposed phenotypic data acquisition method.We employed a random forest algorithm to classify the groups,achieving a classification accuracy of 96%,and identified 15 morphometric indices that exhibited statistically significant differences.,of which 6 were related to head morphology,6 related to body shape,and 3 related to tail morphology,based on the random forest algorithm.Specifically,river-living schizothoracine fishes showed a blunt head,robust body,and elongated caudal peduncle which may reflect adaptations to the turbulence of the river,while the lake-living schizothoracine fishes have the opposite effect.Schizothoracine fishes at the river–lake transitional zones were phenotypically characterized as being in the middle of the two phenotypes,and these presumably reflect adaptations to their lake habitat.This study provides a methodological reference for obtaining high-throughput phenotypic data on fish and a theoretical basis for understanding the adaptation of very high-altitude schizothoracine fishes to their environment.
基金supported by the grants from the Knowledge Innovation Project(KSCX2-EW-J-26)Youth Innovation Promotion Association Foundation of the Chinese Academy of Sciences.
文摘Fishes harbor a huge resource of phenotypic diversity and are useful for understanding the genetic basis of morphological variation.However,it is difficult to transfer classical genetic mapping to most non-model species.In this study,we performed a comparative sequence analysis of Fgfr1a to first interpret the evolution of this candidate scale-loss gene in 15 schizothoracine fishes with various scale phenotypes.While considerable amino acid(AA)substitutions were observed,molecular evolution analysis indicates that the overall coding regions were subject to functional constraint.We also identified extra copies of Fgfr1a in 4 scale-loss fishes and detected accelerated evolution in one AA substitution specific to these duplicates.We speculate that Fgfr1a had accumulated mutations in the ancestral lineage of scale-loss schizothoracine fishes before experiencing duplication events,which was further followed by the diversification of species.In silico mutation analysis predicted deleterious effects of the mutations while no disruptive molecular mechanism was detected.Collectively,our results highlight the important role of Fgfr1a gene in the adaptive evolution of schizothoracine fishes during their radiation in the Qinghai-Tibetan Plateau.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 30670287, 30471345 and 30200029)the Chinese Academy of Sciences (Grant No. KSCX2-SW-125)
文摘We recovered the phylogenetic relationships among 23 species and subspecies of the highly special-ized grade schizothoracine fishes distributing at 36 geographical sites in the Tibetan Plateau and its surrounding regions by analyzing sequences of cytochrome b genes. Furthermore, we estimated the possible divergent times among lineages based on a historical geological isolation event in the Tibetan Plateau. The molecular data revealed that the highly specialized grade schizothoracine fishes were not a monophyletic group, but were the same as genera Gymnocypris and Schizogypsis. Our results indi-cated that the molecular phylogenetic relationships apparently reflected their geographical and historical associations with drainages, namely species from the same and adjacent drainages clustered together and had close relationships. The divergence times of different lineages were well consistent with the rapid uplift phases of the Tibetan Plateau in the late Cenozoic, suggesting that the origin and evolution of schizothoracine fishes were strongly influenced by environment changes resulting from the upheaval of the Tibetan Plateau.
文摘Molecular phylogeny of three genera containing nine species and subspecies of the specialized schizothoracine fishes are investigated based on the complete nucleotide sequence of mitochondrial cytochrome b gene. Meantime relationships between the main cladogenetic events of the specialized schizothoracine fishes and the stepwise uplift of the Qinghai-Tibetan Plateau are also conducted using the molecular clock, which is calibrated by geological isolated events between the upper reaches of the Yellow River and the Qinghai Lake. Results indicated that the specialized schizothoracine fishes are not a monophyly. Five species and subspecies of Ptychobarbus form a monophyly. But three species of Gymnodiptychus do not form a monophyly. Gd.integrigymnatus is a sister taxon of the highly specialized schizothoracine fishes while Gdo pachycheilus has a close relation with Gd. dybowskii, and both of them are as a sister group of Diptychus maculatus. The specialized schizothoracines fishes might have originated during the Miocene(about 10 MaBP), and then the divergence of three genera happened during late Miocene (about 8 MaBP). Their main specialization occurred during the late Pliocene and Pleistocene (3.54-0.42 MaBP). The main cladogenetic events of the specialized schizothoracine fishes are mostly correlated with the geological tectonic events and intensive climate shift happened at 8, 3.6, 2.5 and 1.7 MaBP of the late Cenozoic.Molecular clock data do not support the hypothesis that the Qinghai-Tibetan Plateau uplifted to near present or even higher elevations during the Oligocene or Miocene, and neither in agreement with the view that the plateau uplifting reached only to an altitude of 2000 m during the late Pliocene(about 2.6 MaBP).
