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
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...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).
文摘裂腹鱼亚科鱼类长期生活在青藏高原缺氧环境,是研究低氧适应机制的天然生物模型。对3种裂腹鱼:高海拔(>3600 m)的孤唇裂腹鱼和巨须裂腹鱼与低海拔(<700 m)齐口裂腹鱼的主要渗透调节器官肾脏进行转录组分析。通过对孤唇裂腹鱼和巨须裂腹鱼与齐口裂腹鱼的肾脏转录组进行比较分析,分别筛选出504个和478个差异表达基因,其中有199个共同差异表达基因。对共同差异基因进行GO(Gene Ontology)和KEGG(Kyoto Encyclopedia of Genes and Genomes)的富集分析发现,两组共同差异基因主要富集在糖酵解/糖原生成过程、脂质生物合成过程和血管生成等通路上。其中eno3、fbp1α、prpf19和ctsz等基因的高表达可能在高海拔裂腹鱼长期适应低氧环境中起着重要作用。本研究为揭示高原鱼类长期低氧适应提供了新思路。
