The Experts below are selected from a list of 282 Experts worldwide ranked by ideXlab platform
Andreas Lücke - One of the best experts on this subject based on the ideXlab platform.
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A stable isotope record from freshwater lake shells of the eastern Tibetan Plateau, China, during the past two centuries
Boreas, 2007Co-Authors: Gerhard Hans Schleser, Andreas LückeAbstract:Lake Xingcuo is a small, closed, hardwater lake situated in the eastern Tibetan Plateau. Stable isotope data (delta O-18 and delta C-13) from the freshwater snail Gyraulus sibirica (Dunker) in a 34-cm-long, radioactive isotope-dated sediment core represent the past 200 years of Lake Xingcuo environmental history Carbon and oxygen isotope ratios in the shells of the snail yield information on the isotopic composition of the water in which the shell was formed, which in turn relates to climatic conditions prevailing during the snail's life-span. Living and fossil shells from Lake Xingcuo were collected. delta O-18 values in the living shells from Lake Xingcuo are in equilibrium with ambient waters, while delta C-13 values may trace snail dietary carbon. On comparing delta O-18 and delta C-13 in the shell of Gyraulus sibirica with monitored data for the period 1954-1995, we found that the delta O-18 composition in the shell is an efficient proxy revealing air temperature during the warmer months from April to September. There is a positive correlation between the delta O-18 in the shells of Gyraulus sibirica and the running average temperature of the warmer months. Climatic variability in the eastern Tibetan Plateau for the past two centuries has been inferred from the delta O-18 record from the freshwater snails in the sediments of Lake Xingcuo. As such, the last 200 years' palacoclimatic record for this region can be separated into three periods representing oscillations between warm and cool conditions consistent with the Guliya ice record in the Tibetan Plateau
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A stable isotope record from freshwater lake shells of the eastern Tibetan Plateau, China, during the past two centuries
Boreas, 2007Co-Authors: Gerhard Hans Schleser, Andreas LückeAbstract:Wu, J. L., Schleser, G. H., Lucke, A. & Li, S. 2007 (January): A stable isotope record from freshwater lake shells of the eastern Tibetan Plateau, China, during the past two centuries. Boreas, Vol. 36, pp. 38–46. Oslo. ISSN 0300–9483. Lake Xingcuo is a small, closed, hardwater lake situated in the eastern Tibetan Plateau. Stable isotope data (δ18O and δ13C) from the freshwater snail Gyraulus sibirica (Dunker) in a 34-cm-long, radioactive isotope-dated sediment core represent the past 200 years of Lake Xingcuo environmental history. Carbon and oxygen isotope ratios in the shells of the snail yield information on the isotopic composition of the water in which the shell was formed, which in turn relates to climatic conditions prevailing during the snail's life-span. Living and fossil shells from Lake Xingcuo were collected. δ18O values in the living shells from Lake Xingcuo are in equilibrium with ambient waters, while δ13C values may trace snail dietary carbon. On comparing δ18O and δ13C in the shell of Gyraulus sibirica with monitored data for the period 1954–1995, we found that the δ18O composition in the shell is an efficient proxy revealing air temperature during the warmer months from April to September. There is a positive correlation between the δ18O in the shells of Gyraulus sibirica and the running average temperature of the warmer months. Climatic variability in the eastern Tibetan Plateau for the past two centuries has been inferred from the δ18O record from the freshwater snails in the sediments of Lake Xingcuo. As such, the last 200 years' palaeoclimatic record for this region can be separated into three periods representing oscillations between warm and cool conditions consistent with the Guliya ice record in the Tibetan Plateau.
Frank Riedel - One of the best experts on this subject based on the ideXlab platform.
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how ancient is lake lugu yunnan china the gastropods viewpoint with focus on radix lymnaeidae
Journal of Great Lakes Research, 2020Co-Authors: Robert Wiese, Catharina Clewing, Frank Riedel, Christian Albrecht, Carolin Rabethge, Hucai ZhangAbstract:Abstract Lake Lugu has been termed an “ancient lake” in several publications. Ancient lakes, such as Baikal or Tanganyika have in common an age of several million years and an outstanding biodiversity and rate of endemism. Lake Lugu’s age is unknown, however, and has been inferred from the presumed Pliocene increased tectonic activity on the Yunnan-Guizhou Plateau. The lake was thus considered to be of tectonic origin, but supporting studies do not exist. Here we report and describe seven endemic species. The endemic gastropod Gyraulus luguhuensis exhibits an aberrant pseudo-dextral shell morphology, which is predominantly known from undisputed ancient lakes. To better understand the origin of the lake and of its biodiversity, we present a preliminary geological study, which shows that Lake Lugu is a tectonic-solution lake. During a survey of the aquatic habitats up to 21 gastropod morphospecies could be differentiated macro-morphologically. An aberrant neritid-like Radix was genetically studied for the first time. The genetic data suggest that Lugu-Radix, typical and neritid shell shapes, constitute a clade, comprising four possibly endemic evolutionary lineages, which potentially represent four different species. The molecular-clock approach indicates a Late Pliocene to Early Pleistocene origin of the clade, which we consider the minimum age of Lake Lugu. Our study reveals that the biodiversity in general and that of gastropods in particular is significantly higher than previously known. Against this background and considering the co-occurrence of aberrant Gyraulus and Radix with an evolutionary history of more than two million years, Lugu is putatively an ancient lake.
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How ancient is Lake Lugu (Yunnan, China)? The gastropods’ viewpoint with focus on Radix (Lymnaeidae)
Journal of Great Lakes Research, 2020Co-Authors: Robert Wiese, Catharina Clewing, Christian Albrecht, Carolin Rabethge, Hucai Zhang, Frank RiedelAbstract:Abstract Lake Lugu has been termed an “ancient lake” in several publications. Ancient lakes, such as Baikal or Tanganyika have in common an age of several million years and an outstanding biodiversity and rate of endemism. Lake Lugu’s age is unknown, however, and has been inferred from the presumed Pliocene increased tectonic activity on the Yunnan-Guizhou Plateau. The lake was thus considered to be of tectonic origin, but supporting studies do not exist. Here we report and describe seven endemic species. The endemic gastropod Gyraulus luguhuensis exhibits an aberrant pseudo-dextral shell morphology, which is predominantly known from undisputed ancient lakes. To better understand the origin of the lake and of its biodiversity, we present a preliminary geological study, which shows that Lake Lugu is a tectonic-solution lake. During a survey of the aquatic habitats up to 21 gastropod morphospecies could be differentiated macro-morphologically. An aberrant neritid-like Radix was genetically studied for the first time. The genetic data suggest that Lugu-Radix, typical and neritid shell shapes, constitute a clade, comprising four possibly endemic evolutionary lineages, which potentially represent four different species. The molecular-clock approach indicates a Late Pliocene to Early Pleistocene origin of the clade, which we consider the minimum age of Lake Lugu. Our study reveals that the biodiversity in general and that of gastropods in particular is significantly higher than previously known. Against this background and considering the co-occurrence of aberrant Gyraulus and Radix with an evolutionary history of more than two million years, Lugu is putatively an ancient lake.
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ecophenotypic plasticity leads to extraordinary gastropod shells found on the roof of the world
Ecology and Evolution, 2015Co-Authors: Catharina Clewing, Frank Riedel, Thomas Wilke, Christian AlbrechtAbstract:The often extraordinary shell forms and shapes of gastropods found in palaeolakes, such as the highly diverse Gyraulus fauna of the famous Steinheim Basin, have been puzzling evolutionary biologists for centuries, and there is an ongoing debate whether these aberrant shell forms are indicative of true species (or subspecies) or ecophenotypic morphs. Interestingly, one of the Steinheim Gyraulus morphs – a corkscrew-like open-coiled shell – has a recent analogue in the Lake Bangong drainage system on the western Tibetan Plateau. Therefore, a combination of morphological, molecular, palaeolimnological, and ecological analyses was used in this study to assess whether the extraordinary shell shape in Gyraulus sp. from this drainage system represents a (young) ecophenotypic phenomenon or if it has been genetically fixed over an extended period of time. Our morphological, ecological, and palaeolimnological data suggest that the corkscrew-like specimens remain restricted to a small pond near Lake Bangong with an elevated pH value and that the colonization may have occurred recently. The phylogenetic reconstruction based on two gene fragments shows that these nonplanispiral specimens cluster within the previous described Tibetan Plateau Gyraulus clade N2. A network analysis indicates that some haplotypes are even shared by planispiral and nonplanispiral specimens. Given the ephemerality of the phenomenon, the compact network patterns inferred, the likely young phylogenetic age of the aberrant Gyraulus shells studied, and the ecological peculiarities of the study site, we suggest that the evolution of the aberrant shell forms on the Tibetan Plateau could likely be considered as a rapid ecophenotypic response, possibly induced by ecological stress. This finding may thus have implications for the ongoing debate about the processes that have caused the extraordinary shell diversity in palaeolakes such as the Steinheim Basin.
Gerhard Hans Schleser - One of the best experts on this subject based on the ideXlab platform.
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A stable isotope record from freshwater lake shells of the eastern Tibetan Plateau, China, during the past two centuries
Boreas, 2007Co-Authors: Gerhard Hans Schleser, Andreas LückeAbstract:Lake Xingcuo is a small, closed, hardwater lake situated in the eastern Tibetan Plateau. Stable isotope data (delta O-18 and delta C-13) from the freshwater snail Gyraulus sibirica (Dunker) in a 34-cm-long, radioactive isotope-dated sediment core represent the past 200 years of Lake Xingcuo environmental history Carbon and oxygen isotope ratios in the shells of the snail yield information on the isotopic composition of the water in which the shell was formed, which in turn relates to climatic conditions prevailing during the snail's life-span. Living and fossil shells from Lake Xingcuo were collected. delta O-18 values in the living shells from Lake Xingcuo are in equilibrium with ambient waters, while delta C-13 values may trace snail dietary carbon. On comparing delta O-18 and delta C-13 in the shell of Gyraulus sibirica with monitored data for the period 1954-1995, we found that the delta O-18 composition in the shell is an efficient proxy revealing air temperature during the warmer months from April to September. There is a positive correlation between the delta O-18 in the shells of Gyraulus sibirica and the running average temperature of the warmer months. Climatic variability in the eastern Tibetan Plateau for the past two centuries has been inferred from the delta O-18 record from the freshwater snails in the sediments of Lake Xingcuo. As such, the last 200 years' palacoclimatic record for this region can be separated into three periods representing oscillations between warm and cool conditions consistent with the Guliya ice record in the Tibetan Plateau
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A stable isotope record from freshwater lake shells of the eastern Tibetan Plateau, China, during the past two centuries
Boreas, 2007Co-Authors: Gerhard Hans Schleser, Andreas LückeAbstract:Wu, J. L., Schleser, G. H., Lucke, A. & Li, S. 2007 (January): A stable isotope record from freshwater lake shells of the eastern Tibetan Plateau, China, during the past two centuries. Boreas, Vol. 36, pp. 38–46. Oslo. ISSN 0300–9483. Lake Xingcuo is a small, closed, hardwater lake situated in the eastern Tibetan Plateau. Stable isotope data (δ18O and δ13C) from the freshwater snail Gyraulus sibirica (Dunker) in a 34-cm-long, radioactive isotope-dated sediment core represent the past 200 years of Lake Xingcuo environmental history. Carbon and oxygen isotope ratios in the shells of the snail yield information on the isotopic composition of the water in which the shell was formed, which in turn relates to climatic conditions prevailing during the snail's life-span. Living and fossil shells from Lake Xingcuo were collected. δ18O values in the living shells from Lake Xingcuo are in equilibrium with ambient waters, while δ13C values may trace snail dietary carbon. On comparing δ18O and δ13C in the shell of Gyraulus sibirica with monitored data for the period 1954–1995, we found that the δ18O composition in the shell is an efficient proxy revealing air temperature during the warmer months from April to September. There is a positive correlation between the δ18O in the shells of Gyraulus sibirica and the running average temperature of the warmer months. Climatic variability in the eastern Tibetan Plateau for the past two centuries has been inferred from the δ18O record from the freshwater snails in the sediments of Lake Xingcuo. As such, the last 200 years' palaeoclimatic record for this region can be separated into three periods representing oscillations between warm and cool conditions consistent with the Guliya ice record in the Tibetan Plateau.
C T Wolmarans - One of the best experts on this subject based on the ideXlab platform.
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Verspreiding en habitats van Gyraulus costulatus , potensiële slaktussengasheer van ingewandsbotte van die familie Echinostomatidae in Suid-Afrika : research and review article
2004Co-Authors: K N De Kock, C T WolmaransAbstract:Hierdie artikel fokus op die geografiese verspreiding en habitats van Gyraulus costulatusl/Ig soos weerspieel deur die 736 vindplekke wat tans in die databasis van die Nasionale Varswaterslakversameling (NVWSV) van Suid-Afrika op rekord is. Alhoewel 'n wye verskeidenheid tipes waterliggame vir hierdie spesie gerapporteer is, was die grootste getal monsters afkomstig uit riviere, spruite en damme waarvan die water oorwegend as standhoudend, vars en helderkleurig aangeteken is. 'n Hoofsaaklik klipperige substraat en die teenwoordigheid van waterplante is vir die meerderheid vindplekke tydens opnames gerapporteer. 'n Geintegreerde besluitnemingsboom wat uit die data saamgestel is, het aangetoon dat hoogte bo seevlak, temperatuur en waterliggame die belangrikste van die ondersoekte faktore is wat die gedokumenteerde geografiese verspreiding van hierdie spesie in Suid-Afrika bepaal het en dit word ondersteun deur die effekgroottewaardes wat vir elke veranderlike afsonderlik bereken is. Die lae prioriteit wat veldopnames om die geografiese verspreiding van varswaterslakke en slakgedraagde parasitiese siektes te moniteer en op te dateer sedert die vroee tagtigerjare van die vorige eeu en tans nog geniet, is kommerwekkend. Dit word aanbeveel dat die presiese rol van G. costulatusl/Ig in die epidemiologie van ekonomies belangrike wurmparasiete in Suid-Afrika ondersoek word. End Distribution and habitats of Gyraulus costulatus , potential snail intermediate host of intestinal flukes of the family Echinostomatidae in South Africa This paper focuses on the geographical distribution and habitats of Gyraulus costulatus , as reflected by the 736 localities currently on record in the database of the National Freshwater Snail Collection (NFSC) of South Africa. Although a wide variety of water body types was reported for this species, the largest number of samples were yielded by rivers, streams and dams which were described as perennial with predominantly fresh and clear water. A mainly stony substrate and the presence of aquatic vegetation were recorded for the majority of localities at the time of survey. An integrated decision tree constructed from the data indicated that altitude, temperature and water bodies were the most important of the factors investigated that determined the documented geographical distribution of this species in South Africa. This was supported by the effect size values calculated separately for each factor. Since the early eighties of the previous century, surveys to monitor and update the geographical distribution of freshwater snails and snail-borne parasitic diseases have been relegated to a low priority issue and this is a matter of concern. It is recommended that the exact role of G. costulatusl/Ig in the epidemiology of economically important helminth parasites in South Africa should be investigated. End
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verspreiding en habitats van Gyraulus connollyi slaktussengasheer van ingewandsbotte van die familie echinostomatidae in suid afrika
2004Co-Authors: K N De Kock, C T WolmaransAbstract:Distribution and habitats of Gyraulus connollyi, snail intermediate host of intestinal flukes of the family Echinostomatidae, in South Africa This paper focuses on the geographical distribution and habitats of Gyraulus connollyi, snail intermediate host of intestinal flukes of the family Echinostomatidae as reflected by the 969 collection sites on record in the database of the National Freshwater Snail Collection (NFSC) of South Africa. The presence of this species was reported from 13 different types of water-bodies, however, the highest percentage by far was collected in streams and rivers and in habitats of which the water was described as perennial, clear and fresh. A predominantly stony substratum and the presence of vegetation were also reported for the majority of habitats. The effect size was calculated for each variable to determine its importance for the occurrence of this species. An integrated decision tree constructed from the data indicated that temperature, altitude and type of water-body were the most important of the factors evaluated that could have an effect on the geographical distribution of this species. This was supported by the effect size values calculated for each variable. A temperature index calculated for each species in the database ranked G. connollyi seventh out of 53 due to its association with low temperatures. Although human echinostomosis has not yet been diagnosed in Africa, concern is expressed that G. connollyi is able to serve as first intermediate host in the transmission of echinostomosis.
Christian Albrecht - One of the best experts on this subject based on the ideXlab platform.
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how ancient is lake lugu yunnan china the gastropods viewpoint with focus on radix lymnaeidae
Journal of Great Lakes Research, 2020Co-Authors: Robert Wiese, Catharina Clewing, Frank Riedel, Christian Albrecht, Carolin Rabethge, Hucai ZhangAbstract:Abstract Lake Lugu has been termed an “ancient lake” in several publications. Ancient lakes, such as Baikal or Tanganyika have in common an age of several million years and an outstanding biodiversity and rate of endemism. Lake Lugu’s age is unknown, however, and has been inferred from the presumed Pliocene increased tectonic activity on the Yunnan-Guizhou Plateau. The lake was thus considered to be of tectonic origin, but supporting studies do not exist. Here we report and describe seven endemic species. The endemic gastropod Gyraulus luguhuensis exhibits an aberrant pseudo-dextral shell morphology, which is predominantly known from undisputed ancient lakes. To better understand the origin of the lake and of its biodiversity, we present a preliminary geological study, which shows that Lake Lugu is a tectonic-solution lake. During a survey of the aquatic habitats up to 21 gastropod morphospecies could be differentiated macro-morphologically. An aberrant neritid-like Radix was genetically studied for the first time. The genetic data suggest that Lugu-Radix, typical and neritid shell shapes, constitute a clade, comprising four possibly endemic evolutionary lineages, which potentially represent four different species. The molecular-clock approach indicates a Late Pliocene to Early Pleistocene origin of the clade, which we consider the minimum age of Lake Lugu. Our study reveals that the biodiversity in general and that of gastropods in particular is significantly higher than previously known. Against this background and considering the co-occurrence of aberrant Gyraulus and Radix with an evolutionary history of more than two million years, Lugu is putatively an ancient lake.
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How ancient is Lake Lugu (Yunnan, China)? The gastropods’ viewpoint with focus on Radix (Lymnaeidae)
Journal of Great Lakes Research, 2020Co-Authors: Robert Wiese, Catharina Clewing, Christian Albrecht, Carolin Rabethge, Hucai Zhang, Frank RiedelAbstract:Abstract Lake Lugu has been termed an “ancient lake” in several publications. Ancient lakes, such as Baikal or Tanganyika have in common an age of several million years and an outstanding biodiversity and rate of endemism. Lake Lugu’s age is unknown, however, and has been inferred from the presumed Pliocene increased tectonic activity on the Yunnan-Guizhou Plateau. The lake was thus considered to be of tectonic origin, but supporting studies do not exist. Here we report and describe seven endemic species. The endemic gastropod Gyraulus luguhuensis exhibits an aberrant pseudo-dextral shell morphology, which is predominantly known from undisputed ancient lakes. To better understand the origin of the lake and of its biodiversity, we present a preliminary geological study, which shows that Lake Lugu is a tectonic-solution lake. During a survey of the aquatic habitats up to 21 gastropod morphospecies could be differentiated macro-morphologically. An aberrant neritid-like Radix was genetically studied for the first time. The genetic data suggest that Lugu-Radix, typical and neritid shell shapes, constitute a clade, comprising four possibly endemic evolutionary lineages, which potentially represent four different species. The molecular-clock approach indicates a Late Pliocene to Early Pleistocene origin of the clade, which we consider the minimum age of Lake Lugu. Our study reveals that the biodiversity in general and that of gastropods in particular is significantly higher than previously known. Against this background and considering the co-occurrence of aberrant Gyraulus and Radix with an evolutionary history of more than two million years, Lugu is putatively an ancient lake.
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ecophenotypic plasticity leads to extraordinary gastropod shells found on the roof of the world
Ecology and Evolution, 2015Co-Authors: Catharina Clewing, Frank Riedel, Thomas Wilke, Christian AlbrechtAbstract:The often extraordinary shell forms and shapes of gastropods found in palaeolakes, such as the highly diverse Gyraulus fauna of the famous Steinheim Basin, have been puzzling evolutionary biologists for centuries, and there is an ongoing debate whether these aberrant shell forms are indicative of true species (or subspecies) or ecophenotypic morphs. Interestingly, one of the Steinheim Gyraulus morphs – a corkscrew-like open-coiled shell – has a recent analogue in the Lake Bangong drainage system on the western Tibetan Plateau. Therefore, a combination of morphological, molecular, palaeolimnological, and ecological analyses was used in this study to assess whether the extraordinary shell shape in Gyraulus sp. from this drainage system represents a (young) ecophenotypic phenomenon or if it has been genetically fixed over an extended period of time. Our morphological, ecological, and palaeolimnological data suggest that the corkscrew-like specimens remain restricted to a small pond near Lake Bangong with an elevated pH value and that the colonization may have occurred recently. The phylogenetic reconstruction based on two gene fragments shows that these nonplanispiral specimens cluster within the previous described Tibetan Plateau Gyraulus clade N2. A network analysis indicates that some haplotypes are even shared by planispiral and nonplanispiral specimens. Given the ephemerality of the phenomenon, the compact network patterns inferred, the likely young phylogenetic age of the aberrant Gyraulus shells studied, and the ecological peculiarities of the study site, we suggest that the evolution of the aberrant shell forms on the Tibetan Plateau could likely be considered as a rapid ecophenotypic response, possibly induced by ecological stress. This finding may thus have implications for the ongoing debate about the processes that have caused the extraordinary shell diversity in palaeolakes such as the Steinheim Basin.