The Experts below are selected from a list of 3063 Experts worldwide ranked by ideXlab platform
Bert Van Bocxlaer - One of the best experts on this subject based on the ideXlab platform.
-
palaeobiology and evolution of the late cenozoic Freshwater Molluscs of the turkana basin unionidae rafinesque 1820 partim coelatura bivalvia unionoidea
Journal of Systematic Palaeontology, 2011Co-Authors: Bert Van BocxlaerAbstract:The Plio-Pleistocene Freshwater Molluscs of the Omo-Turkana Basin were long considered to be a prima facie example of punctuated equilibrium evolution. However, the absence of a study on their taxonomy has significantly hampered the debate on assumed evolutionary patterns. This paper addresses the systematics and palaeobiology of the bivalve genus Coelatura Conrad, 1853 in the basin. It reveals that a Coelatura species was assigned to the extinct genus Pseudobovaria Adam, 1957 in earlier studies, while another species formerly assigned to Coelatura is not discussed here because it belongs to the extinct Pseudodiplon Adam, 1957. Six Coelatura species are recognized in the Plio-Pleistocene Omo-Turkana Basin, two of which are new to science: C. rhomboidalis sp. nov. and C. magna sp. nov. These two species are considered lacustrine adapted species, both with a strongly dorsally protruded umbo. This adaptation apparently evolved twice independently in the basin within a ∼1 Ma period, but it is not observed in ...
-
palaeobiology and evolution of the late cenozoic Freshwater Molluscs of the turkana basin iridinidae swainson 1840 and etheriidae deshayes 1830 bivalvia etherioidea
Journal of Systematic Palaeontology, 2009Co-Authors: Bert Van Bocxlaer, Dirk Van DammeAbstract:The palaeobiology of the Late Cenozoic Freshwater Molluscs that inhabited the Omo-Turkana Basin, situated in the eastern branch of the East African Rift System (Ethiopia, Kenya), remains poorly documented. Here we revise the taxonomy and palaeobiology of the bivalve superfamily Etherioidea from this region and discuss some palaeohydrological implications. In the Iridininae (Mutela, Pleiodon), the genus Iridina Lamarck, 1819 is revived for elongated iridinids with a denticulated hinge, since all fossil Iridininae of the Omo-Turkana Basin and most Miocene-Early Pleistocene Iridininae elsewhere in Africa have denticulate hinges that are not comparable to those of modern Mutela. In addition to the ubiquitous Etheria elliptica (Etheriidae), 11 iridinids are described, five of which are new to science, namely Chambardia feibeli, Iridina turkanica, I. omoensis, I. browni and Pleiodon bentoni. Most species do not show lacustrine adaptations and are/were part of a widespread East African fauna. This confirms the highly unstable character of the Pliocene-Holocene aquatic ecosystems in the Omo-Turkana Basin. Indications for intralacustrine speciation are only observed in the Late Pliocene-Early Pleistocene long-lived (similar to 250 ka or longer) Palaeolake Lorenyang. Williamson's (1981) evolutionary model for the Omo-Turkana Basin Molluscs does not apply to the Etherioidea.
-
Freshwater Molluscs of the nile basin past and present
The Nile: Origin environments limnology and human use, 2009Co-Authors: Dirk Van Damme, Bert Van BocxlaerAbstract:The malacofauna of the Nile is poor compared to that of the Congo and its degree of endemicity is lower. While the highest species richness of the Congo Basin is in stenotopic taxa that live in the rivers and lakes, the highest diversity in the Nile Basin occurs in eurytopic taxa living in fringe habitats such as temporary pools. The paucity of endemics that need perennial waters as well in the Lower Nile as in the White Nile confirms the geological evidence indicating instability and discontinuity in water supply during Plio-Pleistocene times. The fauna of the Nile is predominantly Afrotropical in the Lower Nile and exclusively Afrotropical south of the junction of the White Nile and Blue Nile. Of all sub-basins, the degree of endemicity (either zero or two species) is lowest in the Equatorial Nile, indicating that the perennial aquatic environment in this sub-basin is young (probably Holocene) and lending support to the idea that the Bahr el Arab and White Nile Transcontinental Rift System were hydrologically unstable, with endorheic, alkaline lakes during most of the Plio-Pleistocene (Salama, 1997). In the Lower (Egyptian) Nile and in the Ethiopian Highlands palaearctic faunal components occur, consisting of widespread species and of a limited number of endemics of palaearctic origin, related to Levantine species. Most of these taxa first appear in the fossil record around 2.5 Ma. There is no evidence that the Nile functioned as an invasion route for Eurasiatic species prior to that time. Only Theodoxus niloticus is possibly of Paratethyan origin and may have invaded in the Late Miocene. The main invasion of Freshwater Molluscs into Africa appears to have occurred via the Horn of Africa in Middle and Late Miocene times. In the East African Rift, a diversified fauna occurs that only shares a fraction of species with the Nile Basin north of the Albert Nile (> ∼5° N). In the equato- rial headwaters, some species from southern Africa reach their northern limit, but the main community consists of species that are either endemic to one of the rift lakes or endemic to the region stretching from Turkana to the Kivu Basins. There hence exists a distinct East African bio-province, that was already recognisable in
Juan Carlos Pérez-quintero - One of the best experts on this subject based on the ideXlab platform.
-
Environmental determinants of Freshwater mollusc biodiversity and identification of priority areas for conservation in Mediterranean water courses
Biodiversity and Conservation, 2012Co-Authors: Juan Carlos Pérez-quinteroAbstract:This study evaluates which environmental factors influence the biodiversity, distribution and conservation of Freshwater mollusc communities in a Mediterranean Biosphere Reserve in the south-western Iberian Peninsula. Habitat features and two biodiversity indices (native species richness and diversity) were evaluated at 109 locations. Environmental gradients were assessed using principal component analysis, which orders the habitat variables along two gradients: headwater characteristics and water availability. According to a canonical correspondence analysis, the main environmental factors related to the distribution of species and community structure were, also, climate and headwater habitat features (precipitation, order, channel width, slope and pH), and heterogeneity and trophic features (IHF index and instream macrophytes cover). Relationships between biodiversity indices and environmental variables were best explained by a regression model incorporating, basically, aridity index and precipitation as the variables that accounted for most of the variance. This study demonstrates that distribution of Freshwater Molluscs along a highly stressed by drought Mediterranean region mostly depends on the local pool of species and their adaptive patterns to water availability.
-
Distribution patterns of Freshwater Molluscs along environmental gradients in the southern Guadiana River basin (SW Iberian Peninsula)
Hydrobiologia, 2011Co-Authors: Juan Carlos Pérez-quinteroAbstract:The taxonomic status of the Freshwater mollusc fauna of the Iberian Peninsula it is reasonably well known, but, unlike other benthic macroinvertebrate, its distribution and ecology has been poorly studied. In this article, I study the relationships between environmental characteristics and distribution and community structure of Freshwater Molluscs along climatic, hydrological, physicochemical, and heterogeneity gradients in the southwestern Iberian Peninsula. Ninety-four sampling points were analysed, in which, in addition to habitat features, the presence/absence and abundance of species were evaluated. The environmental gradients were measured by use of principal-components analysis (PAC), which orders the variables along two gradients: headwaters-mouth gradient (PC1) and water availability (PC2). According to canonical correspondence analysis (CCA), the main environmental factors related to species distribution and community structure were conductivity, permanency, channel width, turbidity, slope, and distance to the main river axis. The relationship between biodiversity (measured as species richness and the Shannon–Weiner diversity index), the ratio of the number of introduced species to the total number of species (zoogeographic integrity coefficient), and environmental variables was best explained by a regression model incorporating, basically, the permanence of water in streams as the variable that accounted for most of the variance. This study demonstrates that the distribution of Freshwater Molluscs along a Mediterranean gradient highly stressed by drought depends, mainly, on the hydrological stability and environmental conditions of the headwaters and estuarine sites.
Darren C. J. Yeo - One of the best experts on this subject based on the ideXlab platform.
-
Molluscs for sale assessment of Freshwater gastropods and bivalves in the ornamental pet trade
PLOS ONE, 2016Co-Authors: Siong Kiat Tan, Wing Hing Wong, Rudolf Meier, Sow-yan Chan, Heok Hui Tan, Darren C. J. YeoAbstract:The ornamental pet trade is often considered a key culprit for conservation problems such as the introduction of invasive species (including infectious diseases) and overharvesting of rare species. Here, we present the first assessment of the biodiversity of Freshwater Molluscs in the ornamental pet trade in Singapore, one of the most important global hubs of the ornamental aquarium trade, and discuss associated conservation concerns. We recorded Freshwater Molluscs from ornamental pet shops and major exporters including non-ornamental species (e.g., hitchhikers, Molluscs sold as fish feed). We recorded an unexpectedly high diversity—59 species—of Freshwater bivalves and gastropods, with the majority (38 species or 64%) being from the Oriental region. In addition to morphological examination, we sequenced the DNA barcode region of mitochondrial CO1 and 16S genes to provide molecular data for the confirmation of the identification and for future re-identification. DNA barcodes were obtained for 50 species, and all but four were separated by > 3% uncorrected pairwise distances. The trade has been considered a main introduction pathway for non-native species to Singapore, and we found that out of 15 species in the trade as well as in the wild in Singapore, 12 are either introduced or of unknown origin, representing almost half of the known non-native Freshwater Molluscs in Singapore. Particularly prevalent are non-ornamental species: six hitchhikers on aquarium plants and six species sold as fish feed. We found that a quarter of the trade species have a history of introduction, which includes 11 known or potentially invasive species. We conclude that potential overharvesting is difficult to assess because only half of the trade species have been treated by IUCN. Of these, 21 species are of Least Concern and three are Data Deficient. Our checklist, with accompanying DNA barcodes, images, and museum vouchers, provides an important reference library for future monitoring, and constitutes a step toward creating a more sustainable ornamental pet trade.
-
Freshwater Molluscs in the ornamental pet trade.
2016Co-Authors: Siong Kiat Tan, Wing Hing Wong, Rudolf Meier, Sow-yan Chan, Heok Hui Tan, Darren C. J. YeoAbstract:Unless indicated differently, scale bars = 10mm. 1. Batissa similis; 2. Batissa violacea; 3. Corbicula fluminea; 4. Corbicula moltkiana; 5. Hyriopsis bialata; 6. Hyriopsis desowitzi; 7. Parreysia burmana; 8. Parreysia tavoyensis; 9. Pilsbryoconcha exilis; 10. Scabies crispata; 11. Sinanodonta woodiana; 12. Unionetta fabagina; 13. Marisa cornuarietis; 14. Pomacea canaliculata; 15. Pomacea diffusa; 16. Pomacea maculata (photograph by K.A. Hayes); 17. Bithynia sp.; 18. Clea bockii; 19. Clea helena; 20. Radix rubiginosa; 21. Clithon corona; 22. Clithon diadema; 23. Clithon lentiginosum; 24. Clithon mertoniana; 25. Neripteron auriculata; 26. Neritina iris; 27. Neritina juttingae; 28. Neritina violacea; 29. Neritodryas cornea; 30. Septaria porcellana; 31. Vittina coromandeliana; 32. Vittina turrita; 33. Vittina waigiensis; 34. Brotia armata; 35. Brotia binodosa; 36. Brotia herculea; 37. Brotia pagodula; 38. Sulcospira tonkiniana; 39. Tylomelania towutica; 40. Tylomelania sp.; 41. Tylomelania sp.; 42. Tylomelania sp.; 43. Physa sp.; 44. Amerianna carinata; 45. Indoplanorbis exustus; 46. Gyraulus convexiusculus; 47. Semisulcospira sp.; 48. Melanoides tuberculata; 49. Stenomelania offachiensis; 50. Stenomelania plicaria; 51. Stenomelania cf. plicaria; 52. Stenomelania sp.; 53. Thiara cancellata; 54. Celetaia persculpta; 55. Filopaludina cambodjensis; 56. Filopaludina peninsularis; 57. Filopaludina polygramma; 58. Sinotaia guangdungensis; 59. Taia pseudoshanensis.
Rudolf Meier - One of the best experts on this subject based on the ideXlab platform.
-
Molluscs for sale assessment of Freshwater gastropods and bivalves in the ornamental pet trade
PLOS ONE, 2016Co-Authors: Siong Kiat Tan, Wing Hing Wong, Rudolf Meier, Sow-yan Chan, Heok Hui Tan, Darren C. J. YeoAbstract:The ornamental pet trade is often considered a key culprit for conservation problems such as the introduction of invasive species (including infectious diseases) and overharvesting of rare species. Here, we present the first assessment of the biodiversity of Freshwater Molluscs in the ornamental pet trade in Singapore, one of the most important global hubs of the ornamental aquarium trade, and discuss associated conservation concerns. We recorded Freshwater Molluscs from ornamental pet shops and major exporters including non-ornamental species (e.g., hitchhikers, Molluscs sold as fish feed). We recorded an unexpectedly high diversity—59 species—of Freshwater bivalves and gastropods, with the majority (38 species or 64%) being from the Oriental region. In addition to morphological examination, we sequenced the DNA barcode region of mitochondrial CO1 and 16S genes to provide molecular data for the confirmation of the identification and for future re-identification. DNA barcodes were obtained for 50 species, and all but four were separated by > 3% uncorrected pairwise distances. The trade has been considered a main introduction pathway for non-native species to Singapore, and we found that out of 15 species in the trade as well as in the wild in Singapore, 12 are either introduced or of unknown origin, representing almost half of the known non-native Freshwater Molluscs in Singapore. Particularly prevalent are non-ornamental species: six hitchhikers on aquarium plants and six species sold as fish feed. We found that a quarter of the trade species have a history of introduction, which includes 11 known or potentially invasive species. We conclude that potential overharvesting is difficult to assess because only half of the trade species have been treated by IUCN. Of these, 21 species are of Least Concern and three are Data Deficient. Our checklist, with accompanying DNA barcodes, images, and museum vouchers, provides an important reference library for future monitoring, and constitutes a step toward creating a more sustainable ornamental pet trade.
-
Freshwater Molluscs in the ornamental pet trade.
2016Co-Authors: Siong Kiat Tan, Wing Hing Wong, Rudolf Meier, Sow-yan Chan, Heok Hui Tan, Darren C. J. YeoAbstract:Unless indicated differently, scale bars = 10mm. 1. Batissa similis; 2. Batissa violacea; 3. Corbicula fluminea; 4. Corbicula moltkiana; 5. Hyriopsis bialata; 6. Hyriopsis desowitzi; 7. Parreysia burmana; 8. Parreysia tavoyensis; 9. Pilsbryoconcha exilis; 10. Scabies crispata; 11. Sinanodonta woodiana; 12. Unionetta fabagina; 13. Marisa cornuarietis; 14. Pomacea canaliculata; 15. Pomacea diffusa; 16. Pomacea maculata (photograph by K.A. Hayes); 17. Bithynia sp.; 18. Clea bockii; 19. Clea helena; 20. Radix rubiginosa; 21. Clithon corona; 22. Clithon diadema; 23. Clithon lentiginosum; 24. Clithon mertoniana; 25. Neripteron auriculata; 26. Neritina iris; 27. Neritina juttingae; 28. Neritina violacea; 29. Neritodryas cornea; 30. Septaria porcellana; 31. Vittina coromandeliana; 32. Vittina turrita; 33. Vittina waigiensis; 34. Brotia armata; 35. Brotia binodosa; 36. Brotia herculea; 37. Brotia pagodula; 38. Sulcospira tonkiniana; 39. Tylomelania towutica; 40. Tylomelania sp.; 41. Tylomelania sp.; 42. Tylomelania sp.; 43. Physa sp.; 44. Amerianna carinata; 45. Indoplanorbis exustus; 46. Gyraulus convexiusculus; 47. Semisulcospira sp.; 48. Melanoides tuberculata; 49. Stenomelania offachiensis; 50. Stenomelania plicaria; 51. Stenomelania cf. plicaria; 52. Stenomelania sp.; 53. Thiara cancellata; 54. Celetaia persculpta; 55. Filopaludina cambodjensis; 56. Filopaludina peninsularis; 57. Filopaludina polygramma; 58. Sinotaia guangdungensis; 59. Taia pseudoshanensis.
-
importance of reservoirs for the conservation of Freshwater Molluscs in a tropical urban landscape
Biological Conservation, 2006Co-Authors: Reuben Clements, Lian Pin Koh, Tien Ming Lee, Rudolf MeierAbstract:Abstract Freshwater species and ecosystems are gravely imperiled, particularly within urban landscapes of tropical Asia. In one of the region’s most urbanized landscapes (i.e., Singapore), we determined: (1) the importance of six different habitats (i.e., catchment reservoirs, estuarine reservoirs, forest streams, rural streams, ponds and monsoon canals) for conserving the diversity of Freshwater Molluscs; (2) key environmental factors (e.g., pH) affecting molluscan distribution; (3) important biogeographical determinants (e.g., area) of molluscan richness within each habitat; and (4) the habitat affinities of introduced species. High sampling saturation was achieved at most study habitats with minimal sampling effort, suggesting that the utilization of Molluscs as bioindicators can expedite Freshwater conservation initiatives. Estuarine reservoirs (6.0 ± 2.0) had the highest molluscan richness, vis-a-vis catchment reservoirs, forest streams, rural streams, ponds and monsoon canals (3.0 ± 1.5; 0; 3.3 ± 2.0; 1.8 ± 0.5 and 3.5 ± 0.5 respectively). Both reservoir types possessed species compositions distinct from other habitats and contained majority (76%) of the sampled species. Reservoirs therefore serve to conserve the bulk of local Freshwater malacofauna, especially if they are maintained at near-neutral pH levels (i.e., ∼7.3) and contain large substrates (i.e., rocks). Area was the best predictor of molluscan richness across all habitats, implying that larger Freshwater habitats require higher conservation priorities than smaller ones. Introduced (non-native) species (e.g., Pomacea canaliculata ) had high affinities for reservoirs, which are in need of monitoring to curb population expansions. The interminable growth of human settlements urgently requires a reconciliatory approach, which includes the ecologically-sound design and management of modified habitats to complement reserves in sustaining native Freshwater species.
Dirk Van Damme - One of the best experts on this subject based on the ideXlab platform.
-
palaeobiology and evolution of the late cenozoic Freshwater Molluscs of the turkana basin iridinidae swainson 1840 and etheriidae deshayes 1830 bivalvia etherioidea
Journal of Systematic Palaeontology, 2009Co-Authors: Bert Van Bocxlaer, Dirk Van DammeAbstract:The palaeobiology of the Late Cenozoic Freshwater Molluscs that inhabited the Omo-Turkana Basin, situated in the eastern branch of the East African Rift System (Ethiopia, Kenya), remains poorly documented. Here we revise the taxonomy and palaeobiology of the bivalve superfamily Etherioidea from this region and discuss some palaeohydrological implications. In the Iridininae (Mutela, Pleiodon), the genus Iridina Lamarck, 1819 is revived for elongated iridinids with a denticulated hinge, since all fossil Iridininae of the Omo-Turkana Basin and most Miocene-Early Pleistocene Iridininae elsewhere in Africa have denticulate hinges that are not comparable to those of modern Mutela. In addition to the ubiquitous Etheria elliptica (Etheriidae), 11 iridinids are described, five of which are new to science, namely Chambardia feibeli, Iridina turkanica, I. omoensis, I. browni and Pleiodon bentoni. Most species do not show lacustrine adaptations and are/were part of a widespread East African fauna. This confirms the highly unstable character of the Pliocene-Holocene aquatic ecosystems in the Omo-Turkana Basin. Indications for intralacustrine speciation are only observed in the Late Pliocene-Early Pleistocene long-lived (similar to 250 ka or longer) Palaeolake Lorenyang. Williamson's (1981) evolutionary model for the Omo-Turkana Basin Molluscs does not apply to the Etherioidea.
-
Freshwater Molluscs of the nile basin past and present
The Nile: Origin environments limnology and human use, 2009Co-Authors: Dirk Van Damme, Bert Van BocxlaerAbstract:The malacofauna of the Nile is poor compared to that of the Congo and its degree of endemicity is lower. While the highest species richness of the Congo Basin is in stenotopic taxa that live in the rivers and lakes, the highest diversity in the Nile Basin occurs in eurytopic taxa living in fringe habitats such as temporary pools. The paucity of endemics that need perennial waters as well in the Lower Nile as in the White Nile confirms the geological evidence indicating instability and discontinuity in water supply during Plio-Pleistocene times. The fauna of the Nile is predominantly Afrotropical in the Lower Nile and exclusively Afrotropical south of the junction of the White Nile and Blue Nile. Of all sub-basins, the degree of endemicity (either zero or two species) is lowest in the Equatorial Nile, indicating that the perennial aquatic environment in this sub-basin is young (probably Holocene) and lending support to the idea that the Bahr el Arab and White Nile Transcontinental Rift System were hydrologically unstable, with endorheic, alkaline lakes during most of the Plio-Pleistocene (Salama, 1997). In the Lower (Egyptian) Nile and in the Ethiopian Highlands palaearctic faunal components occur, consisting of widespread species and of a limited number of endemics of palaearctic origin, related to Levantine species. Most of these taxa first appear in the fossil record around 2.5 Ma. There is no evidence that the Nile functioned as an invasion route for Eurasiatic species prior to that time. Only Theodoxus niloticus is possibly of Paratethyan origin and may have invaded in the Late Miocene. The main invasion of Freshwater Molluscs into Africa appears to have occurred via the Horn of Africa in Middle and Late Miocene times. In the East African Rift, a diversified fauna occurs that only shares a fraction of species with the Nile Basin north of the Albert Nile (> ∼5° N). In the equato- rial headwaters, some species from southern Africa reach their northern limit, but the main community consists of species that are either endemic to one of the rift lakes or endemic to the region stretching from Turkana to the Kivu Basins. There hence exists a distinct East African bio-province, that was already recognisable in
