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H W Raadsma - One of the best experts on this subject based on the ideXlab platform.
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genome wide genetic diversity of holstein friesian cattle reveals new insights into australian and Global Population variability including impact of selection
Animal Genetics, 2007Co-Authors: Kyall R Zenger, Mehar S Khatkar, J A L Cavanagh, Rachel Hawken, H W RaadsmaAbstract:Past breeding strategies for dairy cattle have been very effective in producing rapid genetic gain to achieve industry targets and raise profitability. Such gains have been largely facilitated by intense selection of sires combined with the use of artificial insemination. However, this practice can potentially limit the level of genetic diversity through inbreeding and selection plateaus. The rate of inbreeding in Australia is increasing, primarily as a result of semen importation from a small number of prominent bulls from the USA. The effect of this genetic influx in the Australian dairy cattle Population is poorly understood both in terms of diversity and local adaptation/divergence. This study uses 845 genome-wide SNP genetic markers and 431 bulls to characterize the level of genetic diversity and genetic divergence within the Australian and international Holstein Friesian dairy Population. No significant differences in genetic diversity (as measured by heterozygosity [H(o)] and allelic richness [A]) were observed over the 25-year time period (1975-1999) for bulls used in Australia. The importation of foreign semen into Australia has increased the effective Population size until it was in effect a sub-sample of the Global Population. Our data indicate that most individuals are equally closely related to one another, regardless of country of origin and year of birth. In effect, the Global Population can be considered as one single Population unit. These results indicate that inbreeding, genetic drift and selection has had little effect at reducing genetic diversity and differentiating the Australian Holstein Friesian Population at a genome-wide level.
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Genome‐wide genetic diversity of Holstein Friesian cattle reveals new insights into Australian and Global Population variability, including impact of selection
Animal genetics, 2007Co-Authors: Kyall R Zenger, Mehar S Khatkar, J A L Cavanagh, Rachel Hawken, H W RaadsmaAbstract:Past breeding strategies for dairy cattle have been very effective in producing rapid genetic gain to achieve industry targets and raise profitability. Such gains have been largely facilitated by intense selection of sires combined with the use of artificial insemination. However, this practice can potentially limit the level of genetic diversity through inbreeding and selection plateaus. The rate of inbreeding in Australia is increasing, primarily as a result of semen importation from a small number of prominent bulls from the USA. The effect of this genetic influx in the Australian dairy cattle Population is poorly understood both in terms of diversity and local adaptation/divergence. This study uses 845 genome-wide SNP genetic markers and 431 bulls to characterize the level of genetic diversity and genetic divergence within the Australian and international Holstein Friesian dairy Population. No significant differences in genetic diversity (as measured by heterozygosity [H(o)] and allelic richness [A]) were observed over the 25-year time period (1975-1999) for bulls used in Australia. The importation of foreign semen into Australia has increased the effective Population size until it was in effect a sub-sample of the Global Population. Our data indicate that most individuals are equally closely related to one another, regardless of country of origin and year of birth. In effect, the Global Population can be considered as one single Population unit. These results indicate that inbreeding, genetic drift and selection has had little effect at reducing genetic diversity and differentiating the Australian Holstein Friesian Population at a genome-wide level.
Wolfgang Lutz - One of the best experts on this subject based on the ideXlab platform.
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dimensions of Global Population projections what do we know about future Population trends and structures
Philosophical Transactions of the Royal Society B, 2010Co-Authors: Wolfgang Lutz, K C SamirAbstract:The total size of the world Population is likely to increase from its current 7 billion to 8–10 billion by 2050. This uncertainty is because of unknown future fertility and mortality trends in different parts of the world. But the young age structure of the Population and the fact that in much of Africa and Western Asia, fertility is still very high makes an increase by at least one more billion almost certain. Virtually, all the increase will happen in the developing world. For the second half of the century, Population stabilization and the onset of a decline are likely. In addition to the future size of the Population, its distribution by age, sex, level of educational attainment and place of residence are of specific importance for studying future food security. The paper provides a detailed discussion of different relevant dimensions in Population projections and an evaluation of the methods and assumptions used in current Global Population projections and in particular those produced by the United Nations and by IIASA.
Kyall R Zenger - One of the best experts on this subject based on the ideXlab platform.
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genome wide genetic diversity of holstein friesian cattle reveals new insights into australian and Global Population variability including impact of selection
Animal Genetics, 2007Co-Authors: Kyall R Zenger, Mehar S Khatkar, J A L Cavanagh, Rachel Hawken, H W RaadsmaAbstract:Past breeding strategies for dairy cattle have been very effective in producing rapid genetic gain to achieve industry targets and raise profitability. Such gains have been largely facilitated by intense selection of sires combined with the use of artificial insemination. However, this practice can potentially limit the level of genetic diversity through inbreeding and selection plateaus. The rate of inbreeding in Australia is increasing, primarily as a result of semen importation from a small number of prominent bulls from the USA. The effect of this genetic influx in the Australian dairy cattle Population is poorly understood both in terms of diversity and local adaptation/divergence. This study uses 845 genome-wide SNP genetic markers and 431 bulls to characterize the level of genetic diversity and genetic divergence within the Australian and international Holstein Friesian dairy Population. No significant differences in genetic diversity (as measured by heterozygosity [H(o)] and allelic richness [A]) were observed over the 25-year time period (1975-1999) for bulls used in Australia. The importation of foreign semen into Australia has increased the effective Population size until it was in effect a sub-sample of the Global Population. Our data indicate that most individuals are equally closely related to one another, regardless of country of origin and year of birth. In effect, the Global Population can be considered as one single Population unit. These results indicate that inbreeding, genetic drift and selection has had little effect at reducing genetic diversity and differentiating the Australian Holstein Friesian Population at a genome-wide level.
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Genome‐wide genetic diversity of Holstein Friesian cattle reveals new insights into Australian and Global Population variability, including impact of selection
Animal genetics, 2007Co-Authors: Kyall R Zenger, Mehar S Khatkar, J A L Cavanagh, Rachel Hawken, H W RaadsmaAbstract:Past breeding strategies for dairy cattle have been very effective in producing rapid genetic gain to achieve industry targets and raise profitability. Such gains have been largely facilitated by intense selection of sires combined with the use of artificial insemination. However, this practice can potentially limit the level of genetic diversity through inbreeding and selection plateaus. The rate of inbreeding in Australia is increasing, primarily as a result of semen importation from a small number of prominent bulls from the USA. The effect of this genetic influx in the Australian dairy cattle Population is poorly understood both in terms of diversity and local adaptation/divergence. This study uses 845 genome-wide SNP genetic markers and 431 bulls to characterize the level of genetic diversity and genetic divergence within the Australian and international Holstein Friesian dairy Population. No significant differences in genetic diversity (as measured by heterozygosity [H(o)] and allelic richness [A]) were observed over the 25-year time period (1975-1999) for bulls used in Australia. The importation of foreign semen into Australia has increased the effective Population size until it was in effect a sub-sample of the Global Population. Our data indicate that most individuals are equally closely related to one another, regardless of country of origin and year of birth. In effect, the Global Population can be considered as one single Population unit. These results indicate that inbreeding, genetic drift and selection has had little effect at reducing genetic diversity and differentiating the Australian Holstein Friesian Population at a genome-wide level.
Andrea M. Bernard - One of the best experts on this subject based on the ideXlab platform.
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Global Population genetic dynamics of a highly migratory apex predator shark
Molecular Ecology, 2016Co-Authors: Andrea M. Bernard, Michael R Heithaus, Sabine P Wintner, Kevin A Feldheim, Bradley M Wetherbee, Mahmood S. ShivjiAbstract:Knowledge of genetic connectivity dynamics in the world's large-bodied, highly migratory, apex predator sharks across their Global ranges is limited. One such species, the tiger shark (Galeocerdo cuvier), occurs worldwide in warm temperate and tropical waters, uses remarkably diverse habitats (nearshore to pelagic) and possesses a generalist diet that can structure marine ecosystems through top-down processes. We investigated the phylogeography and the Global Population structure of this exploited, phylogenetically enigmatic shark by using 10 nuclear microsatellites (n = 380) and sequences from the mitochondrial control region (CR, n = 340) and cytochrome oxidase I gene (n = 100). All three marker classes showed the genetic differentiation between tiger sharks from the western Atlantic and Indo-Pacific ocean basins (microsatellite FST > 0.129; CR ΦST > 0.497), the presence of North vs. southwestern Atlantic differentiation and the isolation of tiger sharks sampled from Hawaii from other surveyed locations. Furthermore, mitochondrial DNA revealed high levels of intraocean basin matrilineal Population structure, suggesting female philopatry and sex-biased gene flow. Coalescent- and genetic distance-based estimates of divergence from CR sequences were largely congruent (dcorr = 0.0015-0.0050), indicating a separation of Indo-Pacific and western Atlantic tiger sharks <1 million years ago. Mitochondrial haplotype relationships suggested that the western South Atlantic Ocean was likely a historical connection for interocean basin linkages via the dispersal around South Africa. Together, the results reveal unexpectedly high levels of Population structure in a highly migratory, behaviourally generalist, cosmopolitan ocean predator, calling for management and conservation on smaller-than-anticipated spatial scales.
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Global Population Genetic Dynamics of a Highly Migratory, Apex Predator Shark
Molecular Ecology, 2016Co-Authors: Andrea M. Bernard, Michael R Heithaus, Sabine P Wintner, Kevin A Feldheim, Bradley M WetherbeeAbstract:Knowledge of genetic connectivity dynamics in the world's large-bodied, highly migratory, apex predator sharks across their Global ranges is limited. One such species, the tiger shark (Galeocerdo cuvier), occurs worldwide in warm-temperate and tropical waters, uses remarkably diverse habitats (nearshore to pelagic), and possesses a generalist diet that can structure marine ecosystems through top down processes. We investigated the phylogeography and Global Population structure of this exploited, phylogenetically enigmatic shark by using 10 nuclear microsatellites (n = 380) and sequences from the mitochondrial control region (CR, n = 340) and cytochrome oxidase I gene (n = 100). All three marker classes showed genetic differentiation between tiger sharks from the western Atlantic and Indo-Pacific ocean basins (microsatellite FST > 0.129; CR ΦST > 0.497), the presence of North vs. South western Atlantic differentiation, and isolation of tiger sharks sampled from Hawaii from other surveyed locations. Furthermore, mitochondrial DNA revealed high levels of intra ocean-basin matrilineal Population structure, suggesting female philopatry and sex-biased gene flow. Coalescent- and genetic distance-based estimates of divergence from CR sequences were largely congruent (dcorr = 0.0015-0.0050), indicating a separation of Indo-Pacific and western Atlantic tiger sharks < 1 million years ago. Mitochondrial haplotype relationships suggested the western South Atlantic Ocean was likely a historical connection for inter-ocean basin linkages via dispersal around South Africa. Together, the results reveal unexpectedly high levels of Population structure in a highly migratory, behaviorally generalist, cosmopolitan ocean predator, calling for management and conservation on smaller than anticipated spatial scales. This article is protected by copyright. All rights reserved.
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Global Population genetic dynamics of a highly migratory, apex predator shark
Molecular ecology, 2016Co-Authors: Andrea M. Bernard, Michael R Heithaus, Sabine P Wintner, Kevin A Feldheim, Bradley M Wetherbee, Mahmood S. ShivjiAbstract:Knowledge of genetic connectivity dynamics in the world's large-bodied, highly migratory, apex predator sharks across their Global ranges is limited. One such species, the tiger shark (Galeocerdo cuvier), occurs worldwide in warm temperate and tropical waters, uses remarkably diverse habitats (nearshore to pelagic) and possesses a generalist diet that can structure marine ecosystems through top-down processes. We investigated the phylogeography and the Global Population structure of this exploited, phylogenetically enigmatic shark by using 10 nuclear microsatellites (n = 380) and sequences from the mitochondrial control region (CR, n = 340) and cytochrome oxidase I gene (n = 100). All three marker classes showed the genetic differentiation between tiger sharks from the western Atlantic and Indo-Pacific ocean basins (microsatellite FST > 0.129; CR ΦST > 0.497), the presence of North vs. southwestern Atlantic differentiation and the isolation of tiger sharks sampled from Hawaii from other surveyed locations. Furthermore, mitochondrial DNA revealed high levels of intraocean basin matrilineal Population structure, suggesting female philopatry and sex-biased gene flow. Coalescent- and genetic distance-based estimates of divergence from CR sequences were largely congruent (dcorr = 0.0015-0.0050), indicating a separation of Indo-Pacific and western Atlantic tiger sharks
Bradley M Wetherbee - One of the best experts on this subject based on the ideXlab platform.
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Global Population genetic dynamics of a highly migratory apex predator shark
Molecular Ecology, 2016Co-Authors: Andrea M. Bernard, Michael R Heithaus, Sabine P Wintner, Kevin A Feldheim, Bradley M Wetherbee, Mahmood S. ShivjiAbstract:Knowledge of genetic connectivity dynamics in the world's large-bodied, highly migratory, apex predator sharks across their Global ranges is limited. One such species, the tiger shark (Galeocerdo cuvier), occurs worldwide in warm temperate and tropical waters, uses remarkably diverse habitats (nearshore to pelagic) and possesses a generalist diet that can structure marine ecosystems through top-down processes. We investigated the phylogeography and the Global Population structure of this exploited, phylogenetically enigmatic shark by using 10 nuclear microsatellites (n = 380) and sequences from the mitochondrial control region (CR, n = 340) and cytochrome oxidase I gene (n = 100). All three marker classes showed the genetic differentiation between tiger sharks from the western Atlantic and Indo-Pacific ocean basins (microsatellite FST > 0.129; CR ΦST > 0.497), the presence of North vs. southwestern Atlantic differentiation and the isolation of tiger sharks sampled from Hawaii from other surveyed locations. Furthermore, mitochondrial DNA revealed high levels of intraocean basin matrilineal Population structure, suggesting female philopatry and sex-biased gene flow. Coalescent- and genetic distance-based estimates of divergence from CR sequences were largely congruent (dcorr = 0.0015-0.0050), indicating a separation of Indo-Pacific and western Atlantic tiger sharks <1 million years ago. Mitochondrial haplotype relationships suggested that the western South Atlantic Ocean was likely a historical connection for interocean basin linkages via the dispersal around South Africa. Together, the results reveal unexpectedly high levels of Population structure in a highly migratory, behaviourally generalist, cosmopolitan ocean predator, calling for management and conservation on smaller-than-anticipated spatial scales.
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Global Population Genetic Dynamics of a Highly Migratory, Apex Predator Shark
Molecular Ecology, 2016Co-Authors: Andrea M. Bernard, Michael R Heithaus, Sabine P Wintner, Kevin A Feldheim, Bradley M WetherbeeAbstract:Knowledge of genetic connectivity dynamics in the world's large-bodied, highly migratory, apex predator sharks across their Global ranges is limited. One such species, the tiger shark (Galeocerdo cuvier), occurs worldwide in warm-temperate and tropical waters, uses remarkably diverse habitats (nearshore to pelagic), and possesses a generalist diet that can structure marine ecosystems through top down processes. We investigated the phylogeography and Global Population structure of this exploited, phylogenetically enigmatic shark by using 10 nuclear microsatellites (n = 380) and sequences from the mitochondrial control region (CR, n = 340) and cytochrome oxidase I gene (n = 100). All three marker classes showed genetic differentiation between tiger sharks from the western Atlantic and Indo-Pacific ocean basins (microsatellite FST > 0.129; CR ΦST > 0.497), the presence of North vs. South western Atlantic differentiation, and isolation of tiger sharks sampled from Hawaii from other surveyed locations. Furthermore, mitochondrial DNA revealed high levels of intra ocean-basin matrilineal Population structure, suggesting female philopatry and sex-biased gene flow. Coalescent- and genetic distance-based estimates of divergence from CR sequences were largely congruent (dcorr = 0.0015-0.0050), indicating a separation of Indo-Pacific and western Atlantic tiger sharks < 1 million years ago. Mitochondrial haplotype relationships suggested the western South Atlantic Ocean was likely a historical connection for inter-ocean basin linkages via dispersal around South Africa. Together, the results reveal unexpectedly high levels of Population structure in a highly migratory, behaviorally generalist, cosmopolitan ocean predator, calling for management and conservation on smaller than anticipated spatial scales. This article is protected by copyright. All rights reserved.
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Global Population genetic dynamics of a highly migratory, apex predator shark
Molecular ecology, 2016Co-Authors: Andrea M. Bernard, Michael R Heithaus, Sabine P Wintner, Kevin A Feldheim, Bradley M Wetherbee, Mahmood S. ShivjiAbstract:Knowledge of genetic connectivity dynamics in the world's large-bodied, highly migratory, apex predator sharks across their Global ranges is limited. One such species, the tiger shark (Galeocerdo cuvier), occurs worldwide in warm temperate and tropical waters, uses remarkably diverse habitats (nearshore to pelagic) and possesses a generalist diet that can structure marine ecosystems through top-down processes. We investigated the phylogeography and the Global Population structure of this exploited, phylogenetically enigmatic shark by using 10 nuclear microsatellites (n = 380) and sequences from the mitochondrial control region (CR, n = 340) and cytochrome oxidase I gene (n = 100). All three marker classes showed the genetic differentiation between tiger sharks from the western Atlantic and Indo-Pacific ocean basins (microsatellite FST > 0.129; CR ΦST > 0.497), the presence of North vs. southwestern Atlantic differentiation and the isolation of tiger sharks sampled from Hawaii from other surveyed locations. Furthermore, mitochondrial DNA revealed high levels of intraocean basin matrilineal Population structure, suggesting female philopatry and sex-biased gene flow. Coalescent- and genetic distance-based estimates of divergence from CR sequences were largely congruent (dcorr = 0.0015-0.0050), indicating a separation of Indo-Pacific and western Atlantic tiger sharks