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Larissa Rosa De Oliveira - One of the best experts on this subject based on the ideXlab platform.
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status Population Trend and genetic structure of south american fur seals arctocephalus australis in southwestern atlantic waters
Marine Mammal Science, 2015Co-Authors: Enrique A Crespo, Adrian Schiavini, Nestor A Garcia, Valentina Francotrecu, Natalie R P Goodall, Diego Rodriguez, Joao Stenghel Morgante, Larissa Rosa De OliveiraAbstract:The South American fur seal (SAFS), Arctocephalus australis, was severely depleted during the 18th century. This work updates information on distribution, abundance, seasonal movements, and genetic structure along the southwestern South Atlantic. Its distribution in Argentine waters includes nineteen rookeries on the Patagonian coast, Isla de los Estados, and islets of the Beagle Channel. Censuses were carried out in rookeries from Isla Escondida to Isla de los Estados from 1996 to 2014. The largest concentrations are found in Chubut, (4,500–15,500 seals) and Isla de los Estados (4,500). Pups were recorded on Isla Escondida, Rasa, and Isla de los Estados. An increasing number of SAFS were recorded in northern Patagonia, including seals marked in Uruguay. Skin samples were taken from southern Brazil to Tierra del Fuego in order to evaluate Population structure and demographic Trends. Genetic results indicated no Population subdivisions (Φst = −0.0292, Fst = −0.00716, P > 0.05). Bayesian skyline plots constructed for the entire data set indicated evidence of rapid Population expansion discernible in Nef between the last 20,000 and 17,000 yr. Genetics results and observation data from marked fur seals support the hypothesis of ancient gene flow and a single Atlantic Population. Therefore, SAFS should be managed under international and integrated conservation policies.
Pamela Parker - One of the best experts on this subject based on the ideXlab platform.
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RESEARCH ARTICLE Population Trend and Elasticities of Vital Rates for Steller Sea Lions (Eumetopias jubatus) in the Eastern Gulf of Alaska: A New Life-History Table Analysis
2016Co-Authors: John M. Maniscalco, Alan M. Springer, Milo D. Adkison, Pamela ParkerAbstract:Steller sea lion (Eumetopias jubatus) numbers are beginning to recover across most of the western distinct Population segment following catastrophic declines that began in the 1970s and ended around the turn of the century. This study makes use of contemporary vital rate estimates from a Trend-site rookery in the eastern Gulf of Alaska (a sub-region of the west-ern Population) in a matrix Population model to estimate the Trend and strength of the recov-ery across this region between 2003 and 2013. The modeled Population Trend was projected into the future based on observed variation in vital rates and a prospective elastic-ity analysis was conducted to determine future Trends and which vital rates pose the great-est threats to recovery. The modeled Population grew at a mean rate of 3.5 % per yr between 2003 and 2013 and was correlated with census count data from the local rookery and throughout the eastern Gulf of Alaska. If recent vital rate estimates continue with little change, the eastern Gulf of Alaska Population could be fully recovered to pre-decline levels within 23 years. With density dependent growth, the Population would need another 45 years to fully recover. Elasticity analysis showed that, as expected, Population growth rate (λ) was most sensitive to changes in adult survival, less sensitive to changes in juvenile sur-vival, and least sensitive to changes in fecundity. A Population decline could be expected with only a 6 % decrease in adult survival, whereas a 32 % decrease in fecundity would be necessary to bring about a Population decline. These results have important implications for Population management and suggest current research priorities should be shifted to a greater emphasis on survival rates and causes of mortality
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Population Trend and Elasticities of Vital Rates for Steller Sea Lions (Eumetopias jubatus) in the Eastern Gulf of Alaska: A New Life-History Table Analysis
PloS one, 2015Co-Authors: John M. Maniscalco, Alan M. Springer, Milo D. Adkison, Pamela ParkerAbstract:Steller sea lion (Eumetopias jubatus) numbers are beginning to recover across most of the western distinct Population segment following catastrophic declines that began in the 1970s and ended around the turn of the century. This study makes use of contemporary vital rate estimates from a Trend-site rookery in the eastern Gulf of Alaska (a sub-region of the western Population) in a matrix Population model to estimate the Trend and strength of the recovery across this region between 2003 and 2013. The modeled Population Trend was projected into the future based on observed variation in vital rates and a prospective elasticity analysis was conducted to determine future Trends and which vital rates pose the greatest threats to recovery. The modeled Population grew at a mean rate of 3.5% per yr between 2003 and 2013 and was correlated with census count data from the local rookery and throughout the eastern Gulf of Alaska. If recent vital rate estimates continue with little change, the eastern Gulf of Alaska Population could be fully recovered to pre-decline levels within 23 years. With density dependent growth, the Population would need another 45 years to fully recover. Elasticity analysis showed that, as expected, Population growth rate (λ) was most sensitive to changes in adult survival, less sensitive to changes in juvenile survival, and least sensitive to changes in fecundity. A Population decline could be expected with only a 6% decrease in adult survival, whereas a 32% decrease in fecundity would be necessary to bring about a Population decline. These results have important implications for Population management and suggest current research priorities should be shifted to a greater emphasis on survival rates and causes of mortality.
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Population Trend and Elasticities of Vital Rates for Steller Sea Lions (Eumetopias jubatus - Fig 4 ) in the Eastern Gulf of Alaska: A New Life-History Table Analysis
2015Co-Authors: John M. Maniscalco, Alan M. Springer, Milo D. Adkison, Pamela ParkerAbstract:(a) Density-independent projections (95% C.I.) of the Steller sea lion Population in the eastern Gulf of Alaska based on bootstrapped values of fecundity and survival observed over the years 2003–2012. (b) Projected Population Trend (95% C.I.) for Steller sea lions in the eastern Gulf of Alaska based on an intrinsic rate of increase of r = 0.059 and carrying capacity of K = 10,000 age 1+ males and females.
John M. Maniscalco - One of the best experts on this subject based on the ideXlab platform.
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RESEARCH ARTICLE Population Trend and Elasticities of Vital Rates for Steller Sea Lions (Eumetopias jubatus) in the Eastern Gulf of Alaska: A New Life-History Table Analysis
2016Co-Authors: John M. Maniscalco, Alan M. Springer, Milo D. Adkison, Pamela ParkerAbstract:Steller sea lion (Eumetopias jubatus) numbers are beginning to recover across most of the western distinct Population segment following catastrophic declines that began in the 1970s and ended around the turn of the century. This study makes use of contemporary vital rate estimates from a Trend-site rookery in the eastern Gulf of Alaska (a sub-region of the west-ern Population) in a matrix Population model to estimate the Trend and strength of the recov-ery across this region between 2003 and 2013. The modeled Population Trend was projected into the future based on observed variation in vital rates and a prospective elastic-ity analysis was conducted to determine future Trends and which vital rates pose the great-est threats to recovery. The modeled Population grew at a mean rate of 3.5 % per yr between 2003 and 2013 and was correlated with census count data from the local rookery and throughout the eastern Gulf of Alaska. If recent vital rate estimates continue with little change, the eastern Gulf of Alaska Population could be fully recovered to pre-decline levels within 23 years. With density dependent growth, the Population would need another 45 years to fully recover. Elasticity analysis showed that, as expected, Population growth rate (λ) was most sensitive to changes in adult survival, less sensitive to changes in juvenile sur-vival, and least sensitive to changes in fecundity. A Population decline could be expected with only a 6 % decrease in adult survival, whereas a 32 % decrease in fecundity would be necessary to bring about a Population decline. These results have important implications for Population management and suggest current research priorities should be shifted to a greater emphasis on survival rates and causes of mortality
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Population Trend and Elasticities of Vital Rates for Steller Sea Lions (Eumetopias jubatus) in the Eastern Gulf of Alaska: A New Life-History Table Analysis
PloS one, 2015Co-Authors: John M. Maniscalco, Alan M. Springer, Milo D. Adkison, Pamela ParkerAbstract:Steller sea lion (Eumetopias jubatus) numbers are beginning to recover across most of the western distinct Population segment following catastrophic declines that began in the 1970s and ended around the turn of the century. This study makes use of contemporary vital rate estimates from a Trend-site rookery in the eastern Gulf of Alaska (a sub-region of the western Population) in a matrix Population model to estimate the Trend and strength of the recovery across this region between 2003 and 2013. The modeled Population Trend was projected into the future based on observed variation in vital rates and a prospective elasticity analysis was conducted to determine future Trends and which vital rates pose the greatest threats to recovery. The modeled Population grew at a mean rate of 3.5% per yr between 2003 and 2013 and was correlated with census count data from the local rookery and throughout the eastern Gulf of Alaska. If recent vital rate estimates continue with little change, the eastern Gulf of Alaska Population could be fully recovered to pre-decline levels within 23 years. With density dependent growth, the Population would need another 45 years to fully recover. Elasticity analysis showed that, as expected, Population growth rate (λ) was most sensitive to changes in adult survival, less sensitive to changes in juvenile survival, and least sensitive to changes in fecundity. A Population decline could be expected with only a 6% decrease in adult survival, whereas a 32% decrease in fecundity would be necessary to bring about a Population decline. These results have important implications for Population management and suggest current research priorities should be shifted to a greater emphasis on survival rates and causes of mortality.
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Population Trend and Elasticities of Vital Rates for Steller Sea Lions (Eumetopias jubatus - Fig 4 ) in the Eastern Gulf of Alaska: A New Life-History Table Analysis
2015Co-Authors: John M. Maniscalco, Alan M. Springer, Milo D. Adkison, Pamela ParkerAbstract:(a) Density-independent projections (95% C.I.) of the Steller sea lion Population in the eastern Gulf of Alaska based on bootstrapped values of fecundity and survival observed over the years 2003–2012. (b) Projected Population Trend (95% C.I.) for Steller sea lions in the eastern Gulf of Alaska based on an intrinsic rate of increase of r = 0.059 and carrying capacity of K = 10,000 age 1+ males and females.
G Siriwardena - One of the best experts on this subject based on the ideXlab platform.
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temporal variation in the annual survival rates of six granivorous birds with contrasting Population Trends
Ibis, 2008Co-Authors: Stephen R Baillie, G Siriwardena, Jeremy D WilsonAbstract:To identify the environmental changes responsible for the declines in abundance shown by many granivorous bird species, the demographic mechanism through which the changes have acted must be determined. Ring-recovery data were used to estimate the annual survival rates (since 1962) of six seed-eating bird species with contrasting Population Trends to identify whether variations in survival could have been the mechanism behind Population change. The survival rates of Bullfinch Pyrrhula pyrrhula, Chaffinch Fringilla coelebs, Goldfinch Carduelis carduelis, Greenfinch C. choris, Linnet C. cannabina and House Sparrow Passer domesticus were estimated using models allowing age- and time-specificity in survival (reporting rates could be assumed to be constant). Three tests of the importance of variations in survival in determining Population Trend were conducted: (1) simple Population models with constant productivity showed whether temporal changes in survival were sufficient alone to explain observed Trends in abundance, (2) survival models incorporating changes in abundance as a covariate identified whether annual survival rates were associated with Population changes, and (3) mean survival rates found in objectively identified periods of increase, decline and stability in each species' Population Trend were compared. These analyses suggested that environmental change has led to the observed Population Trends for Goldfinch and House Sparrow largely through effects on survival. Weaker relationships between variations in survival and Population Trend were found for Bullfinch, Chaffinch and Linnet, but other factors such as breeding success are likely to have been at least as important for these species, and also for Greenfinch. Checking analyses incorporating density-dependence did not alter these conclusions.
Enrique A Crespo - One of the best experts on this subject based on the ideXlab platform.
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status Population Trend and genetic structure of south american fur seals arctocephalus australis in southwestern atlantic waters
Marine Mammal Science, 2015Co-Authors: Enrique A Crespo, Adrian Schiavini, Nestor A Garcia, Valentina Francotrecu, Natalie R P Goodall, Diego Rodriguez, Joao Stenghel Morgante, Larissa Rosa De OliveiraAbstract:The South American fur seal (SAFS), Arctocephalus australis, was severely depleted during the 18th century. This work updates information on distribution, abundance, seasonal movements, and genetic structure along the southwestern South Atlantic. Its distribution in Argentine waters includes nineteen rookeries on the Patagonian coast, Isla de los Estados, and islets of the Beagle Channel. Censuses were carried out in rookeries from Isla Escondida to Isla de los Estados from 1996 to 2014. The largest concentrations are found in Chubut, (4,500–15,500 seals) and Isla de los Estados (4,500). Pups were recorded on Isla Escondida, Rasa, and Isla de los Estados. An increasing number of SAFS were recorded in northern Patagonia, including seals marked in Uruguay. Skin samples were taken from southern Brazil to Tierra del Fuego in order to evaluate Population structure and demographic Trends. Genetic results indicated no Population subdivisions (Φst = −0.0292, Fst = −0.00716, P > 0.05). Bayesian skyline plots constructed for the entire data set indicated evidence of rapid Population expansion discernible in Nef between the last 20,000 and 17,000 yr. Genetics results and observation data from marked fur seals support the hypothesis of ancient gene flow and a single Atlantic Population. Therefore, SAFS should be managed under international and integrated conservation policies.