The Experts below are selected from a list of 14703 Experts worldwide ranked by ideXlab platform
David O Conover - One of the best experts on this subject based on the ideXlab platform.
-
circulating levels of plasma igf i during recovery from size selective harvesting in menidia menidia
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2013Co-Authors: Tara A. Duffy, Matthew E. Picha, Russell J. Borski, David O ConoverAbstract:Abstract Selection for Growth-related traits in domesticated fishes often results in predictable changes within the Growth hormone-insulin-like Growth factor (GH-IGF-1) axis. Little is known about the mechanisms controlling changes in Growth capacity resulting from fishery-induced evolution. We took advantage of a long-term study where Menidia menidia were selected for size at age over multiple generations to mimic fisheries-induced selection. This selection regime produced three populations with significant differences in Intrinsic Growth Rate. These Growth differences partially rebounded, but persisted even after selection was relaxed, resulting in fast, intermediate, and slow-growing lines. Plasma IGF-1 was measured in these populations as a potential target of selection on Growth. IGF-1 was significantly correlated with current length and mass, and was positively correlated with Growth Rate (g d −1 ) in two lines, indicating it may be an appropriate indicator of Growth capacity. The slow-growing line exhibited higher overall IGF-1 levels relative to the depressed IGF-1 seen in the fast-growing line, contrary to our prediction. We offer possible explanations for this unusual pattern and argue that somatic Growth is likely to be under control of mechanism(s) downstream to IGF-1. IGF-1 provides an interesting basis for understanding endocrine control of Growth in response to artificial selection and recovery.
-
circulating levels of plasma igf i during recovery from size selective harvesting in menidia menidia part a molecular integrative physiology
Comparative Biochemistry and Physiology, 2013Co-Authors: Tara A. Duffy, Matthew E. Picha, Russell J. Borski, David O ConoverAbstract:Selection for Growth-related traits in domesticated fishes often results in predictable changes within the Growth hormone-insulin-like Growth factor (GH-IGF-1) axis. Little is known about the mechanisms controlling changes in Growth capacity resulting from fishery-induced evolution. We took advantage of a long-term study where Menidia menidia were selected for size at age over multiple generations to mimic fisheries-induced selection. This selection regime produced three populations with significant differences in Intrinsic Growth Rate. These Growth differences partially rebounded, but persisted even after selection was relaxed, resulting in fast, intermediate, and slow-growing lines. Plasma IGF-1 was measured in these populations as a potential target of selection on Growth. IGF-1 was significantly correlated with current length and mass, and was positively correlated with Growth Rate (g d−1) in two lines, indicating it may be an appropriate indicator of Growth capacity. The slow-growing line exhibited higher overall IGF-1 levels relative to the depressed IGF-1 seen in the fast-growing line, contrary to our prediction. We offer possible explanations for this unusual pattern and argue that somatic Growth is likely to be under control of mechanism(s) downstream to IGF-1. IGF-1 provides an interesting basis for understanding endocrine control of Growth in response to artificial selection and recovery.
-
coevolution of foraging behavior with Intrinsic Growth Rate risk taking in naturally and artificially selected Growth genotypes of menidia menidia
Oecologia, 2007Co-Authors: Stephen A Arnott, Susumu Chiba, David O ConoverAbstract:Although there is accumulating evidence of Growth-Rate optimization by natural selection, the coevolution of Growth Rate and risk-taking behavior has not been sufficiently documented. The Atlantic silverside fish, Menidia menidia, displays countergradient variation in Growth across a latitudinal gradient: genotypes from Nova Scotia (NS), for example, grow in length twofold faster than those from South Carolina (SC). Past work has established that fast Growth is adaptive in northern climates, but the trade-off is poorer swimming performance and higher susceptibility to predators. We compared escape behavior and willingness to forage under threat of predation among Growth genotypes reared and tested under common-garden conditions. When chased with a predator model, NS fish occupied shelter more quickly than SC fish. When food was supplied after a chase, NS fish reemerged from the shelter much more quickly than SC fish and immediately commenced feeding, whereas many SC fish displayed timid behavior and did not feed. When food was absent following a chase, however, NS fish remained in the shelter longer than did SC fish and both displayed timid behavior. Hence, the fast-growing NS genotype was bolder than SC fish in the presence of food, but shyer in the absence of food. These behaviors are adaptive given the physiological constraints Intrinsic to each genotype. Experiments on captive populations of silversides that had been artificially selected for fast or slow Growth confirmed that foraging behavior is genetically correlated with Intrinsic Growth Rate, although in these trials the fast-Growth genotype was always more bold, regardless of food availability, as would be expected in the absence of predators. We conclude that risk-taking foraging behavior coevolves adaptively with Intrinsic Growth Rate in M. menidia.
-
evolution of Intrinsic Growth Rate metabolic costs drive trade offs between Growth and swimming performance in menidia menidia
Evolution, 2006Co-Authors: Stephen A Arnott, Susumu Chiba, David O ConoverAbstract:There is strong evidence that genetic capacity for Growth evolves toward an optimum rather than an absolute maximum. This implies that fast Growth has a cost and that trade-offs occur between Growth and other life-history traits, but the fundamental mechanisms are poorly understood. Previous work on the Atlantic silverside fish Menidia menidia has demonstRated a trade-off between Growth and swimming performance. We hypothesize that the trade-off derives from the competing metabolic demands associated with Growth and swimming activity. We tested this by measuring standard metabolic Rate (MSTD), maximum sustainable metabolic Rate (MACT) and metabolic scope of lab- oratory-reared silversides originating from two geographically distinct populations with well-documented differences in genetic capacity for Growth. The fast-Growth genotype had a significantly greater MSTD than the slow-Growth genotype, but a similar MACT when swum to near exhaustion. The scope for activity of the fast-Growth genotype was lower than that of the slow-Growth genotype. Furthermore, the fast-Growth genotype eats larger meals, thereby incurring a greater postprandial oxygen demand. We conclude that a metabolic trade-off occurs between Growth and other metabolic demands and that this trade-off provides a general mechanism underlying the evolution of Growth Rate.
Mingxin Wang - One of the best experts on this subject based on the ideXlab platform.
-
a diffusive logistic equation with a free boundary and sign changing coefficient in time periodic environment
Journal of Functional Analysis, 2016Co-Authors: Mingxin WangAbstract:Abstract This paper concerns a diffusive logistic equation with a free boundary and sign-changing Intrinsic Growth Rate in heterogeneous time-periodic environment, in which the variable Intrinsic Growth Rate may be “very negative” in a “suitable large region” (see conditions (H1) , (H2) , (4.3) ). Such a model can be used to describe the spreading of a new or invasive species, with the free boundary representing the expanding front. In the case of higher space dimensions with radial symmetry and when the Intrinsic Growth Rate has a positive lower bound, this problem has been studied by Du, Guo & Peng [11] . They established a spreading–vanishing dichotomy, the sharp criteria for spreading and vanishing and estimate of the asymptotic spreading speed. In the present paper, we show that the above results are retained for our problem.
-
a diffusive logistic equation with a free boundary and sign changing coefficient in time periodic environment
arXiv: Analysis of PDEs, 2015Co-Authors: Mingxin WangAbstract:This paper concerns a diffusive logistic equation with a free boundary and sign-changing Intrinsic Growth Rate in heterogeneous time-periodic environment, in which the variable Intrinsic Growth Rate may be "very negative" in a "suitable large region". Such a model can be used to describe the spreading of a new or invasive species, with the free boundary representing the expanding front. In the case of higher space dimensions with radial symmetry and the Intrinsic Growth Rate has a positive lower bound, this problem has been studied by Du, Guo and Peng . They established a spreading-vanishing dichotomy, the sharp criteria for spreading and vanishing and estimate of the asymptotic spreading speed. In the present paper, we show that the above results are retained for our problem. This paper has been submitted to Journal of Functional Analysis in August 5, 2014 (JFA-14-548).
-
effect of a protection zone in the diffusive leslie predator prey model
Journal of Differential Equations, 2009Co-Authors: Rui Peng, Mingxin WangAbstract:Abstract In this paper, we consider the diffusive Leslie predator–prey model with large Intrinsic predator Growth Rate, and investigate the change of behavior of the model when a simple protection zone Ω 0 for the prey is introduced. As in earlier work [Y. Du, J. Shi, A diffusive predator–prey model with a protection zone, J. Differential Equations 229 (2006) 63–91; Y. Du, X. Liang, A diffusive competition model with a protection zone, J. Differential Equations 244 (2008) 61–86] we show the existence of a critical patch size of the protection zone, determined by the first Dirichlet eigenvalue of the Laplacian over Ω 0 and the Intrinsic Growth Rate of the prey, so that there is fundamental change of the dynamical behavior of the model only when Ω 0 is above the critical patch size. However, our research here reveals significant difference of the model's behavior from the predator–prey model studied in [Y. Du, J. Shi, A diffusive predator–prey model with a protection zone, J. Differential Equations 229 (2006) 63–91] with the same kind of protection zone. We show that the asymptotic profile of the population distribution of the Leslie model is governed by a standard boundary blow-up problem, and classical or degeneRate logistic equations.
Susumu Chiba - One of the best experts on this subject based on the ideXlab platform.
-
coevolution of foraging behavior with Intrinsic Growth Rate risk taking in naturally and artificially selected Growth genotypes of menidia menidia
Oecologia, 2007Co-Authors: Stephen A Arnott, Susumu Chiba, David O ConoverAbstract:Although there is accumulating evidence of Growth-Rate optimization by natural selection, the coevolution of Growth Rate and risk-taking behavior has not been sufficiently documented. The Atlantic silverside fish, Menidia menidia, displays countergradient variation in Growth across a latitudinal gradient: genotypes from Nova Scotia (NS), for example, grow in length twofold faster than those from South Carolina (SC). Past work has established that fast Growth is adaptive in northern climates, but the trade-off is poorer swimming performance and higher susceptibility to predators. We compared escape behavior and willingness to forage under threat of predation among Growth genotypes reared and tested under common-garden conditions. When chased with a predator model, NS fish occupied shelter more quickly than SC fish. When food was supplied after a chase, NS fish reemerged from the shelter much more quickly than SC fish and immediately commenced feeding, whereas many SC fish displayed timid behavior and did not feed. When food was absent following a chase, however, NS fish remained in the shelter longer than did SC fish and both displayed timid behavior. Hence, the fast-growing NS genotype was bolder than SC fish in the presence of food, but shyer in the absence of food. These behaviors are adaptive given the physiological constraints Intrinsic to each genotype. Experiments on captive populations of silversides that had been artificially selected for fast or slow Growth confirmed that foraging behavior is genetically correlated with Intrinsic Growth Rate, although in these trials the fast-Growth genotype was always more bold, regardless of food availability, as would be expected in the absence of predators. We conclude that risk-taking foraging behavior coevolves adaptively with Intrinsic Growth Rate in M. menidia.
-
evolution of Intrinsic Growth Rate metabolic costs drive trade offs between Growth and swimming performance in menidia menidia
Evolution, 2006Co-Authors: Stephen A Arnott, Susumu Chiba, David O ConoverAbstract:There is strong evidence that genetic capacity for Growth evolves toward an optimum rather than an absolute maximum. This implies that fast Growth has a cost and that trade-offs occur between Growth and other life-history traits, but the fundamental mechanisms are poorly understood. Previous work on the Atlantic silverside fish Menidia menidia has demonstRated a trade-off between Growth and swimming performance. We hypothesize that the trade-off derives from the competing metabolic demands associated with Growth and swimming activity. We tested this by measuring standard metabolic Rate (MSTD), maximum sustainable metabolic Rate (MACT) and metabolic scope of lab- oratory-reared silversides originating from two geographically distinct populations with well-documented differences in genetic capacity for Growth. The fast-Growth genotype had a significantly greater MSTD than the slow-Growth genotype, but a similar MACT when swum to near exhaustion. The scope for activity of the fast-Growth genotype was lower than that of the slow-Growth genotype. Furthermore, the fast-Growth genotype eats larger meals, thereby incurring a greater postprandial oxygen demand. We conclude that a metabolic trade-off occurs between Growth and other metabolic demands and that this trade-off provides a general mechanism underlying the evolution of Growth Rate.
Stephen A Arnott - One of the best experts on this subject based on the ideXlab platform.
-
coevolution of foraging behavior with Intrinsic Growth Rate risk taking in naturally and artificially selected Growth genotypes of menidia menidia
Oecologia, 2007Co-Authors: Stephen A Arnott, Susumu Chiba, David O ConoverAbstract:Although there is accumulating evidence of Growth-Rate optimization by natural selection, the coevolution of Growth Rate and risk-taking behavior has not been sufficiently documented. The Atlantic silverside fish, Menidia menidia, displays countergradient variation in Growth across a latitudinal gradient: genotypes from Nova Scotia (NS), for example, grow in length twofold faster than those from South Carolina (SC). Past work has established that fast Growth is adaptive in northern climates, but the trade-off is poorer swimming performance and higher susceptibility to predators. We compared escape behavior and willingness to forage under threat of predation among Growth genotypes reared and tested under common-garden conditions. When chased with a predator model, NS fish occupied shelter more quickly than SC fish. When food was supplied after a chase, NS fish reemerged from the shelter much more quickly than SC fish and immediately commenced feeding, whereas many SC fish displayed timid behavior and did not feed. When food was absent following a chase, however, NS fish remained in the shelter longer than did SC fish and both displayed timid behavior. Hence, the fast-growing NS genotype was bolder than SC fish in the presence of food, but shyer in the absence of food. These behaviors are adaptive given the physiological constraints Intrinsic to each genotype. Experiments on captive populations of silversides that had been artificially selected for fast or slow Growth confirmed that foraging behavior is genetically correlated with Intrinsic Growth Rate, although in these trials the fast-Growth genotype was always more bold, regardless of food availability, as would be expected in the absence of predators. We conclude that risk-taking foraging behavior coevolves adaptively with Intrinsic Growth Rate in M. menidia.
-
evolution of Intrinsic Growth Rate metabolic costs drive trade offs between Growth and swimming performance in menidia menidia
Evolution, 2006Co-Authors: Stephen A Arnott, Susumu Chiba, David O ConoverAbstract:There is strong evidence that genetic capacity for Growth evolves toward an optimum rather than an absolute maximum. This implies that fast Growth has a cost and that trade-offs occur between Growth and other life-history traits, but the fundamental mechanisms are poorly understood. Previous work on the Atlantic silverside fish Menidia menidia has demonstRated a trade-off between Growth and swimming performance. We hypothesize that the trade-off derives from the competing metabolic demands associated with Growth and swimming activity. We tested this by measuring standard metabolic Rate (MSTD), maximum sustainable metabolic Rate (MACT) and metabolic scope of lab- oratory-reared silversides originating from two geographically distinct populations with well-documented differences in genetic capacity for Growth. The fast-Growth genotype had a significantly greater MSTD than the slow-Growth genotype, but a similar MACT when swum to near exhaustion. The scope for activity of the fast-Growth genotype was lower than that of the slow-Growth genotype. Furthermore, the fast-Growth genotype eats larger meals, thereby incurring a greater postprandial oxygen demand. We conclude that a metabolic trade-off occurs between Growth and other metabolic demands and that this trade-off provides a general mechanism underlying the evolution of Growth Rate.
Chial Belgis - One of the best experts on this subject based on the ideXlab platform.
-
cyst based toxicity tests xi influence of the type of food on the Intrinsic Growth Rate of the rotifer brachionus calyciflorus in short chronic toxicity tests
Chemosphere, 2003Co-Authors: Chial Belgis, Persoone GuidoAbstract:Abstract As important members of zooplankton communities worldwide, rotifers are used extensively in ecotoxicological research. Chronic rotifer tests are, however, dependent on live algal food which adds to the complexity, the variability and the costs of these bioassays. To bypass the former problem, experiments have been undertaken with the freshwater rotifer Brachionus calyciflorus , to determine their Intrinsic Growth Rate ( r ) when fed for 48 h on a mixture of green algae ( Raphidocelis subcapitata recently renamed Pseudokirchneriella subcapitata ) obtained from algal beads stored for different periods of time, and other inert foods. All tests have been performed in disposable multiwells, in 1 ml cups each inoculated with 1 rotifer freshly hatched from dried cysts. The majority of the Growth tests was performed in eight replicates. The investigations revealed that microalgae from algal beads stored for up to one year, in darkness, at 4 °C, supplemented with dried blue–green algae ( Spirulina ) gave satisfactory rotifer reproduction. The Intrinsic Growth Rates of the rotifers, were, however, dependent on the storage time of the algal beads; the highests r ’s (0.7–0.8) were obtained with algae from beads not older than four months. Growth tests with combinations of P. subcapitata and other inert feeds revealed that the enrichment food Selco used in aquaculture, also gave the same reproductive output as the combination microalgae/ Spirulina . A rotifer Growth experiment with 18 replicates showed that the variation coefficient is below 20% when the tests comprise eight replicates. This study demonstRated that microalgae from beads, supplemented by other inert food, open the door for a practical and cost-effective short-chronic rotifer test, which is totally independent of the culturing of both the test species and its live food.
