Phenotypic plasticity of relative investment in shell, eggs, and somatic tissue was examined with... more Phenotypic plasticity of relative investment in shell, eggs, and somatic tissue was examined with experimental population density manipulations in field populations of the intertidal barnacles Semibalanus (Balanus) balanoides from Massachusetts and Balanus glandula and Chthamalus dalli from Washington State, U.S.A. Individuals of S. balanoides of comparable somatic tissue weights produced larger clutches of eggs when crowded and columnar than when conical and uncrowded. Individuals of C. dalli showed a similar pattern. Individuals of B. glandula showed the opposite pattern: at comparable somatic tissue weights, conical uncrowded individuals made slightly larger clutches of eggs than did crowded, columnar individuals. In all cases the greatest shell investment per unit somatic tissue weight was associated with the greatest clutch investment per unit somatic tissue weight.
NOAH LSM Mussel v2.0 is a mathematical model that predicts mussel bed temperatures from atmospher... more NOAH LSM Mussel v2.0 is a mathematical model that predicts mussel bed temperatures from atmospheric and oceanic data by mimicking the thermal properties of a mussel bed exposed to tidal inundation and wave run-up. The model is derived from the National Weather Service NOAH Land Surface Model. In v2.0, it is possible to change the within mussel bed contact which determines conductive heat transfer. Mussel survival is predicted using mussel bed temperatures from the model. Please cite the following papers if you use this code: <strong>NOAH LSM Mussel v2.0</strong> Mislan, KAS and DS Wethey. 2015. A biophysical basis for patchy mortality during heat waves. Ecology. 96:902-907 http://dx.doi.org/10.1890/14-1219.1 <strong>NOAH_LSM_Mussel_v1.0</strong> Wethey DS, LD Brin, B Helmuth, and KAS Mislan. 2011. Predicting intertidal organism temperatures with modified land surface models. Ecological Modelling 222:3568-3576. http://dx.doi.org/10.1016/j.ecolmodel.2011.08.019 <strong>NOAH_LSM</strong> Chen F, and J Dudhia. 2001. Coupling an advanced land surface-hydrology model with the Penn State-NCAR MM5 modeling system. Part I: Model implementation and sensitivity. Monthly Weather Review, 129:569-585. Ek MB, Mitchell KE, Lin Y, Rogers E, Grunmann P, Koren V, and JD Tarpley. 2003. Implementation of Noah land surface model advances in the National Centers for Environmental Prediction operational mesoscale Eta model. Journal of Geophysical Research: Atmospheres (1984–2012), 108(D22). http://dx.doi.org/10.1029/2002JD003296
According to the selfish herd hypothesis, animals can decrease predation risk by moving toward on... more According to the selfish herd hypothesis, animals can decrease predation risk by moving toward one another if the predator can appear anywhere and will attack the nearest target. Previous studies have shown that aggregations can form using simple movement rules designed to decrease each animal&#39;s Domain of Danger. However, if the predator attacks from outside the group&#39;s perimeter, these simple movement rules might not lead to aggregation. To test whether simple selfish movement rules would decrease predation risk for those situations when the predator attacks from outside the flock perimeter, we constructed a computer model that allowed flocks of 75 simulated fiddler crabs to react to one another, and to a predator attacking from 7 m away. We attacked simulated crab flocks with predators of different sizes and attack speeds, and computed relative predation risk after 120 time steps. Final trajectories showed flight toward the center of the flock, but curving away from the predator. Path curvature depended on the predator&#39;s size and approach speed. The average crab experienced a greater decrease in predation risk when the predator was small or slow moving. Regardless of the predator&#39;s size and speed, however, predation risk always decreased as long as crabs took their flock-mates into account. We conclude that, even when flight away from an external predator occurs, the selfish avoidance of danger can lead to aggregation.
Geographic limits of species are commonly associated with climatic or physical boundaries, but th... more Geographic limits of species are commonly associated with climatic or physical boundaries, but the mechanisms of exclusion at the limits of distribution are poorly understood. In some intertidal populations, the strengths of interactions with natural enemies are mediated by microclimate, and determine geographic limits. The northern limit of the barnacle Chthamalus fragilis in New England is the south side of Cape Cod, Massachusetts. South of the cape, Chthamalus has a refuge from competition in the high intertidal, which is too hot for survival of its superior competitor Semibalanus balanoides. North of the cape, the high intertidal is cooler, and Semibalanus survives, so Chthamalus has no refuge. Thus, geographic variation in the strength of competition may determine the geographic limit of Chthamalus. Intolerance of cold by Chthamalus cannot account for the geographic limit: transplants of Chthamalus 80 km beyond its northern limit survived up to 8 yr in the absence of competition with Semibalanus. At the geographic limit of Chthamalus in the Cape Cod Canal there are two bridges, 5 km apart. On the southern bridge, Chthamalus is abundant and occupies a refuge above Semibalanus. On the northern bridge in 2001, only 7 individual Chthamalus were present. Despite the proximity of the bridges, their microclimates are very different. The southern bridge, where Chthamalus is abundant, is up to 8°C hotter than the northern bridge. This higher temperature creates a refuge in the high intertidal for Chthamalus. On the cooler northern bridge, there is no refuge for Chthamalus. Because of the difference in temperatures of the water masses that meet in the canal, heat storage in the rock of the bridge piers causes the temperatures to differ between the bridges. Thus, geographic change in microclimate alters the strength of competition, and determines the geographic limit.&amp;amp;amp;amp;quot;When we travel from south to north, or from a damp region to a dry, we invariably see some species gradually getting rarer and rarer, and finally disappearing; and the change in climate being conspicuous, we are tempted to attribute the whole effect to its direct action. But this is a very false view: we forget that each species, even where it most abounds, is constantly suffering enormous destruction at some period of its life, from enemies or from competitors for the same place and food; and if these enemies or competitors be in the least degree favoured by any slight change of climate, they will increase in numbers, and as each area is already fully stocked with inhabitants, the other species will decrease.&amp;amp;amp;amp;quot;-Charles Darwin, On the Origin of Species, 1859, p. 69.
Phenotypic plasticity of relative investment in shell, eggs, and somatic tissue was examined with... more Phenotypic plasticity of relative investment in shell, eggs, and somatic tissue was examined with experimental population density manipulations in field populations of the intertidal barnacles Semibalanus (Balanus) balanoides from Massachusetts and Balanus glandula and Chthamalus dalli from Washington State, U.S.A. Individuals of S. balanoides of comparable somatic tissue weights produced larger clutches of eggs when crowded and columnar than when conical and uncrowded. Individuals of C. dalli showed a similar pattern. Individuals of B. glandula showed the opposite pattern: at comparable somatic tissue weights, conical uncrowded individuals made slightly larger clutches of eggs than did crowded, columnar individuals. In all cases the greatest shell investment per unit somatic tissue weight was associated with the greatest clutch investment per unit somatic tissue weight.
NOAH LSM Mussel v2.0 is a mathematical model that predicts mussel bed temperatures from atmospher... more NOAH LSM Mussel v2.0 is a mathematical model that predicts mussel bed temperatures from atmospheric and oceanic data by mimicking the thermal properties of a mussel bed exposed to tidal inundation and wave run-up. The model is derived from the National Weather Service NOAH Land Surface Model. In v2.0, it is possible to change the within mussel bed contact which determines conductive heat transfer. Mussel survival is predicted using mussel bed temperatures from the model. Please cite the following papers if you use this code: <strong>NOAH LSM Mussel v2.0</strong> Mislan, KAS and DS Wethey. 2015. A biophysical basis for patchy mortality during heat waves. Ecology. 96:902-907 http://dx.doi.org/10.1890/14-1219.1 <strong>NOAH_LSM_Mussel_v1.0</strong> Wethey DS, LD Brin, B Helmuth, and KAS Mislan. 2011. Predicting intertidal organism temperatures with modified land surface models. Ecological Modelling 222:3568-3576. http://dx.doi.org/10.1016/j.ecolmodel.2011.08.019 <strong>NOAH_LSM</strong> Chen F, and J Dudhia. 2001. Coupling an advanced land surface-hydrology model with the Penn State-NCAR MM5 modeling system. Part I: Model implementation and sensitivity. Monthly Weather Review, 129:569-585. Ek MB, Mitchell KE, Lin Y, Rogers E, Grunmann P, Koren V, and JD Tarpley. 2003. Implementation of Noah land surface model advances in the National Centers for Environmental Prediction operational mesoscale Eta model. Journal of Geophysical Research: Atmospheres (1984–2012), 108(D22). http://dx.doi.org/10.1029/2002JD003296
According to the selfish herd hypothesis, animals can decrease predation risk by moving toward on... more According to the selfish herd hypothesis, animals can decrease predation risk by moving toward one another if the predator can appear anywhere and will attack the nearest target. Previous studies have shown that aggregations can form using simple movement rules designed to decrease each animal&#39;s Domain of Danger. However, if the predator attacks from outside the group&#39;s perimeter, these simple movement rules might not lead to aggregation. To test whether simple selfish movement rules would decrease predation risk for those situations when the predator attacks from outside the flock perimeter, we constructed a computer model that allowed flocks of 75 simulated fiddler crabs to react to one another, and to a predator attacking from 7 m away. We attacked simulated crab flocks with predators of different sizes and attack speeds, and computed relative predation risk after 120 time steps. Final trajectories showed flight toward the center of the flock, but curving away from the predator. Path curvature depended on the predator&#39;s size and approach speed. The average crab experienced a greater decrease in predation risk when the predator was small or slow moving. Regardless of the predator&#39;s size and speed, however, predation risk always decreased as long as crabs took their flock-mates into account. We conclude that, even when flight away from an external predator occurs, the selfish avoidance of danger can lead to aggregation.
Geographic limits of species are commonly associated with climatic or physical boundaries, but th... more Geographic limits of species are commonly associated with climatic or physical boundaries, but the mechanisms of exclusion at the limits of distribution are poorly understood. In some intertidal populations, the strengths of interactions with natural enemies are mediated by microclimate, and determine geographic limits. The northern limit of the barnacle Chthamalus fragilis in New England is the south side of Cape Cod, Massachusetts. South of the cape, Chthamalus has a refuge from competition in the high intertidal, which is too hot for survival of its superior competitor Semibalanus balanoides. North of the cape, the high intertidal is cooler, and Semibalanus survives, so Chthamalus has no refuge. Thus, geographic variation in the strength of competition may determine the geographic limit of Chthamalus. Intolerance of cold by Chthamalus cannot account for the geographic limit: transplants of Chthamalus 80 km beyond its northern limit survived up to 8 yr in the absence of competition with Semibalanus. At the geographic limit of Chthamalus in the Cape Cod Canal there are two bridges, 5 km apart. On the southern bridge, Chthamalus is abundant and occupies a refuge above Semibalanus. On the northern bridge in 2001, only 7 individual Chthamalus were present. Despite the proximity of the bridges, their microclimates are very different. The southern bridge, where Chthamalus is abundant, is up to 8°C hotter than the northern bridge. This higher temperature creates a refuge in the high intertidal for Chthamalus. On the cooler northern bridge, there is no refuge for Chthamalus. Because of the difference in temperatures of the water masses that meet in the canal, heat storage in the rock of the bridge piers causes the temperatures to differ between the bridges. Thus, geographic change in microclimate alters the strength of competition, and determines the geographic limit.&amp;amp;amp;amp;quot;When we travel from south to north, or from a damp region to a dry, we invariably see some species gradually getting rarer and rarer, and finally disappearing; and the change in climate being conspicuous, we are tempted to attribute the whole effect to its direct action. But this is a very false view: we forget that each species, even where it most abounds, is constantly suffering enormous destruction at some period of its life, from enemies or from competitors for the same place and food; and if these enemies or competitors be in the least degree favoured by any slight change of climate, they will increase in numbers, and as each area is already fully stocked with inhabitants, the other species will decrease.&amp;amp;amp;amp;quot;-Charles Darwin, On the Origin of Species, 1859, p. 69.
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