The Implications of Density-Dependent Population Growth for Frequency- and Density-Dependent Selection

1976 ◽  
Vol 110 (975) ◽  
pp. 849-860 ◽  
Author(s):  
Peter E. Smouse
Keyword(s):  
Population Growth ◽  
Density Dependent ◽  
Density Dependent Selection

scholarly journals Density-dependent selection and the limits of relative fitness

2017 ◽  
Author(s):  
Jason Bertram ◽  
Joanna Masel
Keyword(s):  
Population Density ◽  
Population Growth ◽  
Competitive Ability ◽  
Relative Fitness ◽  
Density Dependent ◽  
Volterra Models ◽  
Selection Behavior ◽  
Novel Model ◽  
Stable Populations ◽  
Density Dependent Selection

AbstractSelection is commonly described by assigning constant relative fitness values to genotypes. Yet population density is often regulated by crowding. Relative fitness may then depend on density, and selection can change density when it acts on a density-regulating trait. When strong density-dependent selection acts on a density-regulating trait, selection is no longer describable by density-independent relative fitnesses, even in demographically stable populations. These conditions are met in most previous models of density-dependent selection (e.g. “K-selection” in the logistic and Lotka-Volterra models), suggesting that density-independent relative fitnesses must be replaced with more ecologically explicit absolute fit-nesses unless selection is weak. Here we show that density-independent relative fitnesses can also accurately describe strong density-dependent selection under some conditions. We develop a novel model of density-regulated population growth with three ecologically intuitive traits: fecundity, mortality, and competitive ability. Our model, unlike the logistic or Lotka-Volterra, incorporates a density-dependent juvenile “reproductive excess”, which largely decouples density-dependent selection from the regulation of density. We find that density-independent relative fitnesses accurately describe strong selection acting on any one trait, even fecundity, which is both density-regulating and subject to density-dependent selection. Pleiotropic interactions between these traits recovers the familiarK-selection behavior. In such cases, or when the population is maintained far from demographic equilibrium, our model offers a possible alternative to relative fitness.

Density-Dependent Selection on Polymorphic Prey -- Some Data

1977 ◽  
Vol 111 (979) ◽  
pp. 594-598 ◽  
Author(s):  
Laurence M. Cook ◽  
Patricia Miller
Keyword(s):  
Density Dependent ◽  
Density Dependent Selection

Density-Dependent Population Growth

2020 ◽  
pp. 29-46
Author(s):  
Michael J. Fogarty ◽  
Jeremy S. Collie
Keyword(s):  
Population Density ◽  
Population Growth ◽  
Density Dependence ◽  
Multiple Equilibria ◽  
Dynamical Behavior ◽  
Logistic Growth ◽  
Density Dependent ◽  
Per Capita ◽  
Discrete Time Models ◽  
Complex Dynamical Behavior

The observation that no population can grow indefinitely and that most populations persist on ecological timescales implies that mechanisms of population regulation exist. Feedback mechanisms include competition for limited resources, cannibalism, and predation rates that vary with density. Density dependence occurs when per capita birth or death rates depend on population density. Density dependence is compensatory when the population growth rate decreases with population density and depensatory when it increases. The logistic model incorporates density dependence as a simple linear function. A population exhibiting logistic growth will reach a stable population size. Non-linear density-dependent terms can give rise to multiple equilibria. With discrete time models or time delays in density-dependent regulation, the approach to equilibrium may not be smooth—complex dynamical behavior is possible. Density-dependent feedback processes can compensate, up to a point, for natural and anthropogenic disturbances; beyond this point a population will collapse.

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