Models that involve positive selection driving divergence are unlikely to be able to explain this dependence on population size, since larger populations respond more quickly to a given selection pressure (Gavrilets 2003).
In addition, there are theoretical models that predict no dependence on population size of the population-scaled fitness effects (Cherry 1998; Goldstein 2013), depending on the exact nature of the genotype phenotype map.
On the other hand, the Allee effect, which describes a negative density dependence, the population growth rate is reduced at low population size, has recently being studied by many scholars ([27 31]).
This dependence on population density has the implication that the expected local increase of population density due to increased urbanization [42], especially in Africa [43], will increasingly exacerbate the risk of malaria unless control measures are implemented [39].
By examining the behavior in each of these regimes in turn, we found that the probability of valley-crossing has a complex, non-monotonic dependence on population size, and identified a parameter Γ that reliably predicts the population size at which valley crossing becomes preferred.
Freire et al. (2013) considered the time dependence of population exposure with respect to tsunami threat and developed high-resolution daytime and nighttime population distribution maps.
(b) Sketch of the related time dependence of population (P_{0}(t)) of the ground state (m_{mathrm{s}} = 0).
Research suggests two general explanations for repeat victimization state dependence and population heterogeneity (Lauritsen and Quinet 1995; Osborn and Tseloni 1998; Wittebrood and Nieuwbeerta 2000).
While this argument makes it clear why environmental stochasticity should not be regarded as haveing an explicit dependence on population size, the reasons for suggesting that demographic stochasticity should have such a dependence are not equally compelling.
Total mortality (Z) is set at twice the natural mortality (this condition is applied to minimize the effects of density dependence) and population growth is stable (r = 0) [34].
