The described modeling framework has allowed us to identify a broad parameter space where combined systems can in some circumstances outperform single systems in terms of (i) optimizing release thresholds (ii) increasing the speed of population transformation and (iii) enhancing the geographic stability of population transformation.
That is no more than one would expect, given the speed of population growth there.
Determining the speed of population spread in fragmented/heterogeneous landscapes is therefore of utmost importance to ecologists.
The UN's reason for naming a symbolic date as seven-billion day is to draw attention to the speed of population growth, with less than 13 years having passed between the six-billion and seven-billion milestones.
The proposed adaptive strategies on operator selection and parameter settings are aimed at improving both of the convergence speed and population diversity, which are validated by our numerous experiments.
To better settle this problem, a novel double-module immune algorithm named DMMO is presented, where two evolutionary modules are embedded to simultaneously improve the convergence speed and population diversity.
These benefits were shown to speed up population increase by 2 or 12 fold when the host plants were infected with TbCSV or TYLCCNV, respectively (Figure 1).
If all worms do not move at the exact same speed, the population will spread on the gel, creating a phenotypical gradient from slow to fast worms (Fig. 4a).
Accordingly, these experiments did not reveal a linear relation between adaptation speed and population size, but instead a much weaker dependence indicative of a mechanism of "diminishing returns" (De Visser et al. 1999; Shaver et al. 2002).
This result comes from the Allee effect [and the solution to the PDE (1)] by forcing a 'pushed' travelling wave front (Lewis and Kareiva 1993), where the wave speed causes population expansion, contraction, or propagation failure (i.e., pinning; Keitt et al. 2001).
