CHRYSANTHEMUM PRODUCTION PLANNING UNDER TIME-TO-HARVEST UNCERTAINTY

Crop Production/Industries,

Trophicâ specific responses to migration in empirical metacommunities

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154529/1/oik12963.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154529/2/oik12963_am.pd

Evolution of cooperation in multilevel public goods games with community structures

In a community-structured population, public goods games (PGG) occur both within and between communities. Such type of PGG is referred as multilevel public goods games (MPGG). We propose a minimalist evolutionary model of the MPGG and analytically study the evolution of cooperation. We demonstrate that in the case of sufficiently large community size and community number, if the imitation strength within community is weak, i.e., an individual imitates another one in the same community almost randomly, cooperation as well as punishment are more abundant than defection in the long run; if the imitation strength between communities is strong, i.e., the more successful strategy in two individuals from distinct communities is always imitated, cooperation and punishment are also more abundant. However, when both of the two imitation intensities are strong, defection becomes the most abundant strategy in the population. Our model provides insight into the investigation of the large-scale cooperation in public social dilemma among contemporary communities.Comment: 6 pages, 4 figures, Accepted by EP

Models for regional heartwater epidemiology in a variable environment

A model of the epidemic dynamics of heartwater within a cattle production unit was presented by Yonow et al. (1998). Here, the model is expanded to a region consisting of several farms to study the effect of environmental variability on control strategies. We have shown that: • In a region, where the environment of each farm is modelled with constant epidemiologic parameter values, while the between-farm parameter values differ, regional variation in the removal rate of infected cattle increases the average fraction of infected cattle across the region , while regional variation in the transmission rate of infection from ticks to cattle decreases the average fraction of infected cattle, thereby requiring control measures that keep the removal rate uniform and the transmission rate variable. • In a region, where in addition to regional variation between farms, the epidemiologic parameters of each farm are time-variant, then temporal variation in both the transmission rate and removal rate increases the average fraction of infected cattle across the region, thereby requiring control measures that keep both parameters uniform.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat v.9 was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.mn201

Probability and Social Science. Methodological Relationships between the Two Approaches

No abstract available

Minimizing the population extinction risk by migration

Many populations in nature are fragmented: they consist of local populations occupying separate patches. A local population is prone to extinction due to the shot noise of birth and death processes. A migrating population from another patch can dramatically delay the extinction. What is the optimal migration rate that minimizes the extinction risk of the whole population? Here we answer this question for a connected network of model habitat patches with different carrying capacities.Comment: 7 pages, 3 figures, accepted for publication in PRL, appendix contains supplementary materia

Replicators in Fine-grained Environment: Adaptation and Polymorphism

Selection in a time-periodic environment is modeled via the two-player replicator dynamics. For sufficiently fast environmental changes, this is reduced to a multi-player replicator dynamics in a constant environment. The two-player terms correspond to the time-averaged payoffs, while the three and four-player terms arise from the adaptation of the morphs to their varying environment. Such multi-player (adaptive) terms can induce a stable polymorphism. The establishment of the polymorphism in partnership games [genetic selection] is accompanied by decreasing mean fitness of the population.Comment: 4 pages, 2 figure

The evolution of dispersal in a Levins’ type metapopulation model

We study the evolution of the dispersal rate in a metapopulation model with extinction and colonisation dynamics, akin to the model as originally described by Levins. To do so we extend the metapopulation model with a description of the within patch dynamics. By means of a separation of time scales we analytically derive a fitness expression from first principles for this model. The fitness function can be written as an inclusive fitness equation (Hamilton’s rule). By recasting this equation in a form that emphasizes the effects of competition we show the effect of the local competition and on the local population size on the evolution of dispersal. We find that the evolution of dispersal cannot be easily interpreted in terms of avoidance of kin competition, but rather that increased dispersal reduces the competitive ability. Our model also yields a testable prediction in term of relatedness and life history parameters

Fast migration and emergent population dynamics

We consider population dynamics on a network of patches, each of which has a the same local dynamics, with different population scales (carrying capacities). It is reasonable to assume that if the patches are coupled by very fast migration the whole system will look like an individual patch with a large effective carrying capacity. This is called a "well-mixed" system. We show that, in general, it is not true that the well-mixed system has the same dynamics as each local patch. Different global dynamics can emerge from coupling, and usually must be figured out for each individual case. We give a general condition which must be satisfied for well-mixed systems to have the same dynamics as the constituent patches.Comment: 4 page