scholarly journals Synchronisation of fertility with carrying capacity; an investigation using classical and agent based modeling

2013 ◽  
Vol 50 ◽  
Author(s):  
Hugh Crozier Murrell ◽  
John Henry Swart
Keyword(s):  
Natural Selection ◽  
Phase Shift ◽  
Carrying Capacity ◽  
Numerical Solutions ◽  
Agent Based Modeling ◽  
Fertility Rate ◽  
Agent Based ◽  
Species Survival ◽  
Selection For ◽  
Model Subject

A generalized Verhulst model subject to seasonal change in both fertility rate and carrying capacity is outlined. Numerical solutions to the Verhulst equations are employed to obtain optimal fertility rate phase shift with respect to carrying capacity. Possible natural selection for a preferred season of conception is investigated using agent based simulations. Both experiments indicate that synchronization of fertility rate to environment carrying capacity is beneficial to species survival.

scholarly journals Evolutionary dynamics of a virus in a vaccinated population

2021 ◽  
Author(s):  
Graham Bell
Keyword(s):  
Natural Selection ◽  
Evolutionary Dynamics ◽  
Vaccine Design ◽  
Dynamic Regime ◽  
Agent Based ◽  
Virus Escape ◽  
Escape Mutants ◽  
Prevalent Strain ◽  
Selection For ◽  
P Locus

The progress of an epidemic in a small closed community is simulated by an agent-based model which allows vaccination and variation. The attributes of the virus are governed by two genetic loci: the P-locus, which determines growth, and the M-locus, which determines immune characteristics. Mutation at either locus modifies the attributes of the virus and leads to evolution through natural selection. For both loci the crucial variable is the potential mutation supply UPot, because evolution is likely to happen when UPot > 1. Mutation at the P-locus causes a limited increase in virulence, which may be affected by vaccine design. Mutation at the M-locus may cause a qualitative shift of dynamic regime from a simple limited epidemic to a perennial endemic disease by giving rise to escape mutants which may themselves mutate. A broad vaccine that remains efficacious despite several mutations at the M-locus prevents this shift and provides protection despite the evolution of the virus. Escape variants may nevertheless arise through recombination after coinfection, and can be suppressed by timely revaccination, using the prevalent strain to design the vaccine.

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