Fixation of Neutral Alleles in Spatially Structured Populations via Genetic Drift: Describing the spatial structure of faster-than-panmictic configurations

This paper considers spatially-structured populations described as a network, and examines the properties of these networks in terms of their affect on fixation of neutral alleles due solely to genetic drift. Individuals are modelled as two allele, one locus haploid, diploid and tetraploid structures. The time to fixation for a variety of network configurations is discovered through simulation. The concept of hyperfixation is introduced, which refers to when time to fixation for a network of n nodes occurs more rapidly than the corresponding panmictic n node structure. A hyperfixation index, h, is developed that attempts to characterise a spatial arrangement such that when h < 1 hyperfixation will occur. Issues regarding fixation with ploidy independence, and possible improvements to the described hyperfixation index are discussed.