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Genetics. 2007 Sep;177(1):435-48. Epub 2007 Jul 29.

The population genetic structure of clonal organisms generated by exponentially bounded and fat-tailed dispersal.

Author information

  • 1Department of Disease and Stress Biology, John Innes Centre, Norwich NR4 7UH, United Kingdom. luzie.wingen@bbsrc.ac.uk

Abstract

Long-distance dispersal (LDD) plays an important role in many population processes like colonization, range expansion, and epidemics. LDD of small particles like fungal spores is often a result of turbulent wind dispersal and is best described by functions with power-law behavior in the tails ("fat tailed"). The influence of fat-tailed LDD on population genetic structure is reported in this article. In computer simulations, the population structure generated by power-law dispersal with exponents in the range of -2 to -1, in distinct contrast to that generated by exponential dispersal, has a fractal structure. As the power-law exponent becomes smaller, the distribution of individual genotypes becomes more self-similar at different scales. Common statistics like GST are not well suited to summarizing differences between the population genetic structures. Instead, fractal and self-similarity statistics demonstrated differences in structure arising from fat-tailed and exponential dispersal. When dispersal is fat tailed, a log-log plot of the Simpson index against distance between subpopulations has an approximately constant gradient over a large range of spatial scales. The fractal dimension D2 is linearly inversely related to the power-law exponent, with a slope of approximately -2. In a large simulation arena, fat-tailed LDD allows colonization of the entire space by all genotypes whereas exponentially bounded dispersal eventually confines all descendants of a single clonal lineage to a relatively small area.

PMID:
17660543
[PubMed - indexed for MEDLINE]
PMCID:
PMC2013728
Free PMC Article

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