POPULATION STRUCTURE

Consider several subpopulations of the same species separated geographically.

In the absence of selection and with random mating, two trends are expected:

gene frequencies for the total population are expected to remain constant over generations;
the variance of gene frequencies is expected to increase over time because of differentiation among subpopulations.

Wright's F statistics (Wright, 1965), quantify the differentiation among subpopulations and among individuals.

Cockerham (1973) showed how F statistics could be estimated from an analysis of variance comparing mean gene frequencies.

F statistics apply to two possible alleles at a particular locus.

Long (1986) extended Cockerham's analysis to several loci each having two or more possible alleles. This method was particularly suited to the analysis of allozyme data.

POPULATION STRUCTURE

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