This function calculates delta ($\delta$), the differential
between allelic frequencies in two populations. It is called by the
function prepare.data.
Usage
delta(SpA, SpB)
Arguments
SpA
a vector of population allele frequencies.
SpB
a vector of population allele frequencies.
Value
This function returns a vector of length one with the value of $\delta$.
Details
This function calculates the allele frequency differential for a pair of
species or populations ($\delta$, Gregorius and Roberds 1986) for a
single locus.
$$\delta = \sum_{i} \frac{|f_{i1} - f_{i2}|}{2}$$
where $f_{i1}$ and $f_{i2}$ denote the frequency of the
ith allele in populations one and two, respectively.
$\delta$ ranges from 0, for identical populations, to 1, for
populations that share no alleles in common.
References
Gregorius, H. R. and Roberds, J. H. (1986) Measurement of genetical
differentiation among subpopulations. Theoretical and Applied
Genetics, 71, 826-834.