Table 1. Symbols used in the text.

Ne	Effective population size
S	Number of diploid individuals in a sample
n11	Number of genotypes in a sample with aa at first locus and bb at second locus
n12	Number of aa b– genotypes where – refers to non-b allele at the second locus
n21	Number of a– bb genotypes
n22	Number of a– b– genotypes
na, nb	Number of a and b alleles respectively
pa, pb	Allele frequencies in gametic and composite table, = na/2S and nb/2S
pab	Frequency of the ab haplotype
D	Gametic disequilibrium coefficient = pab – papb
r2	Gametic correlation = D2/[pa(1– pa)pb(1– pb)]
M	Number of ab haplotypes in composite haplotype table = 4n11+2n12+2n21+ n22
pab(comp)	Frequency of ab in composite haplotype table = M/4S
D(comp)	Disequilibrium coefficient from composite haplotype table = pab(comp) – papb
Δ	Burrows’ disequilibrium coefficient = 2D(comp)
r2(comp)	r2 value from composite haplotype table = D2(comp)/[pa(1– pa)pb(1– pb)]
	Composite r2 parameter = 4r2(comp)
	Estimate of from sample
	with single-locus disequilibrium =
?2(comp)	?2 calculated from composite haplotype table
pn	Frequency of null alleles at a locus
α	Half the difference between coupling and repulsion heterozygote frequencies