Table 1. Expected and observed Duffy-null allele frequencies for each island and source population.

Expected Duffy-null frequencies are approximated by mean West African global ancestry proportion for each island, calculated using the admixture software.

Population	n (sampled individuals)	Expected frequency	Observed frequency	Binomial test p-value
Santiago	172	0.737	0.834	2.193 ×10−5
Fogo	129	0.498	0.539	0.192
NW Cluster	236	0.552	0.557	0.817
GWD	107	0.997	1.000	-
IBS	107	0.002	0.019	-