Fig. 2
From: The effects of sample size on population genomic analyses – implications for the tests of neutrality
The magnitude of selection pressure and the extent of bias in estimating θ. a Relationship between sample size and θ estimates using the nonsynonymous sites (θ N ) of genes under different magnitude of selection. The ratio of nonsynonymous to synonymous substitutions (dN/dS) was used as a proxy for selection intensity on genes. All relationships were significant (P < 0.01). b Correlation between the extent of purifying selection (dN/dS) and the ratio of θ N estimated using small (N = 16) and large (N = 512) sample sizes. The relationship was statistically significant (P < 0.01)