Fig. 5From: Phylogeographic dynamics of the arthropod vector, the blacklegged tick (Ixodes scapularis)The observed frequency distribution of pairwise differences among haplotypes (solid line) of Ixodes scapularisdiffers from that expected in populations that are not expanding (dashed line). Unimodal frequency distributions are most commonly interpreted as indications of increasing population sizesBack to article page