4.10. Changes in the population size

In the eastern lineage of the grey partridge the observed distribution of pairwise genetic distances followed that of an expected distribution under population expansion (VI, Fig. 3). This model was also supported by the star-like minimum-spanning network (VI, Fig. 2), with one basic and several closely related haplotypes. Also Tajima’s D, which in addition to assessing neutrality of the used marker reflects demographic changes in the past in relation to the population size (Tajima 1989), was significantly negative. On the other hand, the significantly positive D found in Finland (FI1) may express the finding of both lineages in this population (VI).

The western lineage did not follow the models for either expansion or equilibrium (VI, Fig. 3). However, the minimum-spanning network of the western lineage was star-like as in the eastern lineage, and Tajima’s D was significantly negative. The significantly negative D found in England (EN2) may have resulted from a past population bottleneck and expansion (VI, Table 4).