Figure 1.

(a) Map of all sampling sites in NYC and the surrounding region. Colours correspond to the National Land Cover Database: dark red, Urban High Density Development; light red, Urban Medium to Low Density Development; greens, Forested areas; yellow, Grasslands. Squares, sampling sites from MM; circles, sites from LI; yellow shapes, sites used for urban population demographic analysis. (See electronic supplementary material S1, table S1 for full site names). (b) TreeMix population tree. Red arrows represent significant admixture using TreeMix and f3 statistics. The drift parameter is plotted along the x-axis and represents the amount of genetic drift along the branch. Letters = sampling site codes (see electronic supplementary material, table S1 for full names; AP and CN were combined for all other analyses). Letters in bold and coloured branches correspond to urban sampling sites described in (a) and show urban populations with relatively high levels of divergence to non-urban populations, as evidenced by long-branch lengths.