Fig. 4

Within-region population genetic diversity varies across space and time. Points represent the average pairwise distance (using the Kimura 2-parameter model) between ticks within each of the five regions of New York in each of three collection years. Vertical lines around each point represent ± 95% confidence intervals and lines connect points from the same region across sampling years. The year 2004 was excluded because ticks were sampled only in the Hudson River Valley that year. Points are jittered on the X-axis for clarity. In 2008, the first year in which ticks were collected from all regions, the population genetic diversity did not differ among regions. Within-region diversity was generally high in the Hudson River Valley in subsequent years, and clearly higher than other regions among ticks collected in 2013. While it is clear that within-region diversity was lowest in the North region in the most recent sampling year, that pattern was inconsistent in previous years. Among all regions except for the North region, there was clear support for genetic diversity within regions increasing over time