2.b.iv. Northern-to-Southern Comparisons
Only a few decades have passed since the northern dwelling I. dammini was assigned as a junior synonym of southern dwelling I. scapularis (Oliver et al., 1993). Since then, I. scapularis has been divided into clades to assist in defining the genetic and phenotypic differences among populations (Goddard et al., 2015; Norris et al., 1996; Sakamoto et al., 2014). In the population-level DAPC, the genetic diversity of southern and northern populations is apparent, as northern populations form one large cluster whereas the southern populations are distinct. This is further confirmed by the LEA-based DAPC analysis, in which sample metadata was not input, and each tick was assigned membership probabilities across five clusters which assorted into five major regions (Northeast, Upper Midwest, Central, Southern, and Florida/Southeastern coast). This created three clusters of southern ticks that do not overlap, and two overlapping clusters of northern ticks. The breakdown of these clusters is like the subdivisions found through the microsatellite analysis in Ludwig (2015) and can still be differentiated as broader Northern and Southern groups. The genetic and phenotypic differences found among the two groups, and even the five clusters, warrant further research into genetically defining I. scapularis populations to better understand how these clades impact vectorial capacity across the geographic range of I. scapularis . We were able to identify genomic sites that are correlated to genetic differentiation of northern and southern populations and have found regions of the chromosome-scale scaffolds that are highly variable. Both of which can be used as targets for further phenotypic-focused studies.