Genetic structure of invasive baby’s breath (Gypsophila paniculata) populations in a freshwater Michigan dune system

ABSTRACT Coastal sand dunes are dynamic ecosystems with elevated levels of disturbance, and as such they are highly susceptible to plant invasions. One such invasion that is of major concern to the Great Lakes dune systems is that of perennial baby’s breath ( Gypsophila paniculata ). The invasion of baby’s breath negatively impacts native species such as the federal threatened Pitcher’s thistle ( Cirsium pitcheri ) that occupy the open sand habitat of the Michigan dune system. Our research goals were to (1) quantify the genetic diversity of invasive baby’s breath populations in the Michigan dune system, and (2) estimate the genetic structure of these invasive populations. We analyzed 12 populations at 14 nuclear and 2 chloroplast microsatellite loci. We found strong genetic structure among populations of baby’s breath sampled along Michigan’s dunes (global F ST = 0.228), and also among two geographic regions that are separated by the Leelanau peninsula. Pairwise comparisons using the nSSR data among all 12 populations yielded significant F ST values. Results from a Bayesian clustering analysis suggest two main population clusters. Isolation by distance was found over all 12 populations (R = 0.755, P < 0.001) and when only cluster 2 populations were included (R = 0.523, P = 0.030); populations within cluster 1 revealed no significant relationship (R = 0.205, P = 0.494). Private nSSR alleles and cpSSR haplotypes within each cluster suggest the possibility of at least two separate introduction events to Michigan.