Coastal sand dunes are dynamic ecosystems with elevated levels of disturbance and are highly susceptible to plant invasions. One invasive plant that is of concern to the Great Lakes system is Gypsophila paniculata L. (perennial baby’s breath). The presence of G. paniculata negatively impacts native species and has the potential to alter ecosystem dynamics. Our research goals were to (1) estimate the genetic structure of invasive G. paniculata along the Michigan dune system and (2) identify landscape features that influence gene flow in this area. We analyzed 12 populations at 14 nuclear and two chloroplast microsatellite loci. We found strong genetic structure among populations (global FST = 0.228), and pairwise comparisons among all populations yielded significant FST values. Results from clustering analysis via STRUCTURE and discriminant analysis of principal components (DAPC) suggest two main genetic clusters that are separated by the Leelanau Peninsula, and this is supported by the distribution of chloroplast haplotypes. Land cover and topography better explained pairwise genetic distances than geographic distance alone, suggesting that these factors influence the genetic distribution of populations within the dunes system. Together, these data aid in our understanding of how invasive populations move through the dune landscape, providing valuable information for managing the spread of this species.

29Coastal sand dunes are dynamic ecosystems with elevated levels of disturbance, and as such they 30 are highly susceptible to plant invasions. One such invasion that is of major concern to the Great 31Lakes dune systems is that of perennial baby's breath (Gypsophila paniculata). The invasion of 32 baby's breath negatively impacts native species such as the federal threatened Pitcher's thistle 33 (Cirsium pitcheri) that occupy the open sand habitat of the Michigan dune system. Our research 34 goals were to (1) quantify the genetic diversity of invasive baby's breath populations in the 35Michigan dune system, and (2) estimate the genetic structure of these invasive populations. We 36 analyzed 12 populations at 14 nuclear and 2 chloroplast microsatellite loci. We found strong 37 genetic structure among populations of baby's breath sampled along Michigan's dunes (global 38 F ST = 0.228), and also among two geographic regions that are separated by the Leelanau 39 peninsula. Pairwise comparisons using the nSSR data among all 12 populations yielded 40 significant F ST values. Results from a Bayesian clustering analysis suggest two main population 41 clusters. Isolation by distance was found over all 12 populations (R = 0.755, P < 0.001) and 42 when only cluster 2 populations were included (R = 0.523, P = 0.030); populations within cluster 43 1 revealed no significant relationship (R = 0.205, P = 0.494). Private nSSR alleles and cpSSR 44 haplotypes within each cluster suggest the possibility of at least two separate introduction events 45 to Michigan. 46 47

Premise of the Study Gypsophila paniculata (baby's breath; Caryophyllaceae) is a herbaceous perennial that has invaded much of northern and western United States and Canada, outcompeting and crowding out native and endemic species. Microsatellite primers were developed to analyze the genetic structure of invasive populations.Methods and ResultsWe identified 16 polymorphic nuclear microsatellite loci for G. paniculata out of 73 loci that successfully amplified from a primer library created using Illumina sequencing technology. Microsatellite primers were developed to amplify di‐, tri‐, and tetranucleotide repeats and tested in three invasive populations in Michigan.ConclusionsThese markers will be useful in characterizing the genetic structure of invasive populations throughout North America to aid targeted management efforts, and in native Eurasian populations to better understand invasion history. Five of these developed primers also amplified in G. elegans.

Baby’s breath (Gypsophila paniculata L.) is an invasive species in Michigan’s northern lower peninsula and is a problem in much of northern North America. It is of particular concern in coastal dune habitats of northwest Michigan, because the areas where it is most dense are also populated by several endemic and threatened species. Current removal methods include manual removal with a spade and directed spray-to-wet foliar application of glyphosate to individual plants using backpack sprayers. We assessed these methods by measuring G. paniculata density and presence–absence frequency before and after treatment using a point-intercept grid, establishing how type and timing of treatment within the growing season influences treatment efficacy and determining the proportion of plants that resprout after treatment. Our results show a consistent reduction in G. paniculata density after treatment with herbicide or manual removal (P < 0.001) but minimal impact on presence–absence frequency. These results indicate a need for quantitative data in the assessment of management efficacy to show a clearer picture of density reduction when extirpation is no longer a viable outcome of management. Through the assessment of treatment timing of manual removal and glyphosate treatments over time, we found no evidence that either treatment type was effective at reducing density when applied before plants flowered, but there was evidence that both treatments were effective when applied later in the growing season when plants were flowering. Resprouting of marked plants occurred in 14% of manually removed plants and 2% of herbicide-treated plants. Our results suggest that managers should treat G. paniculata infestations for consecutive years to remove regrowth and focus treatment during flowering for best control.

Premise of the study: Gypsophila paniculata L. (baby’s breath) is an herbaceous perennial that has invaded much of northern and western United States and Canada, outcompeting and crowding out native and endemic species. Microsatellite primers were developed to analyze the genetic structure of invasive populations.Methods and Results: We have identified 16 polymorphic nuclear microsatellite loci for G. paniculata out of 73 loci that successfully amplified from a primer library created using Illumina sequencing technology. The developed primers amplified microsatellite loci in 3 invasive populations in Michigan. Primers amplified di-, tri-, and tetra-nucleotide repeats.Conclusions: These markers will be useful in characterizing the genetic structure of invasive populations throughout North America to aid targeted management efforts, and in native Eurasian populations to better understand invasion history. Five of these developed primers also amplified in G. elegans.