The global issue of biological invasion has become a main threat to biodiversity, and many invasive plant species are causing large-scale damage because of their distribution as garden ornamentals. Baby’s breath (Gypsophila paniculata) is an invasive, herbaceous perennial that forms monotypic stands in the perched dunes along Lake Michigan. It is capable of growing a 4-meter long taproot, and producing 14,000 seeds annually, effectively outcompeting and crowding out federally threatened and endemic species. The goal of this project is to examine the population structure and dispersal patterns of baby’s breath in the northwest Michigan dune system, so as to better understand how this invasion is spreading throughout the region. In the summer of 2016, leaf tissue samples were collected from 945 individuals from four distinct areas along the eastern Lake Michigan shore: 1) Arcadia Dunes, 2) Zetterberg Preserve, 3) Sleeping Bear Dunes National Lakeshore, and 4) Petoskey State Park. The genetic structure and patterns of pollination and seed dispersal were assessed using a combination of baby’s breath-specific microsatellites and universal chloroplast microsatellite markers. This study is the first to analyze the genetic structure of invasive baby’s breath populations in North America to date.
Our results demonstrated a high degree of genetic structure between southern and northern populations of baby’s breath (FST value = 0.33, p-value < 0.0001). In the southern population at Zetterberg Preserve, which anecdotally is considered the origin of the infestation in northwest Michigan, individuals demonstrated higher levels of genetic diversity relative to the northern site, Petoskey State Park. Effective number of alleles in the Zetterberg population was higher (NE = 2.97) than that of the Petoskey population (NE = 2.12). In addition, the population at Zetterberg Preserve exhibited a higher observed heterozygosity (HO = 0.721) compared to the Petoskey population (HO= 0.402). Current analyses are continuing to assess how genetic variation changes across this north-south gradient. We are also examining whether these differences are suggestive of a reduction in genetic diversity as this species spreads north (i.e. through founder effects), or if separate colonization events better describe the genetic variation observed. These results will be used to inform The Nature Conservancy, the National Park Service, and other resource professionals of baby’s breath populations with a high potential to contribute to future invasions, potentially leading to a more targeted management approach.