Combining herbarium databases and genetic methods to evaluate the invasion of a popular horticultural species, baby’s breath (Gypsophila paniculata), in the United States

Gypsophila paniculata (baby’s breath) is a popular garden ornamental and horticultural crop introduced to North America in the late 1800s. After introduction it quickly spread, often forming dense monotypic stands and crowding out native species. To better understand this invasion, samples of G. paniculata from seven distinct populations spanning a portion of the plant’s invaded range within the United States (Washington, North Dakota, Minnesota, and Michigan) were collected and genotyped using 14 microsatellite loci. Population structure was inferred using both Bayesian and multivariate methods. The results suggest the presence of at least two genetic clusters among the seven sampling locations, with samples from Washington, North Dakota, Minnesota, and northwestern Michigan forming one genetic cluster and the second cluster consisting of two more southern sampling locations in Michigan. Public herbarium records were used to examine the invasion status (expansion vs. plateau phase) of the identified genetic clusters for G. paniculata . Invasion curves were created from a database of 351 herbarium collections dating from the late 1800s to current day. Results showed that time periods of invasion differed between the two genetics clusters, suggesting at least two invasion events. Patterns of reduced genetic diversity within the earlier invasion could reflect limited standing genetic variation during the initial period of this horticultural species’ import. This study emphasizes how anthropogenic influences can shape the study of invasive plant ecology, particularly when considering species popular in the botanical or horticultural industries.