Genetic Structure of Invasive Baby's Breath (Gypsophila paniculata L.) Populations in a Michigan Dune System

Abstract

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 F_ST = 0.228), and pairwise comparisons among all populations yielded significant F_ST 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.

Keywords: coastal sand dunes; genetic diversity; invasive species; landscape genetics; population structure.

Figure 1

Map of Gypsophila paniculata sampling locations in Michigan. Seven were located throughout Sleeping Bear Dunes National Lakeshore. The park boundary is delineated by grey shading in bottom left panel. Sampling location codes: Grand Marais (GM), Petoskey State Park (PS), Traverse City (TC), Good Harbor Bay (GHB), Sleeping Bear Point (SBP), Dune Climb (DC), Dune Plateau (DP), Empire Bluffs (EB), Platte Bay (PB), South Boundary (SB), Zetterberg Preserve (ZP), Arcadia Dunes (AD).

Figure 2

Identification of K clusters for G. paniculata in the MI dunes system. (A) Results from Bayesian cluster analysis based on nSSR data using the program STRUCTURE indicate (K = 2) population clusters. Cluster 1 (left, orange) includes the primarily northeast populations, and Cluster 2 (right, purple) includes all other populations, (B) Scatterplot of both discriminant function axes from the discriminant analysis of principal components (DAPC), (C) DAPC sample distribution on discriminant function 1, (D) Table of individual membership to each DAPC cluster, explained by the PCA eigenvalues used in the DAPC, based on all 69 identified principal components. Sampling location codes: Grand Marais (GM), Petoskey State Park (PS), Traverse City (TC), Good Harbor Bay (GHB), Sleeping Bear Point (SBP), Dune Climb (DC), Dune Plateau (DP), Empire Bluffs (EB), Platte Bay (PB), South Boundary (SB), Zetterberg Preserve (ZP), Arcadia Dunes (AD).

Figure 3

Genetic connectivity map for both (A) land cover and (B) digital elevation model-based (DEM) optimized resistance surfaces for populations belonging to cluster 2, southwest of the Leelanau Peninsula. Aerial view of the digitized portion is outlined in (C). White circles indicate sampling locations, and from north to south, they include Good Harbor Bay (GHB), Sleeping Bear Point (SBP), Dune Climb (DC), Dune Plateau (DP), Empire Bluffs (EB), Platte Bay (PB), South Boundary (SB), Zetterberg Preserve (ZP), and Arcadia Dunes (AD). The color indicates a current gradient, with dark purple indicating low current (high resistance) and yellow indicating high current (low resistance).