Future directions
Understanding how plant population genetic structure is affected by life history traits can greatly improve management strategies for populations facing increasingly fragmented habitats due to human-accelerated global change. Our study reveals that gene flow is generally more limited in non-woody species pollinated by small insects, making them more susceptible to isolation and loss of genetic diversity. Thus, in order to preserve the largest amount of genetic diversity for species with such traits, conservation efforts should seek to maintain numerous subpopulations spanning a wide geographic extent. Future broad-scale studies of FST variation could provide more even greater insights for conservation by including population densities (Murawski & Hamrick, 1991; Sork et al., 1999), effects of habitat fragmentation (Aguilar, Quesada, Ashworth, Herrerias-Diego, & Lobo, 2008; Skogen et al., 2019), and the landscape context of populations (Sork et al., 1999).
Another avenue for future research involves linking patterns of genetic variation at different scales. Little is known about how factors that affect genetic patterns over fine spatial scales (i.e., within subpopulations) extend to genetic patterns over larger spatial scales (i.e., among subpopulations). Intuitively, species with greater fine-scale genetic structure (Loiselle, Sork, Nason, & Graham, 1995) should also have greater population genetic structure, but this has rarely been tested. For example, a recent review found greater fine-scale genetic structure in species with short-distance dispersers, than those dispersed by birds (Gelmi‐Candusso et al., 2017), but it is unclear whether this difference would extend over larger distances. Overall, we expect that more comprehensive studies of ecological interactions, in combination with increasing amounts of genetic data collected at various spatial scales will continue to improve our understanding of the factors that influence population genetic structure in seed plants.