A global synthesis of the patterns of genetic diversity in endangered and invasive plants

Genetic diversity (GD) in populations is important in determining the adaptive potential of populations and is thus thought to influence whether populations decrease or increase in abundance. Yet, a robust evaluation of this premise is needed. By integrating data of 1636 observations from 589 studies globally, we evaluated the relative GD (measured as log response ratio of expected heterozygosity, lnRR) of endangered and invasive plant species compared to control (common or native) species. We also evaluated the variables that influence the variation in population GD within each plant group. Results suggest that the decline in GD is lagging behind the population decline of most endangered plants and that a lower GD did not limit the population expansion of most invasive plants. The effect of inbreeding and gene flow on the relative GD of invasive species was mediated by population size, whereas gene flow directly but nonlinear impacted that of endangered plants, and inbreeding influenced it through an indirect pattern. Mating system was the most important life-history and ecological characteristic to drive relative GD of both endangered plants and invasive plants. The relative GD of endangered plants was also influenced by life form, distribution and rarity form. Overall, genetic diversity was not found to determine species status (endangered or invasive), but species characteristics and genetic factors do have a clear influence on species' evolutionary potential. Understanding the factors that influence GD is key to prioritize management actions on endangered and invasive plants with low and high GD, respectively.