Phenotypic plasticity of introduced versus native purple loosestrife: univariate and multivariate reaction norm approaches

Abstract

The plastic responses to environmental change by Lythrum salicaria (purple loosestrife) were compared between native plants derived from seeds collected in Europe and those introduced into North America. Plants from nine populations each were grown under two levels of water and nutrient conditions. At the end of the growing season, samples were evaluated for eight traits related to their life history, plant size/architecture, and reproduction. Genetic (G), environmental (E), and G 9 E interactions were assessed by restricted maximum likelihood (REML) analysis of covariance (ANCOVA) and multivariate analysis of covariance (MANCOVA). Both univariate and multivariate reaction norm analyses were used to test for differences in the magnitude and direction of phenotypic plasticity between introduced and native plants. Under high-nutrient conditions, introduced plants were taller and had more branches and greater aboveground biomass. They also exhibited significantly greater amounts of phenotypic plasticity for aboveground biomass than did the natives in response to changing nutrient levels in standing water. This difference in univariate plasticity contributed to the general contrast in multivariate plasticity between introduced and native plants. These results support the idea that introduced plants may successfully invade a habitat and grow better than native plants in response to increased resources.

Biogeography of a plant invasion: genetic variation and plasticity in latitudinal clines for traits related to herbivory

“…Phenotypic plasticity is thought to be beneficial to founding populations by increasing niche breadth (e.g., Richards et al. , Chun , Davidson et al. ) or plasticity may be a trait that evolves in response to the novel environments (Richards et al.…”

“…Phenotypic plasticity is thought to be beneficial to invaders because plastic “general‐purpose genotypes” could have a fitness advantage in founder populations (e.g., Richards et al. , Chun , Davidson et al. ).…”

“…Phenotypic plasticity, variability in the expression of traits in different environments, is another possible mechanism that can generate spatial heterogeneity in native-invasive plant responses to herbivores. Phenotypic plasticity is thought to be beneficial to invaders because plastic "general-purpose genotypes" could have a fitness advantage in founder populations (e.g., Richards et al 2006, Chun 2011, Davidson et al 2011. Alternatively, plasticity may also evolve in an invasive species in response to the novel environment after colonization (Richards et al 2006, Lavergne andMolofsky 2007).…”

Variation in phenotypic plasticity for native and invasive populations of Bromus tectorum

“…By looking across both native and invasive ranges, some studies have demonstrated greater plasticity in invasive versus native populations for invaders such as Lythrum salicaria (Chun et al 2007;Chun 2011), Phalaris arundinacea (Lavergne and Molofsky 2007), and Senecio pterophorus (Cano et al 2008). However, other comparisons have not found strong differences in the plastic responses of native and invasive populations (Maron et al 2007;Bossdorf et al 2005;Andonian and Hierro 2011).…”

When an invasive plant fails to invade

“…In addition, phenotypic plasticity may arise in response to new selection pressures (eg extreme drought events) in a particular range of introductions (Hierro et al . 2005; Chun 2011). Under intense conditions, the individual musk thistle was exhibiting phenotypic plasticity, but its failure to flower and set seed likely meant it had not acquired the proper traits to successfully reproduce.…”