Phenotypic plasticity in vegetative and reproductive traits in an invasive weed, Lythrum salicaria (Lythraceae), in response to soil moisture

Abstract

In colonizing species, high phenotypic plasticity can contribute to survival and propagation in heterogenous adventive environments, and it has been suggested as a predictor of invasiveness. Observation of natural populations of an invasive species, Lythrum salicaria salicaria, indicated extensive variation in its growth and reproductive traits. Phenotypic plasticity of different life history traits of L. salicaria was investigated using vegetative clones of each of 12 genotypes from one population in Ontario, Canada. We chose soil moisture as the treatment factor because of its importance in wetland species and raised all 12 genotypes in each of four soil moisture treatments. We examined an array of vegetative and reproductive traits, including root and shoot mass, shoot and inflorescence length, total seed set, floral mass, and morphometric variables. All observed vegetative as well as reproductive traits demonstrated significant phenotypic plasticity in response to soil moisture treatment. Even the stigma-anther separation involved significant genotype by environment interactions, suggesting that soil moisture may modify the relative positions of anthers and stigma. Compared to vegetative traits, most reproductive traits demonstrated crossing reaction norms, implying that the average differences in those traits among genotypes vary with the environment maintaining the genetic variation in a population.

Effects of admixture in native and invasive populations of Lythrum salicaria

“…This result is consistent with observations in other species (Davidson et al 2011). A previous study also showed that invasive L. salicaria has phenotypic plasticity in both vegetative and reproductive traits (Mal and Lovett-Doust 2005). At high nutrient levels (as in our study), both shoot and root biomass exhibited greater phenotypic plasticity to increased water levels in invasive L. salicaria compared to native genotypes (Chun et al 2007).…”

“…The bigger size of invasive L. salicaria is consistent with previous observations in this species (Blossey and Notzold 1995;Bastlova and Kvet 2002;Mal and Lovett-Doust 2005;Chun et al 2009;Joshi and Tielborger 2012;Joshi et al 2014) and for invasive species in general (Gallagher et al 2015). Several non-exclusive hypotheses can explain this pattern.…”

Do Plants Have a Choice of Traits to Be Modulated? Evidence from an Invasive Plant <i>Mikania micrantha</i> Kunth in Different Urban Environments

“…In spite of producing self-incompatible flowers, M. micrantha has been found to be an extremely successful colonizer [40], and appears to be an exception to the Baker's law [41]. The plasticity in mating systems has been found to increase the long-distance colonizing ability of an invasive species, and assuring reproduction at low population densities [42] which could be crucial for invaders to colonize urban areas. In view of increasing urbanization, which is now considered a major driving force of plant biodiversity loss and community homogenization [43], integrated studies involving both vegetative and reproductive traits that affect the ability of a population to tolerate environmental heterogeneity [44], are necessary for understanding the plasticity patterns in M. micrantha.…”

Extreme Climatic Events as Drivers of Ecosystem Change

“…Leiocarpa density depended almost solely on high drought survivorship, and the final composition of the vegetation found in the more xeric habitats primarily reflected the drought hardy nature of this species. The presence of such complex patterns is perhaps not surprising given the diversity of strategies displayed by plants for ensuring survival through drought and other abiotic stresses (e.g., Barrett 1998;Mal & Lovett-Doust 2005;McDowell et al 2008) but it does indicate that post-drought community composition jointly reflects the processes of mortality and recovery in heterogeneous environments.…”