Phenotypic Plasticity in the Invasion of Crofton Weed (Eupatorium adenophorum) in China

Abstract

Phenotypic plasticity and rapid evolution are two important strategies by which invasive species adapt to a wide range of environments and consequently are closely associated with plant invasion. To test their importance in invasion success of Crofton weed, we examined the phenotypic response and genetic variation of the weed by conducting a field investigation, common garden experiments, and intersimple sequence repeat (ISSR) marker analysis on 16 populations in China. Molecular markers revealed low genetic variation among and within the sampled populations. There were significant differences in leaf area (LA), specific leaf area (SLA), and seed number (SN) among field populations, and plasticity index (PI v ) for LA, SLA, and SN were 0.62, 0.46 and 0.85, respectively. Regression analyses revealed a significant quadratic effect of latitude of population origin on LA, SLA, and SN based on field data but not on traits in the common garden experiments (greenhouse and open air). Plants from different populations showed similar reaction norms across the two common gardens for functional traits. LA, SLA, aboveground biomass, plant height at harvest, first flowering day, and life span were higher in the greenhouse than in the open-air garden, whereas SN was lower. Growth conditions (greenhouse vs. open air) and the interactions between growth condition and population origin significantly affect plant traits. The combined evidence suggests high phenotypic plasticity but low genetically based variation for functional traits of Crofton weed in the invaded range. Therefore, we suggest that phenotypic plasticity is the primary strategy for Crofton weed as an aggressive invader that can adapt to diverse environments in China. Nomenclature: Crofton weed, Eupatorium adenophorum Spreng EUPAD.

Low genetic diversity contrasts with high phenotypic variability in heptaploid Spartina densiflora populations invading the Pacific coast of North America

“…Many of the studied plant traits had PI v values higher than 50% in the field, and the mean PI v for every trait was 54 ± 4%, within the range recorded for other invasive plant species (Funk, 2008) and native species along wide latitudinal ranges (Chun-Can et al, 2014;Molina-Montenegro & Naya, 2012;Zhao et al, 2012). Our results are also consistent with previous studies on other polyploid…”

“…However, our results show that they were kept at the individual level with some individuals from low latitudes (specially from Humboldt Bay) accumulating more Chl b and Car in the field and in the glasshouse and some individuals from high latitudes (specially from Vancouver Island) showing the opposite response. Thus, although environmental conditions, hybridization, and polyploidy largely determined plant traits in S. densiflora , our results point to a genetic or epigenetic component influencing certain traits due to changing selection pressures along a wide latitudinal range (Zhao et al., ). Ayres et al.…”

“…In this context, few studies have evaluated the relationships between genetic differentiation and phenotypic plasticity of invasive plant species to novel, changing environments along wide latitudinal ranges. These studies have shown that species with low genetic variation can colonize wide latitudinal ranges due to high plasticity levels, sometimes related to polyploidy and hybridization, and their spread into dissimilar environments can lead to genetic differentiation (Counts, ; De Kort et al., ; Meyerson et al., ; Quilot‐Turion et al., ; Zhao, Yang, Xi, Gao, & Sun, ). For example, the high level of epigenetic changes recorded in invasive Spartina anglica (Parisod et al., ; Salmon, Ainouche, & Wendel, ) has been related to its high levels of morphological plasticity and its large ecological amplitude (Thompson, McNeilly, & Gay, ), contrasting with low interindividual genetic diversity (Ainouche, Baumel, & Salmon, ; Ayres & Strong, ; Baumel, Ainouche, & Levasseur, ).…”

A New Strategy for the Prevention and Control of Eupatorium adenophorum under Climate Change in China

“…At present, the weed is spreading north and west to drier, colder, higher regions, and has adapted to lower soil pH [3,10]. Former studies have focused on the factors that influence the spread of E. adenophorum, including environmental factors (e.g., elevation, temperature, precipitation, illumination and soil pH) [3,5,[10][11][12][13], biological factors (e.g., biomass of invaded areas, allelopathy, and competitive relationship) [4,5,7], genetic characteristics (e.g., rapid evolution and phenotypic plasticity) [8,14], and impact of human activities (e.g., land use patterns and road distribution) [3,5,7]. In regard to environmental factors, relatively high light intensity and high temperature in winter can contribute to the overwintering of E. adenophorum and help the weed to gain an advantage in competition with other species [15].…”

Genetic and epigenetic regulation of phenotypic variation in invasive plants – linking research trends towards a unified framework

“…For example, trait plasticity and genetic variation were examined across 16 populations of Crofton weed (Eupatorium adenophorum) in China in a common garden experiment followed by intersimple sequence repeat (ISSR) marker analysis. This study revealed the presence of high phenotypic plasticity of functional traits despite having low genetically based variation (Zhao et al 2012).…”