Conspecific Plasticity and Invasion: Invasive Populations of Chinese Tallow (Triadica sebifera) Have Performance Advantage over Native Populations Only in Low Soil Salinity

Candice J Tiu,Leiyi Chen,Shaolin Peng,Evan Siemann

doi:10.1371/journal.pone.0074961

Abstract

Global climate change may increase biological invasions in part because invasive species may have greater phenotypic plasticity than native species. This may be especially important for abiotic stresses such as salt inundation related to increased hurricane activity or sea level rise. If invasive species indeed have greater plasticity, this may reflect genetic differences between populations in the native and introduced ranges. Here, we examined plasticity of functional and fitness-related traits of Chinese tallow (Triadica sebifera) populations from the introduced and native ranges that were grown along a gradient of soil salinity (control: 0 ppt; Low: 5 ppt; Medium: 10 ppt; High: 15 ppt) in a greenhouse. We used both norm reaction and plasticity index (PIv) to estimate the conspecific phenotypic plasticity variation between invasive and native populations. Overall, invasive populations had higher phenotypic plasticity of height growth rate (HGR), aboveground biomass, stem biomass and specific leaf area (SLA). The plasticity Index (PIv) of height growth rate (HGR) and SLA each were higher for plants from invasive populations. Absolute performance was always comparable or greater for plants from invasive populations versus native populations with the greatest differences at low stress levels. Our results were consistent with the “Master-of-some” pattern for invasive plants in which the fitness of introduced populations was greater in more benign conditions. This suggests that the greater conspecific phenotypic plasticity of invasive populations compared to native populations may increase invasion success in benign conditions but would not provide a potential interspecific competitive advantage in higher salinity soils that may occur with global climate change in coastal areas.

Highlights

Extreme climate events, such as hurricanes, are predicted to be more frequent in the future and associated negative impacts on coastal ecosystems have gained increasing attention [1]
Higher abiotic stress tolerance of invasive species compared to native species, which could contribute to invasion success under stressful conditions, can result from intrinsic attributes of the invader or evolution of phenotypic plasticity after introduction to a novel environment [42,43,44]
We found that differences in plasticity between origins varied among traits

Summary

Introduction

Extreme climate events, such as hurricanes, are predicted to be more frequent in the future and associated negative impacts on coastal ecosystems have gained increasing attention [1]. In addition to creating waterlogged and anoxic soils, hurricanes will increase electrolyte concentrations and osmotic potential of the soil solution and create a stressful, high salinity environment for both native and invasive plants [2,3,4,5]. Phenotypic plasticity, the potential of specific traits of a genotype to be expressed differently in distinct environments, is one of the mechanisms by which invasive plants can tolerate wide environmental variation and obtain an advantage in changing environments [6]. Salinity stress may magnify, reduce, or have no effect on invasion success depending on the pattern of an invader’s phenotypic plasticity. Native salt-adapted vegetation can be protected from salt-sensitive exotics by increasing soil salinity in salt marshes when the exotics have relative low fitness in salinity stress [10]

Methods

Results

Conclusion