Phenotypic plasticity of Alternanthera philoxeroides in response to root neighbors of kin: Introduced vs. native genotypes

doi:10.17520/biods.2020044

Abstract

Abstract:

Plant root neighbors can induce plastic responses, thereby altering root biomass allocation and other functional traits even while available resources remain constant. The evolution of plasticity hypothesis demonstrates that populations in the introduced range of an invasive species have evolved greater plasticity than populations in the native range. Most studies focus on plastic responses of alien plants to light, water, nutrition and nature enemies. However, plastic responses to root neighbors in alien plants has not been studied. We conducted a common garden experiment using five introduced (the United States of America, USA) and five native (Argentina) genotypes of Alternanthera philoxeroides (alligator weed) to compare fitness and functional traits responses to root neighbors of the same genotype plants (kin). We found that introduced genotypes had an increased root to shoot ratio (RSR) and specific leaf area (SLA) when root neighbors were present while the native genotypes showed the opposite responses. However, introduced and native genotypes showed no difference in total biomass, storage root biomass, specific stem length (SSL) and branching intensity (BI). In addition, when root neighbors were present, A. philoxeroides increased in total biomass (+9.9%) and storage root biomass (+13.9%) and decreased in SSL (-9.5%) than when grown without root neighbors. Introduced genotypes showed an increase in total biomass (+62.0%), storage root biomass (+58.9%), and reduction of SSL (-28.5%) and BI (-42.8%) than native genotypes. Our results suggest that functional trait plasticity responses related to resource utilization (i.e. RSR and SLA) showed opposite patterns between introduced and native genotypes, but fitness and functional trait plasticity responses related to plant type (i.e. SSL and BI) showed no difference among introduced and native genotypes.

Key words: neighbor effect, intra-genotypic interaction, phenotypic plasticity, plant invasion, evolution

Liangrui Yu, Zhengcai Zhu, Xiaoyun Pan. Phenotypic plasticity of Alternanthera philoxeroides in response to root neighbors of kin: Introduced vs. native genotypes[J]. Biodiv Sci, 2020, 28(6): 651-657.

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URL: https://www.biodiversity-science.net/EN/10.17520/biods.2020044

https://www.biodiversity-science.net/EN/Y2020/V28/I6/651

Figures/Tables 3

Fig. 1 Schematic diagram of experimental setup for plants of kins planted in pots with or without root neighbors. (a) Root neighbors were absent; (b) Root neighbor were present.

Table 1 Effects of origin (i.e. introduced vs native) and root neighbors (i.e. absent vs present) and their interaction on fitness traits (total biomass, storage root biomass) and functional traits (root to shoot ratio (RSR), specific leaf area (SLA), specific stem length (SSL) and branching intensity (BI)) of Alternanthera philoxeroides. Significant effects are marked in bold. Marginally significant effects are marked in italics and bold.

变异来源 Source of variation	总生物量 Total biomass		贮藏根生物量 Storage root biomass		根冠比 RSR		比叶面积 SLA		比茎长 SSL		分枝强度 BI
变异来源 Source of variation	c²	P	c²	P	c²	P	c²	P	c²	P	c²	P
来源地 Origin	6.767	0.009	3.663	0.056	0.213	0.645	2.373	0.123	5.408	0.020	3.377	0.066
邻体根系 Root neighbor	11.513	0.001	8.456	0.004	0.938	0.333	0.592	0.442	18.183	0.000	0.148	0.700
来源地 × 邻体根系 Origin × root neighbor	0.501	0.479	2.410	0.121	2.911	0.088	7.165	0.007	1.240	0.265	0.037	0.847

Fig. 2 Responses of introduced (USA) and native (Argentina) genotypes of Alternanthera philoxeroides to the root neighbors. (a) Total biomass; (b) Storage root biomass; (c) Root to shoot ratio (RSR); (d) Specific leaf area (SLA); (e) Specific stem length (SSL); (f) Branching intensity (BI). Error bars indicate 95% confidence intervals. * indicate significant differences in responses between introduced and native genotypes. ? indicate marginally significant differences in responses between introduced and native genotypes.

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