Developmentally Programmed Division of Labor in the Aquatic Invader Alternanthera philoxeroides Under Homogeneous Soil Nutrients.

Dao-Guo Xi,Wen-Hua You,An-An Hu,Ping Huang,Dao-Lin Du

doi:10.3389/fpls.2019.00485

Abstract

Clonal traits can contribute to plant invasiveness, but little is known about the roles of division of labor (a key clonal trait) in homogeneous habitats. The hypothesis tested is that clonal integration allows division of labor and increases the overall performance of an invasive clonal plant, especially under higher soil nutrients. Clonal fragment pairs of aquatic invader Alternanthera philoxeroides (each with four ramets and a stolon apex) were grown in two homogenous habitats with high or low soil nutrient supply, and with stolon connections being either severed (clonal integration prevented) or kept intact (clonal integration allowed). Results showed that stolon connection allowed the division of labor within the clonal fragment, with basal ramets specializing in acquisition of belowground resources and apical ramets specializing in acquisition of aboveground expansion. Moreover, the capacity for division of labor was greater, which brought the clonal fragments of A. philoxeroides stronger clonal propagation and better performance in high nutrient habitats than in low nutrient habitats. The results supported our hypotheses that the developmentally programmed division of labor may facilitate the clonal expansion of this aggressive invader in some homogeneous habitats with high resource availability.

Highlights

Invasive plants have greatly threatened biodiversity, the environment and economic development worldwide (Mack et al, 2000; Vila et al, 2011; van Kleunen et al, 2015)
Such effects of stolon connection on basal and apical ramets were significantly stronger when A. philoxeroides was grown in high soil nutrients than in low soil nutrients, as demonstrated by the significant effects of nutrient × stolon connection (Figure 2 and Table 1)
Stolon connection significantly decreased the growth of basal ramets (Figures 3A,C,E), whereas the growth of apical ramets were greatly improved by stolon connection, and such positive effects on apical ramets were stronger when A. philoxeroides was grown in high soil nutrient than in low soil nutrient, as demonstrated by the significant effects of nutrient × stolon connection for total stolon length and ramet number (Figures 3B,D,F and Table 1)

Summary

Introduction

Invasive plants have greatly threatened biodiversity, the environment and economic development worldwide (Mack et al, 2000; Vila et al, 2011; van Kleunen et al, 2015). In comparison, when the clone consists of the ramets that are in different developmental stages, or differing in ability to acquire resources, the connected ramets within the clone may get different amounts of resources even with the same external resource supply (Dong et al, 2015) In this case, division of labor and physiological integration between ramets may still increase plant performance even in the homogeneous environments, with relatively older ramets specializing in taking up belowground resources and relatively younger ramets specializing in aboveground resources and spread (Stuefer, 1998; Roiloa et al, 2013). Division of labor is beneficial to clonal plants, the importance of ramet specialization for the invasiveness of clonal plants is still far from clear (Roiloa et al, 2016)

Methods

Results

Conclusion