Division of Labor Brings Greater Benefits to Clones of Carpobrotus edulis in the Non-native Range: Evidence for Rapid Adaptive Evolution.

Sergio R Roiloa,Josefina G Campoy,Rodolfo Barreiro,Rubén Retuerto,Ana Novoa

doi:10.3389/fpls.2016.00349

Abstract

Why some species become invasive while others do not is a central research request in biological invasions. Clonality has been suggested as an attribute that could contribute to plant invasiveness. Division of labor is an important advantage of clonal growth, and it seems reasonable to anticipate that clonal plants may intensify this clonal attribute in an invaded range because of positive selection on beneficial traits. To test this hypothesis, we collected clones of Carpobrotus edulis from native and invasive populations, grew pairs of connected and severed ramets in a common garden and under negative spatial covariance of nutrients and light to induce division of labor, and measured biomass allocation ratios, final biomass, and photochemical efficiency. Our results showed that both clones from the native and invaded range develop a division of labor at morphological and physiological level. However, the benefit from the division of labor was significantly higher in apical ramets from the invaded range than in ramets from the native area. This is a novel and outstanding result because it provides the first evidence that the benefit of a key clonal trait such as division of labor may have been subjected to evolutionary adaptation in the invaded range. The division of labor can therefore be considered an important trait in the invasiveness of C. edulis. An appropriate assessment of the influence of clonal traits in plant invasions seems key for understanding the underlying mechanisms behind biological invasions of new environments.

Highlights

The establishment of invasive alien species modifies the stability and functioning of populations, communities, and ecosystems, displaces native species and, as consequence, promotes a loss of biodiversity (Vitousek et al, 1996; Mack et al, 2000; Strayer, 2012)
The proportion of biomass allocated to roots by older and younger ramets, as determined by the root to shoot ratio (RSR), was significantly affected by the connection treatment (Table 1)
As proposed in our hypotheses, we found that connection significantly increase the mass allocated to roots (RSR) in older ramets subjected to high nutrients and low light conditions, denoting a specialization to acquire the relatively abundant below-ground resource

Summary

Introduction

The establishment of invasive alien species modifies the stability and functioning of populations, communities, and ecosystems, displaces native species and, as consequence, promotes a loss of biodiversity (Vitousek et al, 1996; Mack et al, 2000; Strayer, 2012). Many of the most aggressive invasive plant species show clonal growth, and a recent study has highlighted the importance of traits related to clonal propagation in successful invaders (Song et al, 2013). Key aspects such as physiological integration or the capacity for a division of labor make a significant contribution to the success of clonal plants in a wide range of habitats (Hartnett and Bazzaz, 1983; Slade and Hutchings, 1987; Alpert and Stuefer, 1997; Klimes et al, 1997; Saitoh et al, 2002; Roiloa et al, 2007). We aim to add new evidence that may help to elucidate the role of clonal traits in plant invasions

Objectives

Methods

Results

Conclusion