Mutualistic Interactions and Biological Invasions

Abstract

Mutualisms structure ecosystems and mediate their functioning. They also enhance invasions of many alien species. Invasions disrupt native mutualisms, often leading to population declines, reduced biodiversity, and altered ecosystem functioning. Focusing on three main types of mutualisms (pollination, seed dispersal, and plant-microbial symbioses) and drawing on examples from different ecosystems and from species-and community-level studies, we review the key mechanisms whereby such positive interactions mediate invasions and are in turn influenced by invasions. High interaction generalization is "the norm" in most systems, allowing alien species to infiltrate recipient communities. We identify traits that influence invasiveness (e.g., selfing capacity in plants, animal behavioral traits) or invasibility (e.g., partner choice in mycorrhizas/rhizobia) through mutualistic interactions. Mutualistic disruptions due to invasions are pervasive, and subsequent cascading effects are also widespread. Ecological networks provide a useful framework for predicting tipping points for community collapse in response to invasions and other synergistic drivers of global change. 89

Research on mutualisms between native and non-native partners can contribute critical ecological insights

“…1; Theoharides and Dukes 2007;Richardson and Pyšek 2012). Consistently, most examples of novel mutualisms are both facultative and generalist (Traveset and Richardson 2014). This parallels our contemporary understanding of most native-native mutualisms (Blüthgen et al 2007).…”

“…Ecologically and evolutionarily, mutualisms have shaped many biological invasions and vice versa (recently reviewed by Traveset and Richardson 2014). The importance of mutualisms in facilitating invasion and the potential for mutualism evolution to change as a result of biological invasions are critical areas of study (Kiers et al 2010;Traveset and Richardson 2014).…”

“…The importance of mutualisms in facilitating invasion and the potential for mutualism evolution to change as a result of biological invasions are critical areas of study (Kiers et al 2010;Traveset and Richardson 2014). However, the formation of "novel mutualisms" between native and non-native species also serves as a remarkable opportunity to study the processes governing mutualism formation, failure, and fitness implications.…”

“…However, the formation of "novel mutualisms" between native and non-native species also serves as a remarkable opportunity to study the processes governing mutualism formation, failure, and fitness implications. As they become established in ecological communities, non-native species may enter mutualistic networks, potentially altering community dynamics and ecosystem functions (Traveset and Richardson 2014). Fundamental research in ecology has centered on the role of mutualisms in emergent ecosystem properties-that is, how mutualism formation, structure, and stability may have generated the species combinations and interactions observed in ecosystems today.…”

Impacts of invasive biota in forest ecosystems in an aboveground–belowground context

“…Moreover, different invaders can have positive effects on one another, leading to 'invasional meltdown' (Simberloff and von Holle 1999). For example, invasive woody plants may be dependent on co-invasion by invasion of their mutualists such as nitrogen fixing bacteria or ectomycorrhizal fungi (Nuñez and Dickie 2014;Traveset and Richardson 2014). Recent studies have also shown that invasive mammals can in turn facilitate the dispersal of invasive ectomycorrhizal fungal species required for the successful establishment of invasive tree species, in both Argentina (Nuñez et al 2013) and New Zealand (Wood et al 2015).…”