Environmental conditions and community evenness determine the outcome of biological invasion

Abstract

Biological invasion is widely studied, however, conclusions on the outcome of this process mainly originate from observations in systems that leave a large number of experimental variables uncontrolled. Here using a fully controlled system consisting of assembled bacterial communities, we evaluate the degree of invasion and the effect on the community functionality in relation to the initial community evenness under specific environmental stressors. We show that evenness influences the level of invasion and that the introduced species can promote functionality under stress. The evenness-invasibility relationship is negative in the absence and neutral in the presence of stress. Under these conditions, the introduced species is able to maintain the functionality of uneven communities. These results indicate that communities, initially having the same genetic background, in the presence of the same invader, react in a different way with respect to invasibility and functionality depending on specific environmental conditions and community evenness.

Microbial Invasions: The Process, Patterns, and Mechanisms

“…Interestingly, biotic resistance is also implicated in experiments using small diversity gradients. Experiments in model (constructed) communities have corroborated results from larger diversity gradients, indicating that richness [16,17,23] and evenness [18] are indeed factors that contribute to the invasion resistance of natural microbial communities. Overall, a pattern emerges indicating that the survival of an alien species is high when the diversity of the resident community is low and vice versa.…”

“…This idea was later translated to the concept of microbiostasis, which could be further parsed into fungistasis (resistance to fungal invasion) and bacteriostasis (resistance to bacterial invasion) [64,68,69]. Recently, microbial, particularly bacterial, invasions have been studied in several different habitats, including in vitro [15][16][17][18][19]23], in vivo [20], and in situ [15,21,24,26,27,70]. All of these studies included a component of biological diversity, which was able to explain the population dynamics of the invader.…”

“…process [15][16][17][18][19][20][21][22][23][24][25][26][27]. A synthesis of these recent conclusions and their eventual merging into existing ecological and microbiological theory will enhance our understanding of the fundamental processes that govern microbial life.…”

Individual-Based Modelling of Invasion in Bioaugmented Sand Filter Communities

“…The simulation outcomes were explained based on the underlying competition structures (notably by their intransitivity) and the resulting spatial dynamics. Our results highlight the importance of diversity and in particular evenness in stabilizing the community dynamics, in agreement with previous experimental results [47,48].…”

Stable Engraftment of Bifidobacterium longum AH1206 in the Human Gut Depends on Individualized Features of the Resident Microbiome

“…However, although trends were observed, neither total a-diversity (p = 0.0759 for total operational taxonomic units [OTUs] and p = 0.2901 for Shannon diversity index) ( Figure 3B) nor functional richness (p = 0.0759 and p = 0.0818, for single and assembled reads, respectively, data not shown) were significantly higher in non-persisters. Evenness has also been described as a barrier to invasions (De Roy et al, 2013;Wittebolle et al, 2009), but no differences were detected (p = 0.1423) ( Figure 3C). In addition, disturbances have been shown to facilitate invasion of non-native species (Elton, 1958;Kneitel and Perrault, 2007).…”