Fig. 1

Possible trajectories of microbiome modifications during invasion. This figure presents different possible trajectories of the microbiome of two invasive species (A in red and B in grey) in their native (dashed ellipses) and non-native (continuous ellipses) ranges. Each ellipse represents the dissimilarity in microbiome composition between individuals from a given species and population, as often represented in an ordination. The microbiome of each species can become more or less variable in the non-native range, as depicted by the size of the ellipses, while the non-native microbiome can be more or less dissimilar to the native one, as depicted by the arrows and the degree of overlap between native and non-native ellipses. Ultimately, these intra-specific microbiome modifications could result in differentiation or homogenization of the microbiome between the species. These examples highlight the possibility of a similar inter-species outcome arising from different combinations of intra-specific trajectories. This framework can be applied to study inter-specific modifications of other ecological traits than the microbiome (i.e. diet breadth, isotopic niche, morphological or behavioral traits) and in other contexts than invasions (e.g. response to disturbance)