Legends
Fig. 1. Community responses to species invasion along environmental gradients for each food web module. (a-e) Trophic position of the invader (blue circle) relative to the resident species (green circles) under apparent competition (AC, panels a, f and l), exploitative competition (EC, panels b, g and m), trophic chain (TC, panels c, h and n), and intraguild predation (IGP) with invading consumer (IGPC, panels d, i and o) and with invading predator (IGPP, panels e, j and p). Invasion outcomes (panels f-j) as in Box 1 summarize community changes with gain in diversity (ΔD > 0), no net change (ΔD = 0) or loss in diversity (ΔD < 0) after invasion. Regime statesSRES.SINV (panels l-p) summarize all possible combinations of the system qualitative state prior to (SRES ) and after (SINV ) invasion leading to a gain of stability (stabilizing, ΔS > 0), no net change (neutral, ΔS = 0) or loss of stability (destabilizing, ΔS < 0) after invasion. Regime state abbreviations: N = no species present, O = population oscillations with at least two species present, E = 1 to 3 species in stable equilibrium. Species body mass ratios fixed at α = β = 10.
Fig. 2. Module-specific effects of species body mass ratios on the averaged proportions of invasion outcomes that drive local diversity change . Body mass ratio given for (a-c) invader and its resident competitor (d, e) and adjacent trophic levels. Food web modules: (a) AC = apparent competition, (b) EC = exploitative competition, (c) IGP = intraguild predation with invading intraguild prey (β ≤ 1) and invading intraguild predator (β ≥ 1), (d) TC = trophic chain and (e) IGPP = intraguild predation with invading intraguild predator. Species: R = basal resource, C = consumer,P = predator. Symbols denote gain of diversity (squares), no net change (circles) or diversity loss (triangles) following invasions. Colours as in Fig. 1f-j.
Fig. 3. Module-specific effects of species body mass ratios on the averaged proportions of regime states following invasion. Body mass ratio between (a-c) invader and its resident competitor, and (d, e) between adjacent trophic levels. Food web modules and species as in Fig. 1. Regime state abbreviations: N = no species present, O = population oscillations with at least two species present, E = 1 to 3 species in stable equilibrium. Lines = neutral (dotted lines) and non-neutral (solid lines): influence of invader on local stability regime; symbols = gain of stability (squares), neutral change (circle) and loss of stability (triangles) following invasions. Colours identical to Fig. 1l-p.
Fig. 4. Differences in stability change (ΔS)between (a) invasion outcomes and (b) biodiversity change (ΔD) following successful species invasions. Values = cumulative proportions of regime states shown in Fig. S1. Biodiversity change in (b) illustrates the cumulative proportions observed across invasion outcomes in (a) broken by their effect on diversity, i.e. ΔD > 0 for integration, occupancy and rescue, ΔD = 0 for substitution and ΔD < 0 for vulnerability. Change in stability: ΔS < 0, loss of stability; ΔS = 0, no change; ΔS > 0, increase in stability. Note that resistance to invasion (with ΔS= 0 and ΔD = 0) is excluded in both panels.