Reduced intraspecific competition in introduced plant populations suggests a role for self-limitation in invasion success

Ecological diversity depends on mechanisms that promote species coexistence, yet some non-native plants form monospecific stands, suggesting an ability to escape self-limiting processes that constrain native flora. Whereas invasion success is often attributed to enhanced interspecific competition, it may also result from reduced intraspecific competition within introduced populations. Using a controlled greenhouse experiment, I compared competitive outcomes among single native and introduced populations of five plant species (Gleditsia triacanthos, Pinus sylvestris, Paulownia tomentosa, Solidago canadensis, Viola sororia). Individuals were grown in within-range (native × native, introduced × introduced) and across-range (native × introduced) pairings to test whether introduced populations exhibit weaker intraspecific competition. Introduced populations generally showed reduced self-limitation compared with native conspecifics, consistent with relaxed intraspecific density dependence. Be..., Experimental set up
Greenhouse competition experiments were conducted from April to August in 2019 (P. sylvestris), 2020 (G. triacanthos, S. canadensis), and 2021 (P. sylvestris, P. tomentosa, V. sororia). Groups of 4–6 introduced- and home-range seeds of the same species were sown 2 cm apart in 10 × 10 cm pots filled with commercial potting soil (Fox Farm ocean forest, Arcata, CA USA). After germination, seedlings were thinned to ensure a 1:1 competition pairing of similar-sized individuals. Each experiment included three competition pairings: (1) Introduced × Introduced (n = 132 individual plants), (2) Home × Home (n = 148) and (3) Introduced × Home (n = 183). This resulted in a total of n = 463 plant replicates, with variation in species-level replication due to differences in recruitment success: G. triacanthos (n = 160), P. sylvestris (n = 115), P. tomentosa (n = 108), S. canadensis (n = 50) and V. sororia (n = 30). The plants were grown under ambient spring/summer light conditions..., , # Reduced intraspecific competition in introduced plant populations suggests a role for self-limitation in invasion success

Release.from.self.limitation.csv

## Description of the data and file structure

Ident = line identification

Date = year of experiment

Study2 = experimental species (Gleditsia = Gleditsia triacanthos, Pinus = Pinus sylvestris,

```
Paulownia = Paulownia tomentosa, Solidago = Solidago canadensis, Viola = Viola sororia)
```

Habit = woody or (herb)aceous

Total.g = Total plant biomass

Origin = origin range (Inv = introduced, Nat = home range)

Type = type of competition (Intra = intraecotypic; Inter = interecotypic)
, ,