Data and scripts from: Replacement drives native β-diversity of British avifauna, while richness differences shape alien β-diversity

Aim: We explored the range shifts of alien and native birds, the responses
of alien and native β-diversity to abiotic factors, and the effect of
native diversity on alien β-diversity in two time periods. Location: Great
Britain. Time period: 1968–1972, 2007–2011. Taxa studied: Breeding birds.
Methods: We estimated range shifts of alien and native species between the
periods 1968–1972 and 2007–2011. Following, β-diversity of alien and
native communities was estimated by Jaccard pairwise index (βtot) and
partitioned into richness difference and replacement component for each
period. We built abiotic Generalized Dissimilarity Models including
abiotic factors for alien and native βtot and their components and a
biotic model for aliens including native taxonomic and functional
diversity as predictors. Results: Most alien and half native species
expanded into new regions during the 40-year period. The native species
range shifts did not exhibit a clear pattern along the longitudinal or
latitudinal gradient, while alien species tended to move north-westwards.
The richness difference was the dominant component of alien β-diversity,
and the replacement component contributed mostly to native β-diversity.
Alien β-diversity responded similarly, but less strongly than native
β-diversity, to the abiotic gradients. Temperature-related variables,
distance, and precipitation were the most important abiotic drivers of
native and alien β-diversity. The biotic model of alien β-diversity
explained more deviance than the abiotic model. Main conclusions: Alien
species expanded into new regions over the 40 years, with alien
β-diversity driven mostly by species gains. The effect of environmental
filtering on alien communities was weaker compared to native communities
but was slightly reinforced in the second period compared to the first
period, highlighting the role of environmental change in shaping diversity
patterns. Native diversity played a key role in driving alien β-diversity,
through biotic interactions or/and by reflecting climatic suitability or
niche availability for aliens.