Different effects of invader-native phylogenetic relatedness on invasion success and impact: a meta-analysis of Darwin's naturalization hypothesis

Abstract

Darwin's naturalization hypothesis (DNH), which predicts that alien species more distantly related to native communities are more likely to naturalize, has received much recent attention. The mixed findings from empirical studies that have tested DNH, however, seem to defy generalizations. Using meta-analysis to synthesize results of existing studies, we show that the predictive power of DNH depends on both the invasion stage and the spatial scale of the studies. Alien species more closely related to natives tended to be less successful at the local scale, supporting DNH; invasion success, however, was unaffected by alien-native relatedness at the regional scale. On the other hand, alien species with stronger impacts on native communities tended to be more closely related to natives at the local scale, but less closely related to natives at the regional scale. These patterns are generally consistent across different ecosystems, taxa and investigation methods. Our results revealed the different effects of invader-native relatedness on invader success and impact, suggesting the operation of different mechanisms across invasion stages and spatial scales.

Keywords: Darwin's naturalization conundrum; biological invasions; invasion stage; meta-analysis; pre-adaptation hypothesis; spatial scale.

Figure 1.

Different effects of invader–native phylogenetic relatedness on invader success and impact for both local and regional scales. Shown are the mean effect sizes (±bias-corrected 95% bootstrap confidence intervals) of the relationships between invader–native phylogenetic relatedness and invader success/impact. Studies were classified into local and regional studies. Mean effect sizes were calculated as Fisher's z-transformations of correlation coefficients between relatedness and invasion success/impact. Values in parentheses represent the sample sizes. Positive mean effect sizes are consistent with the PAH, and negative mean effect sizes are consistent with DNH.

Figure 2.

The significant negative relationship between invader–native phylogenetic relatedness and invader success at the local scale, but not the regional scale. Shown are the mean effect sizes (±bias-corrected 95% bootstrap confidence intervals) of the relationships between invader–native phylogenetic relatedness and invader success. Local and regional studies were sub-classified according to ecosystem type (aquatic and terrestrial), taxa (microorganisms, animals and plants) and method of investigation (experimental and observational). For other details see figure 1.

Figure 3.

The positive and negative relationship between invader–native phylogenetic relatedness and invader impact at the local and regional scales, respectively. Shown are the mean effect sizes (±bias-corrected 95% bootstrap confidence intervals) of the relationships between invader–native phylogenetic relatedness and invader impact. Local and regional studies were sub-classified according to ecosystem type (aquatic and terrestrial), taxa (microorganisms, animals and plants) and method of investigation (experimental and observational). For other details see figure 1.