Data from: Revisiting Darwin’s naturalization conundrum: explaining invasion success of non-native trees and shrubs in southern Africa

1. Invasive species are detrimental ecologically and economically. Their negative impacts in Africa are extensive and call for a renewed commitment to better understand the correlates of invasion success. 2. Here, we explored several putative drivers of species invasion among woody non-native trees and shrubs in southern Africa, a region of high floristic diversity. We tested for differences in functional traits between plant categories using a combination of phylogenetic independent contrasts and a simulation-based phylogenetic anova. 3. We found that non-native species generally have longer flowering duration compared with native species and are generally hermaphroditic, and their dispersal is mostly abiotically mediated. We also revealed that non-native trees and shrubs that have become invasive are less closely related to native trees and shrubs than their non-invasive non-native counterparts. Non-natives that are more closely related to the native species pool may be more likely to possess traits suited to the new environment in which they find themselves and thus have greater chance of establishment. However, successful invaders are less closely related to the native pool, indicating evidence for competitive release or support for the vacant niche theory. 4. Synthesis. Non-native trees and shrubs in southern Africa are characterized by a suite of traits, including long flowering times, a hermaphroditic sexual system and abiotic dispersal, which may represent important adaptations promoting establishment. We suggest that differences in the evolutionary distances separating the native species pool from invasive and non-invasive species might help resolve Darwin's naturalization conundrum.

1. 入侵物种会对生态系统与经济造成不利影响。它们在非洲的负面效应波及范围广泛，亟需学界加大研究投入，以更深入地解析入侵成功的相关关联因素。
2. 本研究针对植物区系多样性丰富的南部非洲地区的木本非原生树木与灌木，探究了若干潜在的物种入侵驱动因子。我们结合系统发育独立对比（phylogenetic independent contrasts）与基于模拟的系统发育方差分析（phylogenetic ANOVA），检验了不同植物类群间的功能性状差异。
3. 研究结果显示，相较于本土物种，非本土物种通常花期更长，且多为雌雄同株（hermaphroditic），其传播方式大多为非生物传播（abiotic dispersal）。此外我们发现，已成功入侵的木本非原生树木与灌木，相较于非入侵性的非本土同类群，与本土植物类群的亲缘关系更为疏远。与本土物种种库亲缘关系较近的非本土物种，或许更易拥有适配新环境的功能性状，因此其定植成功率更高。然而，成功入侵的物种与本土物种种库的亲缘关系反而更疏远，这一结果既为竞争释放（competitive release）提供了佐证，也支持了生态位空缺理论（vacant niche theory）。
4. 研究总结：南部非洲的木本非原生树木与灌木具有一系列标志性功能性状，包括较长的花期、雌雄同株的繁殖系统以及非生物传播方式，这些性状或为促进其定植的重要适应性特征。我们认为，本土物种种库与入侵性、非入侵性非本土物种间的进化距离差异，或有助于解析达尔文归化悖论（Darwin's naturalization conundrum）。