Data from: Evidence for shifts to faster growth strategies in the new ranges of invasive alien plants

Understanding the processes underlying the transition from introduction to naturalisation and spread is an important goal of invasion ecology. Release from pests and pathogens in association with capacity for rapid growth are thought to confer an advantage for species in novel regions. We assessed leaf herbivory and leaf-level traits associated with growth strategy in the native and exotic ranges of 13 invasive plant species from 256 populations. Species were native to either the Western Cape region of South Africa, south-western Australia, or south-eastern Australia and had been introduced to at least one of the other regions or to New Zealand. We tested for evidence of herbivore release and shifts in leaf traits between native and exotic ranges of the 13 species. Across all species, leaf herbivory, specific leaf area and leaf area were significantly different between native and exotic ranges while there were no significant differences across the 13 species found for leaf mass, assimilation rate, dark respiration or foliar nitrogen. Analysis at the species- and region-level showed that eight out of 13 species had reduced leaf herbivory in at least one exotic region compared to its native range. Six out of 13 species had significantly larger specific leaf area (SLA) in at least one exotic range region and 5 of those 6 species experienced reduced leaf herbivory. Increases in SLA were underpinned by increases in leaf area rather than reductions in leaf mass. No species showed differences in the direction of trait shifts from the native range between different exotic regions. This suggests that the driver of selection on these traits in the exotic range is consistent across regions, and hence is most likely to be associated with factors linked with introduction to a novel environment, such as release from leaf herbivory, rather than with particular environmental conditions. Synthesis: These results provide evidence that introduction of a plant species into a novel environment commonly results in a reduction in the top-down constraint imposed by herbivores on growth, allowing plants to shift towards a faster growth strategy which may result in an increase in population size and spread and consequently to invasive success.

Usage Notes
Leaf trait data for native and exotic rangesData of leaf traits for 13 invasive species collected in their native and exotic rangesLeishman Cooke Richardson.csv

洞悉物种从引入至本土化及扩散过程中的内在机制，是入侵生态学领域的一项重要目标。伴随害虫和病原体的释放以及快速生长能力的存在，被认为赋予物种在新区域中的竞争优势。本研究评估了13种入侵植物物种（共256个种群）在其原生及引入范围内的叶片食草性和与生长策略相关的叶片性状。这些物种原生于南非开普敦西部、澳大利亚西南部或澳大利亚东南部，并已被引入至至少其他一个区域或新西兰。我们针对这13种物种的原生及引入范围，检验了食草动物释放和叶片性状的变化。在所有物种中，叶片食草性、特定叶面积和叶面积在原生和引入范围内存在显著差异，而叶片质量、同化速率、暗呼吸或叶片氮含量在13个物种中均未发现显著差异。在物种和区域层面上进行分析显示，13种物种中有8种在至少一个引入区域中相较于其原生范围，叶片食草性有所降低。13种物种中有6种在至少一个引入区域中具有显著更大的特定叶面积（SLA），其中5种经历了叶片食草性的降低。SLA的增加是由叶片面积的增加而非叶片质量的减少所支撑。没有物种在不同引入区域中显示出从原生范围到性状变化方向的差异。这表明，这些性状在外引入区域的选择驱动因素在各个区域间是一致的，因此最可能与引入新环境相关的因素相关，如叶片食草动物释放，而非特定的环境条件。综合分析：这些结果为植物物种引入新环境通常导致由食草动物施加的下行限制减少提供了证据，使得植物得以转向更快速的生长策略，这可能进而导致种群数量和扩散的增加，最终促成入侵的成功。