Climate and genome size shape the intraspecific variation in ecological adaptive strategies of a cosmopolitan grass species

Intraspecific trait variation, essential to Darwin's mechanism of natural selection, has been widely examined for single characters. However, intraspecific variation of adaptive strategies which represent trade‐offs among multiple functional traits has received less attention, particularly for species that are globally distributed or invasive. Grime's competitor, stress tolerator and ruderal (CSR) scheme, well validated in the context of alien species invasions, provides both the theory and quantitative methodology to investigate adaptive strategies. Here, we quantified the intraspecific CSR strategy scores of a worldwide collection of 89 Phragmites australis genotypes which were cultivated in a common garden. We assessed the relationships between intraspecific variation in CSR strategy scores, genome size and climate of origin and tested whether the invasive and native lineages differ in CSR strategies. Substantial variation in intraspecific adaptive strategy, characterized mainly in C‐ and S‐selection, was observed. As expected, C‐, S‐ and R‐scores showed clear latitudinal clines and were strongly related to either genome size or climate of origin. Furthermore, invasive lineages were more stress adapted than native lineages. We conclude that the adaptive strategy of this perennial wetland grass varies globally, and its genotypes are surprisingly more stress tolerant in the invaded range where it was first detected ~150 years ago. Read the free Plain Language Summary for this article on the Journal blog. 摘要 物种的种内性状变异对于自然选择机制至关重要。当前对于单一性状变异的研究已比较广泛，然而，对代表多功能性状间权衡的生态适应策略的种内变异的关注较少，特别是对于全球广布种或是入侵性物种而言。Grime的竞争(C)−耐胁迫(S)−杂草(R)策略(CSR)理论为研究适应性策略提供了理论和定量方法，并在外来物种入侵领域得到了较好的验证。 我们量化了在同质园中栽培的89个来自全球的芦苇基因型的种内CSR策略得分，评估了CSR策略得分的变异、基因组大小和芦苇基因型来源地气候之间的关系，并检验了入侵和本土谱系是否存在CSR策略的差异。 我们发现，全球层面上，芦苇的种内适应策略以C‐和S‐选择为主要特征并存在较大的变异。CSR策略得分显示出显著的纬度梯度格局，且与基因组大小或起源地气候紧密相关。 研究表明，芦苇这种多年生湿地草本植物的适应性策略在全球范围内具有较高的种内变异。此外，约150年前由欧亚大陆引入、当前北美洲最主要的入侵性芦苇谱系的耐胁迫能力显著高于当地本土芦苇。 Read the free Plain Language Summary for this article on the Journal blog.