Data from: Genetic variation and evolution of secondary compounds in native and introduced populations of the invasive plant Melaleuca quinquenervia

We examined multivariate evolution of 20 leaf terpenoids in the invasive plant Melaleuca quinquenervia in a common garden experiment. While most compounds, including 1,8-Cineole and Viridiflorol, were reduced in home compared with invaded range genotypes, consistent with an evolutionary decrease in defense, one compound (E-Nerolidol) was greater in invaded than home range genotypes. Nerolidol was negatively genetically correlated with Cineole and Viridiflorol, and the increase in this compound in the new range may have been driven by this negative correlation. There was positive selection on all three focal compounds, and a loss of genetic variation in introduced range genotypes. Selection skewers analysis predicted an increase in Cineole and Viridiflorol and a decrease or no change in Nerolidol, in direct contrast to the observed changes in the new range. This discrepancy could be due to differences in patterns of selection, genetic correlations or the herbivore communities in the home versus introduced ranges. While evolutionary changes in most compounds were consistent with the Evolution of Increased Competitive Ability Hypothesis, changes in other compounds as well as selection patterns were not, indicating that it is important to understand selection and the nature of genetic correlations to predict evolutionary change in invasive species.

本研究通过同质园（common garden）实验，探究了入侵植物五脉白千层（Melaleuca quinquenervia）叶片中20种萜类化合物的多变量演化模式。研究发现，多数萜类化合物（包括1,8-桉叶素（1,8-Cineole）与绿花白千层醇（Viridiflorol））在原产地种群中的含量显著低于入侵范围种群，这与防御能力的演化降低假说相一致；但反式-橙花叔醇（E-Nerolidol）在入侵范围种群中的含量显著高于原产地种群。基因层面分析显示，橙花叔醇（Nerolidol）与1,8-桉叶素、绿花白千层醇之间存在负遗传相关，入侵范围种群中该化合物的含量上升可能正是由这种负遗传相关所驱动。本研究还观测到，三种目标化合物均受到正向选择，且入侵范围种群的遗传变异出现丢失。选择偏斜分析预测，1,8-桉叶素与绿花白千层醇的含量会上升，而橙花叔醇的含量会下降或无变化，这与入侵范围种群中实际观测到的变化完全相悖。这种差异可能源于原产地与入侵范围之间的选择模式、遗传相关结构以及植食性昆虫群落的差异。尽管多数萜类化合物的演化变化符合竞争能力增强演化假说（Evolution of Increased Competitive Ability Hypothesis），但部分化合物的变化以及选择模式却与该假说不符，这表明：要准确预测入侵物种的演化变化，必须深入理解选择作用的机制与遗传相关的本质。