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.

本研究依托同质园试验（common garden experiment），针对入侵植物白千层（Melaleuca quinquenervia）的20种叶片萜类化合物（leaf terpenoids）开展多变量演化模式分析。与原生分布区的基因型相比，入侵分布区种群的多数化合物——包括1,8-桉叶素（1,8-Cineole）与绿花白千层醇（Viridiflorol）——含量均出现下降，这与植物防御能力演化降低的趋势一致；但反式-橙花叔醇（E-Nerolidol）在入侵分布区基因型中的含量显著更高。橙花叔醇（Nerolidol）与桉叶素、绿花白千层醇存在负遗传相关，入侵分布区中该化合物的含量升高可能正是由这种负遗传相关介导的。三种目标化合物均受到正选择作用，且入侵分布区基因型的遗传变异发生了丢失。选择偏斜分析（selection skewers analysis）预测，桉叶素与绿花白千层醇的含量将升高，而橙花叔醇的含量会降低或无显著变化，这与入侵分布区中实际观测到的变化完全相悖。这种差异可能源于原生分布区与入侵分布区在选择模式、遗传相关关系以及植食性群落结构上的差异。尽管多数化合物的演化变化符合竞争能力增强进化（Evolution of Increased Competitive Ability, EICA）假说，但其余化合物的变化以及选择模式并不契合该假说，这表明若要精准预测入侵物种的演化变化，需充分理解选择作用的机制与遗传相关的本质。