Data from: Lobelia siphilitica plants that escape herbivory in time also have reduced latex production

Flowering phenology is an important determinant of a plant’s reproductive success. Both assortative mating and niche construction can result in the evolution of correlations between phenology and other reproductive, functional, and life history traits. Correlations between phenology and herbivore defence traits are particularly likely because the timing of flowering can allow a plant to escape herbivory. To test whether herbivore escape and defence are correlated, we estimated phenotypic and genetic correlations between flowering phenology and latex production in greenhouse-grown Lobelia siphilitica L. (Lobeliaceae). Lobelia siphilitica plants that flower later escape herbivory by a specialist pre-dispersal seed predator, and thus should invest fewer resources in defence. Consistent with this prediction, we found that later flowering was phenotypically and genetically correlated with reduced latex production. To test whether herbivore escape and latex production were costly, we also measured four fitness correlates. Flowering phenology was negatively genetically correlated with three out of four fitness estimates, suggesting that herbivore escape can be costly. In contrast, we did not find evidence for costs of latex production. Generally, our results suggest that herbivore escape and defensive traits will not evolve independently in L. siphilitica.

开花物候（flowering phenology）是决定植物繁殖成功的关键因素。选型交配（assortative mating）与生态位构建（niche construction）均可促成物候与其他繁殖、功能及生活史性状间相关性的演化。物候与植食动物防御性状（herbivore defence traits）间的相关性尤为常见，这是因为开花时间可赋予植物逃避植食作用的能力。为验证植食逃避与防御性状是否存在相关性，我们对温室栽培的大花半边莲（Lobelia siphilitica L.，半边莲科Lobeliaceae）的开花物候与乳汁产量（latex production）间的表型相关性与遗传相关性（phenotypic and genetic correlations）进行了估算。开花较晚的大花半边莲可逃避专性散前种子捕食者（specialist pre-dispersal seed predator）的取食，因此其在防御相关的资源投入理应更少。与该预测相符，我们发现开花较晚与乳汁产量降低存在表型及遗传相关性。为验证植食逃避与乳汁产量是否存在适合度代价，我们还测定了4项适合度相关指标（fitness correlates）。开花物候与4项适合度估算指标中的3项呈遗传负相关（negatively genetically correlated），这表明植食逃避可能存在适合度代价。与之相反，我们未发现乳汁产量存在适合度代价的相关证据。总体而言，本研究结果表明，在大花半边莲中，植食逃避与防御性状不会独立演化。