Data from: Indirect effects drive evolutionary responses to global change

Anthropogenic environmental changes pose significant threats to plant and animal populations. These changes also may affect the evolution of natural populations either directly or indirectly by altering the outcome of species interactions that are important drivers of evolution. This latter indirect pathway may be especially important for evolutionary responses to elevated atmospheric CO2 concentrations (eCO2), which appear to have minimal direct effects on plant evolution but have large effects on interspecific interactions, such as competition. We manipulated competitive and CO2 environments of experimental Arabidopsis thaliana populations to test whether eCO2 alters evolutionary trajectories indirectly by altering selection imposed by competitors. We found that interspecific competition increased selection on growth traits, reduced heritabilities, and altered genetic covariances between traits and that the magnitude of these effects depended upon the CO2 environment. Although eCO2 had minimal direct effects on evolutionary processes, eCO2 typically reduced the strength of selection imposed by competitors and, therefore, relaxed selection on plant traits when competitors were present. Our results indicate that global changes may affect plant evolution indirectly by altering competitive interactions and underscore the importance of conducting research in natural communities when attempting to predict population responses to global change.

人为活动驱动的环境变化对动植物种群构成显著威胁。此类变化还可通过改变作为进化关键驱动力的物种相互作用结果，直接或间接影响自然种群的演化。其中这一间接路径对大气二氧化碳浓度升高（elevated atmospheric CO2 concentrations，简称eCO2）下的演化响应尤为关键：现有研究表明，eCO2对植物演化的直接影响极小，却会对种间相互作用（如种间竞争）产生显著调控效应。本研究通过操控实验拟南芥（Arabidopsis thaliana）种群的竞争环境与二氧化碳浓度环境，旨在验证eCO2是否可通过改变竞争者施加的选择压力，间接改变种群的演化轨迹。研究结果显示：种间竞争提升了对植物生长性状的选择强度，降低了性状的遗传力，并改变了性状间的遗传协方差；且上述效应的强弱依赖于二氧化碳浓度环境。尽管eCO2对演化过程的直接影响微弱，但其通常会削弱竞争者施加的选择强度，因此在存在竞争者的情况下，会缓解对植物性状的选择压力。本研究结果表明，全球变化可通过改变种间竞争相互作用间接影响植物演化，同时也凸显了在预测种群对全球变化的响应时，于自然群落中开展相关研究的重要性。