O'Brien Anna M, Sawers Ruairidh J H, Gasca-Pineda Jaime, Baxter Ivan, Eguiarte Luis E, Ross-Ibarra Jeffrey, Strauss Sharon Y
Center for Population Biology, University of California, Davis, CA, United States.
Department of Evolution and Ecology, University of California, Davis, CA, United States.
Evolution. 2024 Dec 2;78(12):1991-2005. doi: 10.1093/evolut/qpae130.
While biotic interactions often impose selection, species and populations vary in whether they are locally adapted to biotic interactions. Evolutionary theory predicts that environmental conditions drive this variable local adaptation by altering the fitness impacts of species interactions. To investigate the influence of an environmental gradient on adaptation between a plant and its associated rhizosphere biota, we cross-combined teosinte (Zea mays ssp. mexicana) and rhizosphere biota collected across a gradient of decreasing temperature, precipitation, and nutrients in a greenhouse common garden experiment. We measured both fitness and phenotypes expected to be influenced by biota, including concentrations of nutrients in leaves. Independent, main effects of teosinte and biota source explained most variation in teosinte fitness and traits. For example, biota from warmer sites provided population-independent fitness benefits across teosinte hosts. Effects of biota that depended on teosinte genotype were often not specific to their local hosts, and most traits had similar relationships to fitness across biota treatments. However, we found weak patterns of local adaptation between teosinte and biota from colder sites, suggesting environmental gradients may alter the importance of local adaptation in teosinte-biota interactions, as evolutionary theory predicts.
虽然生物相互作用常常施加选择，但物种和种群在是否局部适应生物相互作用方面存在差异。进化理论预测，环境条件通过改变物种相互作用的适合度影响来驱动这种可变的局部适应。为了研究环境梯度对一种植物与其相关根际生物群之间适应的影响，我们在温室共同花园实验中，将大刍草（玉米属墨西哥亚种）与沿着温度、降水量和养分递减梯度收集的根际生物群进行交叉组合。我们测量了预期受生物群影响的适合度和表型，包括叶片中的养分浓度。大刍草和生物群来源的独立主效应解释了大刍草适合度和性状的大部分变异。例如，来自较温暖地点的生物群在所有大刍草宿主上都提供了与种群无关的适合度益处。依赖于大刍草基因型的生物群效应通常并非特定于其本地宿主，并且大多数性状在不同生物群处理中与适合度具有相似的关系。然而，我们发现大刍草与来自较寒冷地点的生物群之间存在微弱的局部适应模式，这表明环境梯度可能如进化理论所预测的那样，改变大刍草 - 生物群相互作用中局部适应的重要性。
