The evolution of immune function in decorated crickets

While dietary macronutrients are known to regulate insect immunity, few studies have examined their evolutionary effects. Here, we evaluate this relationship in the cricket Gryllodes sigillatus by maintaining replicate populations on four diets differing in protein (P) to carbohydrate (C) ratio (P- or C-biased) and nutritional content (low- or high-nutrition) for >37 generations. We split each population into two; one maintained on their evolution diet and the other switched to their ancestral diet. We also maintained populations exclusively on the ancestral diet (baseline). After three generations, we measured three immune parameters in males and females from each population. Immunity was higher on P-biased than C-biased diets and on low- versus high-nutrition diets, although the latter was most likely driven by compensatory feeding. These patterns persisted in populations switched to their ancestral diet, indicating genetic divergence. Crickets evolving on C-biased diets had lower immunity than the baseline, whereas their P-biased counterparts had similar or higher immunity than the baseline, indicating that populations evolved with dietary manipulation. While females exhibited superior immunity for all assays, the sexes showed similar immune changes across diets. Our work highlights the important role that macronutrient intake plays in the evolution of immunity in the sexes. Methods We measured immune parameters (hemocyte count, zone of inhibition and PO activity) in male and female crickets from replicate populations that have been evolving on diets differing in the ratio of protein to carbohydrates and total caloric content. Data on these immune parameters were compressed to a mean for each sex per population for final data analysis. Usage notes Data can be open in Microsoft Excel. The data is contained in two separate tabs. The first tab contains all the data from the evolution diet populations. The second tab contains all the data pertaining to the control populations (SCD).尽管膳食宏量营养素（dietary macronutrients）已被证实可调控昆虫免疫，但目前鲜有研究探讨其对昆虫免疫的演化影响。本研究以装饰蟋（Gryllodes sigillatus）为实验对象，将其重复种群饲养于四种不同蛋白质（protein）与碳水化合物（carbohydrate）比例（P偏倚或C偏倚）及营养水平（低营养或高营养）的膳食中，持续演化超过37代，以此探究二者的关联。我们将每个种群划分为两组：一组继续维持其演化膳食饲养，另一组转换至祖先膳食。此外，我们还设置了仅以祖先膳食饲养的种群作为基线对照（baseline）。历经三代饲养后，我们测定了每个种群雌雄个体的三项免疫指标。结果显示，P偏倚膳食组的免疫水平显著高于C偏倚膳食组；低营养膳食组的免疫水平亦高于高营养膳食组，不过后者的差异大概率由补偿性摄食（compensatory feeding）所介导。该差异模式在转换至祖先膳食的种群中依然保留，表明种群已发生遗传分化（genetic divergence）。以C偏倚膳食演化的装饰蟋，其免疫水平低于基线对照；而P偏倚膳食组的对应个体免疫水平与基线对照相当甚至更高，这表明种群在膳食操控下发生了适应性演化。尽管所有测定中雌性个体的免疫水平均优于雄性，但两性在不同膳食条件下的免疫变化趋势并无显著差异。本研究揭示了宏量营养素摄入在两性免疫演化过程中发挥的关键作用。 方法 我们测定了在不同蛋白质与碳水化合物比例及总热量含量的膳食中持续演化的重复种群雌雄个体的三项免疫指标：血细胞计数（hemocyte count）、抑菌圈直径（zone of inhibition）及酚氧化酶（phenol oxidase，PO）活性。为开展最终数据分析，我们将每个种群各性别的免疫指标数据合并为均值，用于后续统计分析。 使用说明 本数据集可使用微软Excel（Microsoft Excel）打开，数据分为两个独立工作表：第一个工作表包含演化膳食种群的全部实验数据，第二个工作表则包含所有与对照种群（SCD）相关的数据。