Social network position experiences more variable selection than weaponry in wild subpopulations of forked fungus beetles

1. The phenotypic expression and fitness consequences of behaviors that are exhibited during social interactions are especially sensitive to their local social context. This context-dependence is expected to generate more variation in the sign and magnitude of selection on social behavior than that experienced by static characters like morphology. Relatively few studies, however, have examined selection on behavioral traits in multiple populations. 2. We estimated sexual selection in the wild to determine if the strength and form of selection on social phenotypes is more variable than that on morphology. 3. We compared selection gradients on social network position, body size, and weaponry of male forked fungus beetles (Bolitotherus cornutus) as they influenced mating success across nine natural subpopulations. 4. Male horn length consistently experienced positive sexual selection. However, the sign and magnitude of selection on individual measures of network centrality (strength and betweenness) differed significantly among subpopulations. Moreover, selection on social behaviors occurred at local scale (“soft selection”), whereas selection on horn length occurred at the metapopulation scale (“hard selection”). 5. These results indicate that an individual with a given social phenotype could experience different fitness consequences depending on the network it occupies. While individuals seem to be unable to escape the fitness effects of their morphology, they may have the potential to mediate the pressures of selection on behavioral phenotypes by moving among subpopulations or altering social connections within a network.

Methods
The data were collected as described in the methods of the paper.  In summary, behavioral interactions were recorded if individuals were within 5 cm of each other, those data were then turned into an association matrix, the simple ratio index was then calcualted based on the observations.  Using the SRI data, social networks were created for each subpopulation.  The uploaded data set is the attribute file with calculated social network metrics (strength, betweeness, and clustering coefficent), fitness measures (number of succesful inseminations, and morphological traits (honrs and elytra size).

1. 社会互动中展现出的行为的表型表达（phenotypic expression）及其适合度后果（fitness consequences），对其所处的局部社会背景尤为敏感。相较于形态学等静态性状，这种情境依赖性预计会使社会行为所受选择的方向和强度产生更大变异。然而，目前在多个种群中开展行为性状选择研究的报道相对较少。
2. 我们在野外环境中评估了性选择（sexual selection），以探究社会表型所受选择的强度与形式是否比形态学性状所受选择具有更高的变异性。
3. 我们针对9个自然亚种群，比较了雄性叉角真菌甲虫（Bolitotherus cornutus）的社会网络位置、体型及雄性武器的选择梯度（selection gradients），这些性状会影响其交配成功率。
4. 雄性角长始终受到正向性选择作用。然而，不同亚种群对个体网络中心性（network centrality）指标（连接强度（strength）与介数中心性（betweenness））的选择方向和强度存在显著差异。此外，社会行为所受选择发生在局域尺度（软选择，soft selection），而角长所受选择则发生在集合种群（metapopulation）尺度（硬选择，hard selection）。
5. 上述结果表明，拥有特定社会表型的个体，其适合度后果会因所处网络的不同而存在差异。尽管个体似乎无法摆脱形态学性状对其适合度的影响，但它们有可能通过在亚种群间移动，或改变网络内的社会联结，来调控行为表型所受的选择压力。
方法
本数据集按照论文所述方法进行采集。简言之，当个体间距离小于5厘米时即记录其行为互动，随后将这些数据转化为关联矩阵（association matrix），并基于观测结果计算简单比率指数（Simple Ratio Index, SRI）。利用SRI数据，我们为每个亚种群构建了社会网络。本次上传的数据集为属性文件（attribute file），其中包含已计算得到的社会网络指标（social network metrics，包括连接强度、介数中心性与聚类系数（clustering coefficient））、适合度指标（fitness measures，即成功授精次数）以及形态学性状（角长与鞘翅大小（elytra size））。