Abstract：
Loss of species in food webs can set in motion a cascade of additional (secondary) extinctions. A species\' position in a food web (e.g. its trophic level or number of interactions) is known to affect its ability to persist following disturbance. These simple measures, however, offer only a coarse description of how species fit into their community. One would therefore expect that more detailed structural measures such as participation in three-species motifs (meso-scale structures which provide information on a species\' direct and indirect interactions) will also be related to probability of persistence. Disturbances affecting the basal resources have particularly strong effects on the rest of the food web. However, how disturbances branch out and affect consumer persistence depends on the structural pattern of species interactions in several steps. The magnitude, for example, the proportion of basal resources lost, will likely also affect the outcome. Here, we analyse whether a consumer\'s risk of secondary extinction after the removal of basal resources depends on the consumer\'s motif participation and how this relationship varies with the severity of disturbance. We show that consumer species which participate more frequently in the direct competition motif and less frequently in the omnivory motif generally have higher probability of persistence following disturbance to basal resources. However, both the strength of the disturbance and the overall network structure (i.e. connectance) affect the strength and direction of relationships between motif participation and persistence. Motif participation therefore captures important trends in species persistence and provides a rich description of species\' structural roles in their communities, but must be considered in the context of network structure as a whole and of the specific disturbance applied.
摘要：
食物网中物种的丧失可能会引发一系列额外的（二次）灭绝。已知食物网中的物种位置（例如其营养水平或相互作用的数量）会影响其在干扰后持续的能力。这些简单的措施，然而,只提供一个关于物种如何适应他们的社区的粗略描述。因此，人们会期望更详细的结构措施，例如参与三物种基序（提供物种直接和间接相互作用信息的中尺度结构）也将与持久性的可能性有关。影响基础资源的干扰对食物网的其余部分具有特别强的影响。然而,干扰如何分支并影响消费者的持久性取决于物种相互作用的结构模式。幅度,例如,基础资源损失的比例，也可能会影响结果。这里,我们分析消费者在去除基础资源后二次灭绝的风险是否取决于消费者的主题参与，以及这种关系如何随干扰的严重程度而变化。我们表明，在直接竞争基序中参与频率较高而在杂食基序中参与频率较低的消费物种通常在基础资源受到干扰后具有较高的持久性可能性。然而,干扰的强度和整体网络结构（即连通性）都会影响主题参与和持久性之间关系的强度和方向。因此，基序参与捕获了物种持久性的重要趋势，并对物种在其群落中的结构作用进行了丰富的描述。但必须在整个网络结构和所应用的特定干扰的背景下考虑。
