Data from: To pool or not to pool: Pooled metabarcoding does not affect estimates of prey diversity in spider gut content analysis

Gut content metabarcoding has provided important insights into the food
web ecology of spiders, the most dominant terrestrial arthropod predators.
In small invertebrates, like spiders, gut content analysis is often
performed on whole body DNA extracts of individual predators, from which
prey sequences are selectively enriched and sequenced. Since many spider
species are generalist predators, large numbers of samples comprising
individual spider specimens must be analyzed to recover an exhaustive
image of a spider species’ prey spectrum, which is costly and
time-consuming. Pooled processing of bulk samples of multiple
specimens has been suggested to reduce the necessary workload and cost
while still recovering a representative estimate of the prey diversity.
However, it is still unclear if pooling approaches lead to bias in
recovering the prey spectrum and if the results are comparable to data
from individually processed spiders. Here, we test the effect of
metabarcoding pooled spider gut content on the recovered taxonomic
diversity and composition of prey. Using a newly adapted primer pair,
which efficiently enriches COI barcode sequences of diverse arthropod prey
groups while suppressing spider amplification, we test if pooling leads to
reduced taxonomic diversity or skewed estimates of prey composition. Our
results show that pooling and individual processing recover highly
correlated taxonomic diversity and composition of prey. The only exception
are very rare prey items which were less well recovered by pooling. Our
results support pooling as a cost effective and time efficient approach to
recover the diet of generalist predators for population-level studies of
spider trophic interactions.

肠道内容物元条形码（gut content metabarcoding）技术为蜘蛛——这类最具优势的陆生节肢动物捕食者——的食物网生态学研究提供了重要见解。对于蜘蛛这类小型无脊椎动物而言，肠道内容分析通常通过提取单个捕食者的全身体DNA提取物来完成，随后对其中的猎物序列进行选择性富集并测序。
鉴于多数蜘蛛物种均为广食性捕食者，若要详尽获取某一蜘蛛物种的猎物谱全貌，需要对大量单个蜘蛛标本进行分析，这一过程既耗时又成本高昂。
有研究提出采用混合处理多个标本的批量样本的方式，以减少必要的工作量与成本，同时仍能获得具有代表性的猎物多样性评估结果。然而目前仍不明确，混合处理方法是否会导致猎物谱恢复出现偏差，以及其结果是否可与单个处理蜘蛛得到的数据相媲美。
本研究旨在检验元条形码技术对混合蜘蛛肠道内容物处理后，所恢复的猎物分类多样性与组成的影响。我们采用一套新适配的引物对，该引物可高效富集多种节肢动物猎物类群的COI条形码序列，同时抑制蜘蛛自身的扩增，以此检验混合处理是否会降低分类多样性，或是导致猎物组成评估出现偏差。
研究结果显示，混合处理与单个处理所恢复的猎物分类多样性与组成具有高度相关性，仅存在一个例外：极少数稀有猎物类群在混合处理中的恢复效果较差。
本研究结果支持采用混合处理方法，将其作为一种兼具成本效益与时间效率的手段，用于开展蜘蛛营养相互作用的种群水平研究，以获取广食性捕食者的食性信息。