Gradients in richness and turnover of a forest passerine’s diet prior to breeding: a mixed model approach applied to faecal metabarcoding data

Little is known about the dietary richness and variation of generalist insectivorous species, including birds, due primarily to difficulties in prey identification. Using faecal metabarcoding we provide the most comprehensive analysis of a passerine’s diet to date, identifying the relative magnitudes of biogeographic, habitat and temporal trends in the richness and turnover in diet of Cyanistes caeruleus (blue tit) along a 39-site, 2° latitudinal transect in Scotland. Faecal samples were collected during 2014-15 from adult birds roosting in nestboxes prior to nest building. DNA was extracted from 793 samples and we amplified COI and 16S minibarcodes. We identified 432 molecular operational taxonomic units (MOTUs) that correspond to putative dietary items. Most dietary items were rare, with Lepidoptera being the most abundant and taxon-rich prey order. We present a novel statistical approach for estimation of gradients and inter-sample variation in taxonomic richness and turnover using a...

由于猎物鉴定难度较大，学界对包括鸟类在内的广食性食虫物种的饮食丰富度与变异程度所知甚少。本研究借助粪便宏条形码（faecal metabarcoding）技术，完成了迄今为止针对雀形目鸟类（passerine）饮食最为全面的分析，明确了苏格兰境内沿39个调查点位、跨度2°纬度的样带上，青山雀（Cyanistes caeruleus, blue tit）饮食丰富度与更替模式在生物地理、生境及时间维度上的相对影响强度。
研究于2014至2015年间，在筑巢前期收集了栖息于巢箱内的成鸟粪便样本。我们从793份样本中提取DNA，并扩增了COI与16S迷你条形码（minibarcodes）。最终共鉴定出432个对应推定饮食组分的分子操作分类单元（molecular operational taxonomic units, MOTUs）。绝大多数饮食组分较为稀有，鳞翅目（Lepidoptera）为丰度最高、类群最丰富的猎物类群。本研究提出了一种全新的统计学方法，用于估算分类群丰富度与更替模式的梯度变化及样本间变异，该方法基于……