Detecting and removing sample contamination in phylogenomic data: An example and its implications for Cicadidae phylogeny (Insecta: Hemiptera)

Contamination of a genetic sample with DNA from one or more non-target species is a continuing concern of molecular phylogenetic studies, both Sanger sequencing studies and Next-Generation Sequencing (NGS) studies. We developed an automated pipeline for identifying and excluding likely cross-contaminated loci based on detection of bimodal distributions of patristic distances across gene trees. When the contamination occurs between samples within a dataset, comparisons between a contaminated sample and its contaminant taxon will yield bimodal distributions with one peak close to zero patristic distance. Here we present an automated pipeline for identifying and excluding likely cross-contaminated loci based on detection of these bimodal distributions of patristic distances between taxa across gene trees. This new method does not rely on a priori knowledge of taxon relatedness nor does it determine the process(es) that caused the contamination. Exclusion of putatively contaminated loci fro...