Exon probe sets and bioinformatics pipelines for all levels of fish phylogenomics

Abstract

Exon markers have a long history of use in phylogenetics of ray-finned fishes, the most diverse clade of vertebrates with more than 35,000 species. As the number of published genomes increases, it has become easier to test exons and other genetic markers for signals of ancient duplication events and filter out paralogs that can mislead phylogenetic analysis. We present seven new probe sets for current target-capture phylogenomic protocols that capture 1,104 exons explicitly filtered for paralogs using gene trees. These seven probe sets span the diversity of teleost fishes, including four sets that target five hyper-diverse percomorph clades which together comprise ca. 17,000 species (Carangaria, Ovalentaria, Eupercaria, and Syngnatharia + Pelagiaria combined). We additionally included probes to capture exon markers that have been commonly used in fish phylogenetics, despite some being flagged for paralogs, to facilitate integration of old and new molecular phylogenetic matrices. We tested these probes and merged new exon-capture sequence data into an existing data matrix of 1,105 exons and 300 ray-finned fish species. We provide an optimized bioinformatics pipeline to assemble exon capture data from raw reads to alignments for downstream analysis. We show that loci with known paralogs are at risk of assembling duplicated sequences with target-capture, but we also assembled many useful orthologous sequences. These probe sets are a valuable resource for advancing fish phylogenomics because they can be easily extracted from increasingly available whole genome and transcriptome datasets, and also may be integrated with existing PCR-based exon and mitochondrial datasets.