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Genome-scale target capture of mitochondrial and nuclear environmental DNA from water samples

Citation

Jensen, Mads Reinholdt; Thomsen, Philip Francis (2020), Genome-scale target capture of mitochondrial and nuclear environmental DNA from water samples, Dryad, Dataset, https://doi.org/10.5061/dryad.4mw6m9086

Abstract

Environmental DNA (eDNA) provides a promising supplement to traditional sampling methods for population genetic inferences, but current studies have almost entirely focused on short mitochondrial markers. Here, we develop one mitochondrial and one nuclear set of target capture probes for the whale shark (Rhincodon typus) and test them on seawater samples collected in Qatar to investigate the potential of target capture for eDNA-based population studies. The mitochondrial target capture successfully retrieved ~235x (90x-352x per base position) coverage of the whale shark mitogenome. Using a minor allele frequency of 5%, we find 29 variable sites throughout the mitogenome, indicative of at least five contributing individuals. We also retrieved numerous mitochondrial reads from an abundant non-target species mackerel tuna (Euthynnus affinis), showing a clear relation between sequence similarity to the capture probes and the number of captured reads. The nuclear target capture probes retrieved only few reads and polymorphic variants from the whale shark, but we successfully obtained millions of reads and thousands of polymorphic variants with different allele frequencies from E. affinis. We demonstrate that target capture of complete mitochondrial genomes and thousands of nuclear loci is possible from aquatic eDNA samples. Our results highlight that careful probe design, taking into account the range of divergence between target and non-target sequences as well as presence of non-target species at the sampling site, is crucial to consider. Environmental DNA sampling coupled with target capture approaches provide an efficient means with which to retrieve population genomic data from aggregating and spawning aquatic species.

Methods

This data is the raw sequencing output for a mitochondrial capture and a nuclear capture using custom-made myBaits target capture. Both captures are based on a single sample (two one-liter eDNA samples combined after extraction) collected in Qatari waters in the middle of a whale shark aggregation, in an area with an expected high abundance of Euthynnus affinis. There is thus no need for demultiplexing. 

The sequencing was performed on a MiSeq with 301 bp PE sequencing. 

Usage Notes

The mitochondrial target capture data consists of two zipped fastq-files (paired-end sequencing):
"MKRJ_S3_L001_R1_001.fastq.gz" and "MKRJ_S3_L001_R2_001.fastq.gz"


The nuclear target capture data consists of two zipped fastq-files (paired-end sequencing):
"M6_S1_L001_R1_001.fastq.gz" and "M6_S1_L001_R2_001.fastq.gz"