Data from: High-throughput identification of informative nuclear loci for shallow-scale phylogenetics and phylogeography
Lemmon, Alan R.; Lemmon, Emily Moriarty (2012), Data from: High-throughput identification of informative nuclear loci for shallow-scale phylogenetics and phylogeography, Dryad, Dataset, https://doi.org/10.5061/dryad.vh151q1c
One of the major challenges for researchers studying phylogeography and shallow-scale phylogenetics is the identification of highly-variable and informative nuclear loci for the question of interest. Previous approaches to marker generation have generally required extensive testing of loci of unknown utility from other systems or development of markers from the nearest model organism with genomic resources. Here, we present a fast and economical approach to generating thousands of variable, single-copy nuclear loci for any system using next-generation sequencing. We performed Illumina paired-end sequencing of three reduced-representation libraries (RRLs) in chorus frogs (Pseudacris) to identify orthologous, single-copy loci across libraries and to estimate sequence divergence at multiple taxonomic levels. We also conducted PCR testing of these loci across the genus Pseudacris and outgroups to determine whether loci developed for phylogeography can be extended to deeper phylogenetic levels. Prior to sequencing, we conducted in silico digestion of the most closely-related reference genome (Xenopus tropicalis) to generate expectations for the number of loci and degree of coverage for a particular experimental design. Using the RRL approach, we: (1) identified >100,000 single-copy nuclear loci, 6,339 of which were shared across individuals within species and 904 of which were shared between species, (2) estimated average nuclear sequence divergence at 0.1% between alleles within an individual, 1.1% between conspecific individuals, and 1.8% between species, and (3) determined from PCR testing that 53% of the loci successfully amplify within-species and also many amplify to the genus-level and beyond (16%). Our study effectively identified nuclear loci present in the genome that have levels of sequence divergence on par with mitochondrial markers commonly used in phylogeography. Specifically, we estimated that ~7% of loci in the chorus frog genome are >3% divergent within species; this translates to ~50,000 single-copy loci in the genome with >3% divergence. Moreover, successful amplification of many loci at deeper phylogenetic levels indicates that the RRL approach represents an efficient method for rapid generation of informative markers for both phylogenetics and phylogeography. We conclude by making recommendations for minimizing the cost and maximizing the efficiency of marker development for future studies in this field.